New Insight into the Function of Dopamine (DA) during Cd Stress in Duckweed (Lemna turionifera 5511).

Dopamine (DA), a kind of neurotransmitter in animals, has been proven to cause a positive influence on plants during abiotic stress. In the present study, the function of DA on plants under cadmium (Cd) stress was revealed. The yellowing of duckweed leaves under Cd stress could be alleviated by an exogenous DA (10/20/50/100/200 µM) supplement, and 50 µM was the optimal concentration to resist Cd stress by reducing root breakage, restoring photosynthesis and chlorophyll content. In addition, 24 h DA treatment increased Cd content by 1.3 times in duckweed under Cd stress through promoting the influx of Cd2+. Furthermore, the gene expression changes study showed that photosynthesis-related genes were up-regulated by DA addition under Cd stress. Additionally, the mechanisms of DA-induced Cd detoxification and accumulation were also investigated; some critical genes, such as vacuolar iron transporter 1 (VIT1), multidrug resistance-associated protein (MRP) and Rubisco, were significantly up-regulated with DA addition under Cd stress. An increase in intracellular Ca2+ content and a decrease in Ca2+ efflux induced by DA under Cd stress were observed, as well as synchrony with changes in the expression of cyclic nucleotide-gated ion channel 2 (CNGC2), predicting that, in plants, CNGC2 may be an upstream target for DA action and trigger the change of intracellular Ca2+ signal. Our results demonstrate that DA supplementation can improve Cd resistance by enhancing duckweed photosynthesis, changing intracellular Ca2+ signaling, and enhancing Cd detoxification and accumulation. Interestingly, we found that exposure to Cd reduced endogenous DA content, which is the result of a blocked shikimate acid pathway and decreased expression of the tyrosine aminotransferase (TAT) gene. The function of DA in Cd stress offers a new insight into the application and study of DA to Cd phytoremediation in aquatic systems.

Female is Associated with Left Ventricular Diastolic Dysfunction in Patients with Type 2 Diabetes.

Aim: Diabetic cardiomyopathy is a subset of heart disease that is directly associated with diabetes, and left ventricular diastolic dysfunction is the earliest sign. We aimed to investigate the association between sex differences and left ventricular diastolic function in patients with type 2 diabetes. Methods: This was a cross-sectional study included patients with type 2 diabetes who visit the National Metabolic Management Center (MMC) at the First People's Hospital of Yunnan from 2018 to 2021. Patients with hypertension, history of heart disease or ejection fraction <50% were excluded from the study. Logistic regression was used to analyze their associations. Results: A total of 1778 patients were included in the study. The study included 1205 (70%) males and 573 (30%) females. Compared with males, females had higher total cholesterol and LDL cholesterol levels but lower diastolic pressure, body mass index (BMI), visceral fat area, HbA1c, blood urea nitrogen (BUN), serum creatinine and triglyceride. Females had a relatively higher ejection fraction than males (68.17 ± 6.055 vs 67.5 ± 6.096, P < 0.05). More female patients than male patients in the age group of 45-60 years old had left ventricular diastolic dysfunction (female vs male, 54.5% vs 46.9%, P < 0.05). We also found that females were independently associated with left ventricular diastolic dysfunction, after adjusting for important clinical factors. Conclusion: Left ventricular diastolic function might be worse in female patients with type 2 diabetes. Further study is needed to verify the underlying mechanism.

The Antimicrobial Potential and Aquaculture Wastewater Treatment Ability of Penaeidins 3a Transgenic Duckweed.

With the development of aquaculture, wastewater treatment and diseases have been paid more and more attention. The question of how to improve the immunity of aquatic species, as well as treat aquaculture wastewater, has become an urgent problem. In this study, duckweed with a high protein content (37.4%) (Lemna turionifera 5511) has been employed as a feedstock for aquatic wastewater treatment and the production of antimicrobial peptides. Penaeidins 3a (Pen3a), from Litopenaeus vannamei, were expressed under the control of CaMV-35S promoter in duckweed. Bacteriostatic testing using the Pen3a duckweed extract showed its antibacterial activity against Escherichia coli and Staphylococcus aureus. Transcriptome analysis of wild type (WT) duckweed and Pen3a duckweed showed different results, and the protein metabolic process was the most up-regulated by differential expression genes (DEGs). In Pen3a transgenic duckweed, the expression of sphingolipid metabolism and phagocytosis process-related genes have been significantly up-regulated. Quantitative proteomics suggested a remarkable difference in protein enrichment in the metabolic pathway. Pen3a duckweed decreased the bacterial number, and effectively inhibited the growth of Nitrospirae. Additionally, Pen3a duckweed displayed better growth in the lake. The study showed the nutritional and antibacterial value of duckweed as an animal feed ingredient.

Evidence for the role of sound on the growth and signal response in duckweed.

Sound vibration, an external mechanical force, has been proven to modulate plant growth and development like rain, wind, and vibration. However, the role of sound on plants, especially on signal response, has been usually neglected in research. Herein, we investigated the growth state, gene expression, and signal response in duckweed treated with soft music. The protein content in duckweed after music treatment for 7 days was about 1.6 times that in duckweed without music treatment. Additionally, the potential maximum photochemical efficiency of photosystem II (Fv/Fm) ratio in duckweed treated with music was 0.78, which was significantly higher in comparison with the control group (P < .01). Interestingly, music promoted the Glu and Ca signaling response. To further explore the global molecular mechanism, we performed transcriptome analysis and the library preparations were sequenced on an Illumina Hiseq platform. A total of 1296 differentially expressed genes (DEGs) were found for all these investigated genes in duckweed treated with music compared to the control group. Among these, up-regulation of the expression of metabolism-related genes related to glycolysis, cell wall biosynthesis, oxidative phosphorylation, and pentose phosphate pathways were found. Overall, these results provided a molecular basis to music-triggered signal response, transcriptomic, and growth changes in duckweed, which also highlighted the potential of music as an environmentally friendly stimulus to promote improved protein production in duckweed.

Mechanism of calcium signal response to cadmium stress in duckweed.

Cadmium (Cd) causes serious damage to plants. Although calcium (Ca) signal has been found to respond to certain stress, the localization of Ca and molecular mechanisms underlying Ca signal in plants during Cd stress are largely unknown. In this study, Ca2+-sensing fluorescent reporter (GCaMP3) transgenic duckweed showed the Ca2+ signal response in Lemna turionifera 5511 (duckweed) during Cd stress. Subsequently, the subcellular localization of Ca2+ has been studied during Cd stress by transmission electron microscopy, showing the accumulation of Ca2+ in vacuoles. Also, Ca2+ flow during Cd stress has been measured. At the same time, the effects of exogenous glutamic acid (Glu) and γ-aminobutyric (GABA) on duckweed can better clarify the signal operation mechanism of plants to Cd stress. The molecular mechanism of Ca2+ signal responsed during Cd stress showed that Cd treatment promotes the positive response of Ca signaling channels in plant cells, and thus affects the intracellular Ca content. These novel signal studies provided an important Ca2+ signal molecular mechanism during Cd stress.

New insight into the effect of riluzole on cadmium tolerance and accumulation in duckweed (Lemna turionifera).

Cadmium (Cd) damages plant photosynthesis, affects roots and leaves growth, and triggers molecular responses. Riluzole (RIL), which protected neuronal damage via inhibiting excess Glu release in animals, has been found to improve Cd tolerance in duckweed in this study. Firstly, RIL treatment alleviated leaf chlorosis by protecting chlorophyll and decreased root abscission under Cd stress. Secondly, RIL declines Cd accumulation by alleviating excess Glu release during Cd shock. RIL mitigate Glu outburst in duckweed during Cd stress by a decline in Glu in roots. The Cd2+ influx was repressed by RIL addition with Cd shock. Finally, differentially expressed genes (DEGs) of duckweed under Cd stress with RIL have been investigated. 2141 genes were substantially up-regulated and 3282 genes were substantially down-regulated with RIL addition. RIL down-regulates the genes related to the Glu synthesis, and genes related to DNA repair have been up-regulated with RIL treatment under Cd stress. These results provide new insights into the possibility of RIL to reduce Cd accumulation and increase Cd tolerance in duckweed, and lay the foundation for decreasing Cd accumulation in crops.

Drosophila TRPγ is required in neuroendocrine cells for post-ingestive food selection.

The mechanism through which the brain senses the metabolic state, enabling an animal to regulate food consumption, and discriminate between nutritional and non-nutritional foods is a fundamental question. Flies choose the sweeter non-nutritive sugar, L-glucose, over the nutritive D-glucose if they are not starved. However, under starvation conditions, they switch their preference to D-glucose, and this occurs independent of peripheral taste neurons. Here, we found that eliminating the TRPγ channel impairs the ability of starved flies to choose D-glucose. This food selection depends on trpγ expression in neurosecretory cells in the brain that express diuretic hormone 44 (DH44). Loss of trpγ increases feeding, alters the physiology of the crop, which is the fly stomach equivalent, and decreases intracellular sugars and glycogen levels. Moreover, survival of starved trpγ flies is reduced. Expression of trpγ in DH44 neurons reverses these deficits. These results highlight roles for TRPγ in coordinating feeding with the metabolic state through expression in DH44 neuroendocrine cells.

Nitric oxide (NO) involved in Cd tolerance in NHX1 transgenic duckweed during Cd stress.

Anthropogenic activities cause heavy metal pollution, such as cadmium (Cd). Na+/H+ antiporter (NHX1) transgenic duckweed showed Cd tolerance in our previous study, and the signal mechanism needs to be explored. As an important signal molecule, nitric oxide (NO) is involved in a number of functions under abiotic stress response. This study analyzed the levels of endogenous NO in wild-type (WT) duckweed and NHX1 duckweed under Cd treatment. The results showed that after 24 h Cd treatment, the endogenous NO level of WT duckweed decreased, which was significantly lower than that in NHX1 duckweed. Studies have proved that NHX1 influences pH. The level of NO in this study has been investigated at different pH. The NO level was the highest in the duckweed cultured with pH 5.3. Nitrate reductase gene expression was down-regulated and NO synthesis was decreased under Cd stress in WT duckweed. This study showed that NO level has been modified in NHX1 duckweed, which could be influcened by pH.

Regeneration of duckweed (Lemna turonifera) involves genetic molecular regulation and cyclohexane release.

Plant regeneration is important for vegetative propagation, detoxification and the obtain of transgenic plant. We found that duckweed regeneration could be enhanced by regenerating callus. However, very little is known about the molecular mechanism and the release of volatile organic compounds (VOCs). To gain a global view of genes differently expression profiles in callus and regenerating callus, genetic transcript regulation has been studied. Auxin related genes have been significantly down-regulated in regenerating callus. Cytokinin signal pathway genes have been up-regulated in regenerating callus. This result suggests the modify of auxin and cytokinin balance determines the regenerating callus. Volatile organic compounds release has been analysised by gas chromatography/ mass spectrum during the stage of plant regeneration, and 11 kinds of unique volatile organic compounds in the regenerating callus were increased. Cyclohexane treatment enhanced duckweed regeneration by initiating root. Moreover, Auxin signal pathway genes were down-regulated in callus treated by cyclohexane. All together, these results indicated that cyclohexane released by regenerating callus promoted duckweed regeneration. Our results provide novel mechanistic insights into how regenerating callus promotes regeneration.

Proliferation Cycle Causes Age Dependent Mitochondrial Deficiencies and Contributes to the Aging of Stem Cells.

In addition to chronological aging, stem cells are also subject to proliferative aging during the adult life span. However, the consequences of proliferative cycle and their contributions to stem cells aging have not been well investigated. Using Drosophila female germ line stem cells as a model, we found that the replication cycle leads to the age dependent decline of female fecundity, and is a major factor causing developmental abnormalities in the progeny of old females. The proliferative aging does not cause telomere shortening, but causes an accumulation of mitochondrial DNA (mtDNA) mutations or rearrangements at the control region. We propose that damaging mutations on mtDNA caused by accumulation of proliferation cycles in aged stem cells may disrupt mitochondrial respiration chain and impair mtDNA replication and represent a conserved mechanism underlying stem cell aging.

Coordination and fine motor control depend on Drosophila TRPγ.

Motor coordination is broadly divided into gross and fine motor control, both of which depend on proprioceptive organs. However, the channels that function specifically in fine motor control are unknown. Here we show that mutations in trpγ disrupt fine motor control while leaving gross motor proficiency intact. The mutants are unable to coordinate precise leg movements during walking, and are ineffective in traversing large gaps due to an inability in making subtle postural adaptations that are requisite for this task. TRPγ is expressed in proprioceptive organs, and is required in both neurons and glia for gap crossing. We expressed TRPγ in vitro, and found that its activity is promoted by membrane stretch. A mutation eliminating the Na(+)/Ca(2+) exchanger suppresses the gap-crossing phenotype of trpγ flies. Our findings indicate that TRPγ contributes to fine motor control through mechanical activation in proprioceptive organs, thereby promoting Ca(2+) influx, which is required for function.

Gr64f is required in combination with other gustatory receptors for sugar detection in Drosophila.

The mechanisms by which the fruit fly Drosophila melanogaster detects sweet compounds are poorly understood; however, a subset of the family of 68 gustatory receptors (Grs) has emerged as the key receptors. These seven transmembrane receptors include Gr5a and at least one member of the six genes in the Gr64 cluster (Gr64a), which are expressed in sugar-responsive neurons. Disruption of Gr5a prevents the detection of trehalose [1-3], whereas mutation of Gr64a impairs the responses to sucrose, maltose, and glucose [4, 5]. Recent studies suggest that these sugar receptors may require a coreceptor for function in vivo [4-6]; however, the identity of the putative coreceptor is not known. In the current work, we demonstrate that Gr64f is required in combination with Gr5a for the behavioral response to trehalose and for production of nerve responses to trehalose. Gr64f was also required in concert with Gr64a to rescue the defects in the sensitivities to sucrose, maltose, and glucose, resulting from deletion of the entire Gr64 cluster. These data suggest that Drosophila sugar receptors function as multimers and that Gr64f is required broadly as a coreceptor for the detection of sugars.

A Drosophila model for LRRK2-linked parkinsonism.

Mutations in the leucine-rich repeat kinase (LRRK2) gene cause late-onset autosomal dominant Parkinson's disease (PD) with pleiomorphic pathology. Previously, we and others found that expression of mutant LRRK2 causes neuronal degeneration in cell culture. Here we used the GAL4/UAS system to generate transgenic Drosophila expressing either wild-type human LRRK2 or LRRK2-G2019S, the most common mutation associated with PD. Expression of either wild-type human LRRK2 or LRRK2-G2019S in the photoreceptor cells caused retinal degeneration. Expression of LRRK2 or LRRK2-G2019S in neurons produced adult-onset selective loss of dopaminergic neurons, locomotor dysfunction, and early mortality. Expression of mutant G2019S-LRRK2 caused a more severe parkinsonism-like phenotype than expression of equivalent levels of wild-type LRRK2. Treatment with l-DOPA improved mutant LRRK2-induced locomotor impairment but did not prevent the loss of tyrosine hydroxylase-positive neurons. To our knowledge, this is the first in vivo"gain-of-function" model which recapitulates several key features of LRRK2-linked human parkinsonism. These flies may provide a useful model for studying LRRK2-linked pathogenesis and for future therapeutic screens for PD intervention.