Increased gene dosage of RFWD2 causes autistic-like behaviors and aberrant synaptic formation and function in mice.

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by impaired social interactions, communication deficits and repetitive behaviors. A study of autistic human subjects has identified RFWD2 as a susceptibility gene for autism, and autistic patients have 3 copies of the RFWD2 gene. The role of RFWD2 as an E3 ligase in neuronal functions, and its contribution to the pathophysiology of ASD, remain unknown. We generated RFWD2 knockin mice to model the human autistic condition of high gene dosage of RFWD2. We found that heterozygous knockin (Rfwd2+/-) male mice exhibited the core symptoms of autism. Rfwd2+/- male mice showed deficits in social interaction and communication, increased repetitive and anxiety-like behavior, and spatial memory deficits, whereas Rfwd2+/- female mice showed subtle deficits in social communication and spatial memory but were normal in anxiety-like, repetitive, and social behaviors. These autistic-like behaviors in males were accompanied by a reduction in dendritic spine density and abnormal synaptic function on layer II/III pyramidal neurons in the prelimbic area of the medial prefrontal cortex (mPFC), as well as decreased expression of synaptic proteins. Impaired social behaviors in Rfwd2+/- male mice were rescued by the expression of ETV5, one of the major substrates of RFWD2, in the mPFC. These findings indicate an important role of RFWD2 in the pathogenesis of autism.

Klotho Regulated by Estrogen Plays a Key Role in Sex Differences in Stress Resilience in Rats.

Klotho (KL) is a glycosyl hydrolase and aging-suppressor gene. Stress is a risk factor for depression and anxiety, which are highly comorbid with each other. The aim of this study is to determine whether KL is regulated by estrogen and plays an important role in sex differences in stress resilience. Our results showed that KL is regulated by estrogen in rat hippocampal neurons in vivo and in vitro and is essential for the estrogen-mediated increase in the number of presynaptic vesicular glutamate transporter 1 (Vglut1)-positive clusters on the dendrites of hippocampal neurons. The role of KL in sex differences in stress response was examined in rats using 3-week chronic unpredictable mild stress (CUMS). CUMS produced a deficit in spatial learning and memory, anhedonic-like behaviors, and anxiety-like behaviors in male but not female rats, which was accompanied by a reduction in KL protein levels in the hippocampus of male but not female rats. This demonstrated the resilience of female rats to CUMS. Interestingly, the knockdown of KL protein levels in the rat hippocampus of both sexes caused a decrease in stress resilience in both sexes, especially in female rats. These results suggest that the regulation of KL by estrogen plays an important role in estrogen-mediated synapse formation and that KL plays a critical role in the sex differences in cognitive deficit, anhedonic-like behaviors, and anxiety-like behaviors induced by chronic stress in rats, highlighting an important role of KL in sex differences in stress resilience.

Endogenous hippocampal estrogen is involved in stress-induced depression-like behaviors and spine plasticity in male rats.

The estrogen (17ß-estradiol, E2) level in the hippocampus is higher and more stable in male rats than female rats. Both stress and estrogen affect spine plasticity, and many studies have demonstrated that peripheral estrogen treatment can prevent stress-induced spine loss in both males and females. Some in vitro studies have indicated that neural estrogen (nE2) participates in the modulation of spine plasticity in cultured neurons. However, whether nE2 regulates spine density in vivo in males is not clear, and the specific role of nE2 in stress-induced depression-like behaviors of male rats remains unknown. We delivered letrozole (a selective aromatase inhibitor that blocks the conversion of testosterone to estradiol) and estrogen into the hippocampus of rats and found that letrozole treatment induced the same depression-like behaviors in control rats as observed in chronic unpredictable mild stress (CUMS) rats. Estrogen treatment reversed/or alleviated depression-like behaviors induced by CUMS or letrozole infusion and elevated Kalirin-7 expression in hippocampus. Estrogen treatment also rescued letrozole-induced spine loss. Expression of GluN1 and PSD-95 also changed with Kalirin-7 and spine density. All these proteins were decreased in CUMS rats and letrozole infusion rats but increased in rats treated with estrogen. In conclusion, nE2 in the hippocampus plays an important role in CUMS-induced depression-like behaviors in male rats and Kalirin-7 is involved in this process. GluN1 and PSD-95 possibly mediate the regulation of Kalirin-7 by nE2, which ultimately leads to changes in spine density and depression-like behaviors.

[Effects of irrigation at flowering stage on soil nutrient and root distribution in wheat field]. / å°éº¦å¼€èŠ±æœŸçŒæ°´å¯¹åœŸå£¤å »åˆ†åŠæ ¹ç³»åˆ†å¸ƒçš„å½±å“.

To provide theoretical support the full use of water and fertilizer resources for wheat, we explored the effects of irrigation on wheat yield, plant and soil nutrient distribution during flowering period and its relationship with root characteristics. We set up two treatments by using the 2 m deep soil column cultivation method with irrigation during flowering (T1) and no irrigation during flowering (T2), with the drought-resistant and high-yield cultivar Luomai 28 (LM28) and the high photosynthetic efficiency cultivar Bainong 207 (BN207) as materials. We measured contents of nitrogen, phosphorus and potassium in plants and soils, as well as the characteristics of soil roots. The results showed that ammonium, available phosphorus, and available potassium were mainly distributed in 0-80 cm soil layer, and that nitrate was mainly distributed in soil layer below 80 cm during wheat harvest. Irrigation at anthesis stage promoted wheat to absorb ammonium, available phosphorus and available potassium from the upper layer of soil and nitrate nitrogen from the lower layer but did not aggravate the deep leaching of nitrate. The root of wheat mainly concentrated in 0-60 cm soil layer and decreased with increasing soil depth. Dry matter accumulation, total nitrogen and total phosphorus were mainly distributed in wheat grains at maturity, while total potassium was mainly distributed in stems. Irrigation at anthesis stage significantly increased the 100-grain weight of wheat, and consequently the yield. Root morphology was negatively correlated with soil nitrate in 0-40 cm soil layer, positively correlated with soil ammonium in 80-100 cm soil layer and soil available phosphorus in 0-100 cm soil layer. Irrigation at anthesis stage promoted the full absorption of soil nutrients by roots at late filling stage, delayed the senescence of flag leaves after flowering, prolonged the functional period of transporting nutrients from vegetative organs to reproductive organs, leading nutrients in vegetative organs more fully transported to grains, increasing grain weight and yield.

Osthole Ameliorates Estrogen Deficiency-Induced Cognitive Impairment in Female Mice.

Loss of endogenous estrogen and dysregulation of the estrogen receptor signaling pathways are associated with an increase in risk for cognitive deficit and depression in women after menopause. Estrogen therapy for menopause increases the risk of breast and ovarian cancers, and stroke. Therefore, it is critical to find an alternate treatment for menopausal women. Osthole (OST), a coumarin, has been reported to have neuroprotective effects. This study examined whether OST improves ovariectomy (OVX)-induced cognitive impairment, and alleviates anxiety- and depression-like behaviors induced by OVX in mice. Adult female C57BL/6J mice were ovariectomized and then treated with OST at a dose of 30 mg/kg for 14 days. At the end of the treatment period, behavioral tests were used to evaluate spatial learning and memory, recognition memory, anxiety- and depression-like behaviors. A cohort of the mice were sacrificed after 14 days of OST treatment and their hippocampi were collected for measurement of the proteins of interest using western blot. OVX-induced alteration in the levels of proteins was accompanied by cognitive deficit, anxiety- and depression-like behaviors. OST treatment improved cognitive deficit, alleviated anxiety- and depression-like behaviors induced by OVX, and reversed OVX-induced alterations in the levels of synaptic proteins and ERα, BDNF, TrKB, p-CREB, p-Akt and Rac1 in the hippocampus. Therefore, reversal of OVX-induced decrease in the levels of hippocampal proteins by OST might contribute to the effects of OST on improving cognitive deficit and alleviating anxiety- and depression-like behaviors induced by OVX.

[Effects of row spacing and sowing rate on vertical distribution of photosynthetically active radiation, biomass, and grain yield in winter wheat canopy.] / è¡Œè·å’Œæ’­ç§é‡å¯¹å†¬å°éº¦å† å±‚å ‰åˆæœ‰æ•ˆè¾å°„åž‚ç›´åˆ†å¸ƒã€ç”Ÿç‰©é‡å’Œç±½ç²’äº§é‡çš„å½±å“.

To clarify the effects of row spacing and sowing rate on the vertical distribution of canopy PAR, biomass, and grain yield in winter wheat, a field experiment was conducted without increa-sing water and fertilizer input. There were two row spacing modes, R1 (equal spacing, 20 cm+20 cm) and R2(wide and narrow row spacing, 12 cm+12 cm+12 cm+24 cm), and three sowing rates, D1 (low, 120 kg·hm-2), D2 (medium, 157.5 kg·hm-2), D3 (high, 195 kg·hm-2). The canopy photosynthetically active radiation (PAR) interception and utilization rate in different heights, population photosynthetic capacity, biomass, and grain yield were measured during the main growth stages of winter wheat. The results showed that both total PAR interception and upper layer PAR interception of winter wheat canopy under R1 treatment were significantly higher than those in R2 treatment, but those of the middle layer and lower layer were higher in R2 than in R1, and with significant difference in the middle layer. From flowering to maturity, the photosynthetic potential (LAD), population photosynthetic rate (CAP), PAR conversion rate, and utilization rate in R2 were all significantly higher than those in R1 under the same sowing rate, with the highest value under R2D2 treatment. With the increasing sowing rate, the population biomass (BA) and leaf biomass (BL) at different layers increased, but the individual biomass (BP) showed an opposite trend. Under the same sowing rate, BA, BL and BP in R2 were higher than that in R1 after the flowering stage. Among them, BA and BP had significant difference in row spacing treatments at the maturity stage, with significant difference between the two row spacing treatments being observed in BL of the middle and lower layers under D2 and D3 sowing rates. The spike number, grain number per spike, 1000-kernel weight, and grain yield of winter wheat among different treatments were the highest in R2D3, R2D1, R2D1, and R2D2, respectively. The 1000-kernel weight, grain number per spike and grain yield in R2 treatment were significantly higher than R1. In summary, the PAR interception in the middle and lower layers of winter wheat canopy was improved by changing row spacing, with positive consequence on the photosynthetic capacity of individual plant and population, PAR utilization and transformation efficiency, which finally increased biomass and grain yield. Therefore, optimizing the field structure and shaping the ideal population photosynthetic structure should pay more attention during the high-yield cultivation of winter wheat. Making full use of light resources per unit land area and excavating the photosynthetic production potential of crops were also critical to achieve high yield and efficiency. In this experiment, the population photosynthetic capacity, photosynthetic effective radiation utilization rate, and yield were the highest under the treatment of R2D2.

Cell-type specific knockout of peptidylglycine α-amidating monooxygenase reveals specific behavioral roles in excitatory forebrain neurons and cardiomyocytes.

Neuropeptides and peptide hormones play a crucial role in integrating the many factors that affect physiologic and cognitive processes. The potency of many of these peptides requires an amidated amino acid at the C-terminus; a single enzyme, peptidylglycine α-amidating monooxygenase (PAM), catalyzes this modification. Anxiety-like behavior is known to be altered in mice with a single functional Pam allele (Pam+/- ) and in mice unable to express Pam in excitatory forebrain neurons (PamEmx1-cKO/cKO ) or in cardiomyocytes (PamMyh6-cKO/cKO ). Examination of PAM-positive and glutamic acid decarboxylase 67 (GAD)-positive cells in the amygdala of PamEmx1-cKO/cKO mice demonstrated the absence of PAM in pyramidal neurons and its continued presence in GAD-positive interneurons, suggestive of altered excitatory/inhibitory balance. Additional behavioral tests were used to search for functional alterations in these cell-type specific knockout mice. PamEmx1-cKO/cKO mice exhibited a less focused search pattern for the Barnes Maze escape hole than control or PamMyh6-cKO/cKO mice. While wildtype mice favor interacting with novel objects as opposed to familiar objects, both PamEmx1-cKO/cKO and PamMyh6-cKO/cKO mice exhibited significantly less interest in the novel object. Since PAM levels in the central nervous system of PamMyh6-cKO/cKO mice are unaltered, the behavioral effect observed in these mice may reflect their inability to produce atrial granules and the resulting reduction in serum levels of atrial natriuretic peptide. In the sociability test, male mice of all three genotypes spent more time with same-sex stranger mice; while control females showed no preference for stranger mice, female PamEmx1-cKO/cKO mice showed preference for same-sex stranger mice in all trials.

7, 8-Dihydroxy-4-methylcoumarin reverses depression model-induced depression-like behaviors and alteration of dendritic spines in the mood circuits.

Major depressive disorder (MDD) is a common mental disorder characterized by a persistent feeling of sadness, slow thought, impaired focus and loss of interest but the underlying mechanisms are largely unknown. Dendritic spines play an important role in the formation and maintenance of emotional circuits in the brain. Abnormalities in this process can lead to psychiatric diseases. 7,8-Dihydroxy-4-methylcoumarin (Dhmc), a precursor in the synthesis of derivatives of 4-methyl coumarin, plays an important role in protecting the nervous system from developing diseases and its most distinctive feature is safety. The aim of this study was to investigate whether Dhmc alleviates chronic unpredictable mild stress (CUMS)-induced depression-like behaviors and reverses CUMS-induced alterations in dendritic spines of principal neurons in brain areas of the emotional circuits including the hippocampus, medial prefrontal cortex (mPFC), nucleus accumbens (NAc) and basolateral amygdala (BLA) in male rats. Our results showed that CUMS-induced depression-like behaviors were accompanied by a decrease in spine density in pyramidal neurons of both the hippocampal CA3 area and the mPFC, and an increase in spine density in both the neurons of BLA and the medium spiny neurons (MSNs) of the NAc, as well as a decrease in the levels of the AMPA receptor subunit GluA1 and Kalirin-7 in the hippocampus compared with the control group. Intraperitoneal injection (i.p.) of Dhmc to the CUMS-exposed rats ameliorated CUMS-induced depression-like behaviors and reversed CUMS-mediated alterations in spine density and the levels of both GluA1 and Kalirin-7. Our results show an important role of Dhmc in reversing CUMS-induced depression-like behaviors and CUMS-mediated alterations in spine density.

Sex difference in depression: Which animal models mimic it.

Depression affects both women and men, but women are 2 times more susceptible to the incidence of depression. Although a number of studies report sex differences in stress responses, it remains unclear which animal models of depression can better mimic the sex difference in human depression. The majority of stress models used male rodents whereas fewer studies included females. The aims of this study were to determine which rat stress models mimic the sex difference in depression and to identify sex-specific risk factors for depression model-induced depression-like behaviors. Here, we compared subchronic variable stress (SCVS) and chronic unpredictable mild stress (CUMS) models to evaluate the susceptibility versus resilient phenotypes in male and female rats. SCVS induced depression-like behaviors in female rats only. The CUMS paradigm was more likely to induce depression-like behaviors in male rats. Furthermore, to explore the underlying mechanisms, we used quantitative reverse transcriptase polymerase chain reaction to examine and compare the messenger RNA (mRNA) levels of various transcripts previously shown to be involved in psychiatric disorders in RNA-sequencing/microarray studies including serotonin receptor-7, early growth response-2, histone deacetylase-2, roundabout guidance receptor-2 (Robo2), serum/glucocorticoid regulated kinase-2, orthodenticle homeobox-2, parathyroid hormone-2 receptor, and neuronal PAS domain protein-4 in the hippocampus after exposure of rats to SCVS and CUMS. Our results showed that SCVS significantly altered the mRNA levels of neuronal PAS domain protein-4, orthodenticle homeobox-2, Robo2, parathyroid hormone-2 receptor, and serum/glucocorticoid regulated kinase-2 in the female hippocampus only, and histone deacetylase-2 in only the male hippocampus. CUMS significantly changed the mRNA levels of one transcript (Robo2) in the female hippocampus only when compared with SCVS. Overall, this study shows that SCVS can be used to study sex differences in depression-like behaviors in rats. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

Impact of subchronic variable stress on ovariectomy and dendritic spine density in prefrontal cortex in mice.

Major depressive disorder affects both women and men but females are two times more susceptible to the incidence of depression. The majority of stress models used male rodents, whereas fewer studies included females. Volumetric reductions have been reported in brain areas critical for the stress response, such as prefrontal cortex, and remodeling of dendritic spines has been proposed as an underlying factor. The aim of this study was to determine the effects of subchronic variable stress (SCVS) in males, sham, and specifically in ovariectomized (OVX) female mice. Here, we used 6 days SCVS model to induce depressive-like behavior, and only the OVX female mice showed the depressive-like behavior, while males showed resilient type behavior. Only OVX female mice showed significant increase in dendritic spine density in SCVS paradigm. Overall, this study suggests that (1) the effects SCVS produced on the behavior of males and OVX females and (2) SCVS may induce rapid and sustained changes of PL neurons, which highlights the importance of gonadal hormones in studying depression.

Involvement of D2 receptor in the NAc in chronic unpredictable stress-induced depression-like behaviors.

D2 receptors (D2Rs) located in both pre- and postsynaptic membranes of medium spiny neurons (MSNs) in the nucleus accumbens (NAc) are involved in the stress response and associated behaviors. The role of D2Rs in chronic unpredictable stress (CUS)-induced depression-like behaviors is not clear. Quinpirole (a D2R agonist) and eticlopride (a D2R antagonist) were stereotactically delivered into the NAc before Sprague Dawley rats underwent CUS. CUS-induced depression-like behaviors were accompanied by a significant decrease in both the dopamine (DA) level and D2R expression in the NAc. Eticlopride reversed CUS-induced depression-like behavior and rescued the DA levels in the NAc, and microinjection of DA into the NAc of CUS individuals had the same effect as eticlopride. By contrast, delivery of quinpirole into the NAc of control animals induced depression-like behaviors accompanied by a decrease in the DA level in the NAc. These results show that DA plays a key role in CUS-induced depression-like behaviors and the D2R exerts a presynaptic negative feedback on DA levels during CUS. Microinjection of quinpirole into the NAc also decreased the level of the kalirin-7 protein in the NAc of both control and stressed animals, while eticlopride increased its level in the NAc of rats. In agreement with these results, intraperitoneal injection of eticlopride in mice also caused an increase in both the kalirin-7 protein level in the NAc and spine density in MSNs, while quinpirole reduced them. These results suggest that regulation of kalirin-7 through D2R in the NAc is a general pathway in rats and mice, and is involved in CUS-induced depression-like behaviors. Kalirin-7 may be directly regulated through the D2R postsynaptic pathway or indirectly through the presynaptic pathway in the NAc. The interaction between D2R and kalirin-7 needs to be investigated further.

Estradiol Alters Hippocampal Gene Expression during the Estrous Cycle.

Estrogen (E2) modulates a wide range of neural functions such as spine formation, synaptic plasticity, and neurotransmission in the hippocampus. Dendritic spines and synapse numbers in hippocampal neurons of female rats cyclically fluctuate across the estrous cycle, but the key genes responsible for these fluctuations are still unknown. In order to address this question, we explore the hippocampal transcriptome via RNA-sequencing (RNA-seq) at the proestrus (PE) and estrus (ES) stages in female rats. At standard fold-change selection criteria, 37 differentially expressed genes (DEGs) were found in PE vs. ES groups (FDR adjusted p-value (q)<0.05). The transcriptional changes identified by RNA-seq were confirmed by quantitative real-time PCR. To gain insight into the function of the DEGs, the E2-regulated genes were annotated by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes database (KEGG). Based on GO and KEGG pathways, the identified DEGs of PE vs. ES stages are involved in extracellular matrix formation, regulation of actin cytoskeleton, oxidative stress, neuroprotection, immune system, oligodendrocyte maturation and myelination, signal transduction pathways, growth factor signaling, retinoid signaling, aging, cellular process, metabolism and transport. The profiles of the gene expression in the hippocampus identified at the PE vs. ES stages were compared with the gene expression profiles in ovariectomized (OVX) rats receiving E2 replacement via RNA-seq and qPCR. The profiles of gene expression between the OVX+E2 and the estrous cycle were different and the possible causes were discussed.

Identifying roles for peptidergic signaling in mice.

Despite accumulating evidence demonstrating the essential roles played by neuropeptides, it has proven challenging to use this information to develop therapeutic strategies. Peptidergic signaling can involve juxtacrine, paracrine, endocrine, and neuronal signaling, making it difficult to define physiologically important pathways. One of the final steps in the biosynthesis of many neuropeptides requires a single enzyme, peptidylglycine α-amidating monooxygenase (PAM), and lack of amidation renders most of these peptides biologically inert. PAM, an ancient integral membrane enzyme that traverses the biosynthetic and endocytic pathways, also affects cytoskeletal organization and gene expression. While mice, zebrafish, and flies lacking Pam (PamKO/KO ) are not viable, we reasoned that cell type-specific elimination of Pam expression would generate mice that could be screened for physiologically important and tissue-specific deficits. Conditional PamcKO/cKO mice, with loxP sites flanking the 2 exons deleted in the global PamKO/KO mouse, were indistinguishable from wild-type mice. Eliminating Pam expression in excitatory forebrain neurons reduced anxiety-like behavior, increased locomotor responsiveness to cocaine, and improved thermoregulation in the cold. A number of amidated peptides play essential roles in each of these behaviors. Although atrial natriuretic peptide (ANP) is not amidated, Pam expression in the atrium exceeds levels in any other tissue. Eliminating Pam expression in cardiomyocytes increased anxiety-like behavior and improved thermoregulation. Atrial and serum levels of ANP fell sharply in PAM myosin heavy chain 6 conditional knockout mice, and RNA sequencing analysis identified changes in gene expression in pathways related to cardiac function. Use of this screening platform should facilitate the development of therapeutic approaches targeted to peptidergic pathways.

Increased anxiety and decreased sociability induced by paternal deprivation involve the PVN-PrL OTergic pathway.

Early adverse experiences often have devastating consequences. However, whether preweaning paternal deprivation (PD) affects emotional and social behaviors and their underlying neural mechanisms remain unexplored. Using monogamous mandarin voles, we found that PD increased anxiety-like behavior and attenuated social preference in adulthood. PD also decreased the number of oxytocin (OT)-positive neurons projecting from the paraventricular nucleus (PVN) and reduced the levels of the medial prefrontal cortex OT receptor protein in females and of the OT receptor and V1a receptor proteins in males. Intra-prelimbic cortical OT injections reversed the PD-induced changes in anxiety-like behavior and social preferences. Optogenetic activation of the prelimbic cortex OT terminals from PVN OT neurons reversed the PD-induced changes in emotion and social preference behaviors, whereas optogenetic inhibition was anxiogenic and impaired social preference in naive voles. These findings demonstrate that PD increases anxiety-like behavior and attenuates social preferences through the involvement of PVN OT neuron projections to the prelimbic cortex.

Treadmill Exercise Reverses Depression Model-Induced Alteration of Dendritic Spines in the Brain Areas of Mood Circuit.

Depression is one of the most prevalent psychiatric disorders. Exercise has been shown to be effective in the amelioration of depression, but the underlying mechanism remains largely unknown. Alterations in the density and morphology of dendritic spines are associated with psychiatric diseases. Chronic unpredictable mild stress (CUMS) is an established animal model of depression. The aim of this study was to determine whether treadmill exercise reverses CUMS-induced both depression-like behaviors and alterations in spine density and morphology of the principal neurons in the brain areas of the mood circuits including the hippocampus, medial prefrontal cortex (mPFC), nucleus accumbens (NAc) and basolateral amygdala (BLA). Male rats were randomly divided into four groups: control, CUMS, exercise, and CUMS+exercise. CUMS-induced depression-like behaviors were evaluated by the sucrose preference test (SPT). Golgi staining was used to visualize dendritic spines. Our results showed that CUMS-induced depression-like behaviors characterized by a decrease in sucrose consumption were accompanied by a decrease in spine density and a change in spine morphology in the pyramidal neurons of both the hippocampal CA3 area and the mPFC, and an increase in spine density and an alteration in spine shape in both the NAc medium spiny neurons (MSNs) and the BLA neurons; exercise reversed both CUMS-induced depression-like behaviors and alterations in dendritic spines. This study provides important information for understanding the mechanism through which exercise ameliorates CUMS-induced depression-like behaviors.

Sequential formation of different layers of dystrophic neurites in Alzheimer's brains.

Alzheimer's disease (AD) is characterized by the presence of neuritic plaques in which dystrophic neurites (DNs) are typical constituents. We recently showed that DNs labeled by antibodies to the tubular endoplasmic reticulum (ER) protein reticulon-3 (RTN3) are enriched with clustered tubular ER. However, multi-vesicle bodies are also found in DNs, suggesting that different populations of DNs exist in brains of AD patients. To understand how different DNs evolve to surround core amyloid plaques, we monitored the growth of DNs in AD mouse brains (5xFAD and APP/PS1ΔE9 mice) by multiple approaches, including two-dimensional and three-dimensional (3D) electron microscopy (EM). We discovered that a pre-autophagosome protein ATG9A was enriched in DNs when a plaque was just beginning to develop. ATG9A-positive DNs were often closer to the core amyloid plaque, whereas RTN3 immunoreactive DNs were mostly located in the outer layers of ATG9A-positive DNs. Proteins such as RAB7 and LC3 appeared in DNs at later stages during plaque growth, likely accumulated as a part of large autophagy vesicles, and were distributed relatively furthest from the core amyloid plaque. Reconstructing the 3D structure of different morphologies of DNs revealed that DNs in AD mouse brains were constituted in three layers that are distinct by enriching different types of vesicles, as validated by immune-EM methods. Collectively, our results provide the first evidence that DNs evolve from dysfunctions of pre-autophagosomes, tubular ER, mature autophagosomes, and the ubiquitin proteasome system during plaque growth.

Role of Cdk5 in Kalirin7-Mediated Formation of Dendritic Spines.

A majority of excitatory synapses in the brain are localized on the dendritic spines. Alterations of spine density and morphology are associated with many neurological diseases. Understanding the molecular mechanisms underlying spine formation is important for understanding these diseases. Kalirin7 (Kal-7) is localized to the postsynaptic side of excitatory synapses in the neurons. Overexpression of Kal-7 causes an increase in spine density whereas knockdown expression of endogenous Kal-7 results in a decrease in spine density in primary cultured cortical neurons. However, the mechanisms underlying Kal-7-mediated spine formation are not entirely clear. Cyclin-dependent kinase 5 (Cdk5) plays a vital role in the formation of spines and synaptic plasticity. Kal-7 is phosphorylated by CDK5 at Thr1590, the unique Cdk5 phosphorylation site in the Kal-7 protein. This study was to explore the role of CDK5-mediated phosphorylation of Kal-7 in spine formation and the underlying mechanisms. Our results showed expression of Kal-7T/D (mimicked phosphorylation), Kal-7T/A mutants (blocked phosphorylation) or wild-type (Wt) Kal-7 caused in a similar increase in spine density, while spine size of Wt Kal-7-expressing cortical neurons was bigger than that in Kal-7 T\A-expressing neurons, but smaller than that in Kal-7T/D-expressing neurons. The fluorescence intensity of NMDA receptor subunit NR2B (GluN2B) staining was stronger along the MAP2 positive dendrites of Kal-7T/D-expressing neurons than that in Kal-7T/A- or Wt Kal-7-expressing neurons. The fluorescence intensity of AMPA receptor subunit GluR1 (GluA1) staining showed the same trend as GluN2B staining. These findings suggest that Cdk5 affects the function of Kal-7 on spine morphology and function via GluN2B and GluA1 receptors during dendritic spine formation.

Modulation of Kalirin-7 expression by hippocampal CA1 5-HT1B receptors in spatial memory consolidation.

Serotonin 5-HT1B receptors (5-HT1BRs) are distributed in hippocampal CA1 and play a pivotal role in cognitive function. Activation of 5-HT1BRs regulates synaptic plasticity at the excitatory synapses in the hippocampus. However, the role and its underlying mechanism of 5-HT1BR activation-mediated glutamatergic synaptic plasticity in spatial memory are not fully understood. In this study, spatial memory of Sprague-Dawley (SD) rats was assessed in a Morris water maze after bilateral dorsal hippocampal CA1 infusion of the 5-HT1BR antagonist GR55562 (25 µg/µL) or agonist CP93129 (25 µg/µL). GR55562 did not affect the spatial memory acquisition but significantly increased the target quadrant preference during the memory consolidation probe performed 14 d after the training session, while CP93129 impaired the memory consolidation process. Moreover, GR55562 significantly increased, while CP93129 significantly decreased, the density of dendritic spines on the distal apical dendrites of CA1 pyramidal neurons. Furthermore, western blot experiments indicated that GR55562 significantly increased, but CP93129 significantly reduced, the expression of Kalirin-7 (Kal-7), PSD95, and GluA2/3 subunits of AMPA receptors. Our results suggest that Kal-7 and Kal-7-mediatedalteration of AMPA receptor subtype expression may play crucial roles in the impact of hippocampal CA1 5-HT1BR activation on spatial memory consolidation.

Role of proBDNF and BDNF in dendritic spine plasticity and depressive-like behaviors induced by an animal model of depression.

Major depressive disorder (MDD) is one of the most common psychiatric disorder, but the underlying mechanisms are largely unknown. Increasing evidence shows that brain-derived neurotrophic factor (BDNF) plays an important role in the structural plasticity induced by depression. Considering the opposite effects of BDNF and its precursor proBDNF on neural plasticity, we hypothesized that the balance of BDNF and proBDNF plays a critical role in chronic unpredicted mild stress (CUMS)-induced depressive-like behaviors and structural plasticity in the rodent hippocampus. The aims of this study were to compare the functions of BDNF and proBDNF in the CUMS-induced depressive-like behaviors, and determine the effects of BDNF and proBDNF on expressions of kalirin-7, postsynaptic density protein 95 (PSD95) and NMDA receptor subunit NR2B in the hippocampus of stressed and naïve control rats, respectively. Our results showed that CUMS induced depressive-like behaviors, caused a decrease in the ratio of BDNF/proBDNF in the hippocampus and resulted in a reduction in spine density in hippocampal CA1 pyramidal neurons; these alterations were accompanied by a decrease in the levels of kalirin-7, PSD95 and NR2B in the hippocampus. Injection of exogenous BDNF into the CA1 area of stressed rats reversed CUMS-induced depressive-like behaviors and prevented CUMS-induced spine loss and decrease in kalirin-7, NR2B and PSD95 levels. In contrast, injection of exogenous proBDNF into the CA1 region of naïve rats caused depressive-like behavior and an accompanying decrease in both spine density and the levels of kalirin-7, NR2B and PSD95. Taken together, our results suggest that the ratio of BDNF to proBDNF in the hippocampus plays a key role in CUMS-induced depressive-like behaviors and alterations of dendritic spines in hippocampal CA1 pyramidal neurons. Kalirin-7 may play an important role during this process.

[Effects of tillage and nitrogen application rate on soil nitrogen transformation and yield in a winter wheat/summer maize multiple cropping system]. / 耕作方式与施氮量对小麦-çŽ‰ç±³å¤ç§ç³»ç»ŸçŽ‰ç±³å­£åœŸå£¤æ°®ç´ è½¬åŒ–åŠäº§é‡çš„å½±å“.

In the winter-wheat and summer-maize multiple cropping system in lime concretion black soil of Huanghuaihai Plain, the effects of three tilling methods (conventional tillage, rotary tillage, subsoiling tillage) in wheat season coupling with three nitrogen treatments (120 kg·hm-2, 225 kg·hm-2, 330 kg·hm-2) before maize sowing on the activities of microorganisms and enzymes re-lated nitrogen transformation, and inorganic nitrogen content in the rhizosphere soil during the main growth stages of maize, as well as the yield were investigated. The results showed that the rotary tillage had the highest ammonification intensity, and the more nitrogen was put in, the higher were the activities of microorganisms and enzymes related to soil nitrogen transformation. The activities of nitrification, denitrification and urease of subsoiling tillage was significantly higher than those of conventional and rotary tillage. Furthermore, in subsoiling tillage treatment, increasing nitrogen fertili-zer could promote soil nitrogen transformation while excessive nitrogen input inhibited soil nitrogen transformation, though the latter had higher yield and soil inorganic nitrogen content. The treatment of subsoiling tillage coupling with 225 kg·hm-2 nitrogen, was best for soil nitrogen transformation while the treatment of subsoiling tillage coupling with 330 kg·hm-2 nitrogen, had the highest corn yield.