Synaptic wiring motifs in posterior parietal cortex support decision-making.

The posterior parietal cortex exhibits choice-selective activity during perceptual decision-making tasks1-10. However, it is not known how this selective activity arises from the underlying synaptic connectivity. Here we combined virtual-reality behaviour, two-photon calcium imaging, high-throughput electron microscopy and circuit modelling to analyse how synaptic connectivity between neurons in the posterior parietal cortex relates to their selective activity. We found that excitatory pyramidal neurons preferentially target inhibitory interneurons with the same selectivity. In turn, inhibitory interneurons preferentially target pyramidal neurons with opposite selectivity, forming an opponent inhibition motif. This motif was present even between neurons with activity peaks in different task epochs. We developed neural-circuit models of the computations performed by these motifs, and found that opponent inhibition between neural populations with opposite selectivity amplifies selective inputs, thereby improving the encoding of trial-type information. The models also predict that opponent inhibition between neurons with activity peaks in different task epochs contributes to creating choice-specific sequential activity. These results provide evidence for how synaptic connectivity in cortical circuits supports a learned decision-making task.

The Cousa objective: a long-working distance air objective for multiphoton imaging in vivo.

Multiphoton microscopy can resolve fluorescent structures and dynamics deep in scattering tissue and has transformed neural imaging, but applying this technique in vivo can be limited by the mechanical and optical constraints of conventional objectives. Short working distance objectives can collide with compact surgical windows or other instrumentation and preclude imaging. Here we present an ultra-long working distance (20 mm) air objective called the Cousa objective. It is optimized for performance across multiphoton imaging wavelengths, offers a more than 4 mm2 field of view with submicrometer lateral resolution and is compatible with commonly used multiphoton imaging systems. A novel mechanical design, wider than typical microscope objectives, enabled this combination of specifications. We share the full optical prescription, and report performance including in vivo two-photon and three-photon imaging in an array of species and preparations, including nonhuman primates. The Cousa objective can enable a range of experiments in neuroscience and beyond.

Structured cerebellar connectivity supports resilient pattern separation.

The cerebellum is thought to help detect and correct errors between intended and executed commands1,2 and is critical for social behaviours, cognition and emotion3-6. Computations for motor control must be performed quickly to correct errors in real time and should be sensitive to small differences between patterns for fine error correction while being resilient to noise7. Influential theories of cerebellar information processing have largely assumed random network connectivity, which increases the encoding capacity of the network's first layer8-13. However, maximizing encoding capacity reduces the resilience to noise7. To understand how neuronal circuits address this fundamental trade-off, we mapped the feedforward connectivity in the mouse cerebellar cortex using automated large-scale transmission electron microscopy and convolutional neural network-based image segmentation. We found that both the input and output layers of the circuit exhibit redundant and selective connectivity motifs, which contrast with prevailing models. Numerical simulations suggest that these redundant, non-random connectivity motifs increase the resilience to noise at a negligible cost to the overall encoding capacity. This work reveals how neuronal network structure can support a trade-off between encoding capacity and redundancy, unveiling principles of biological network architecture with implications for the design of artificial neural networks.

Optimized gamma radiation produces physiological and morphological changes that improve seed yield in wheat.

To study the effect of gamma radiation on various morphological and agronomic characters of bread wheat (Triticum aestivum L.), seeds were subjected to different gamma radiation doses; and selected M5 and M6 generation lines were evaluated. The optimum doses to induce desirable changes in bread wheat were 100-200 Gy. Seed loss decreased while grain yield, yield components, fertile florets number, biological yield, plant height, harvest index and flag leaf area increased in all mutant lines. Shear strength increased in many lines. Selected mutant lines also showed reduced seed shattering that can greatly reduce seed loss at harvest. Some new phenotypic characters such as the appearance of bristles on the glume, important for drought tolerance, two spikelets at each rachis and more fertile florets at each spikelet. These can greatly increase yield, as seen in some mutant lines. Also, some physiological characteristics including photosynthetic rate, stomatal conductance, water use efficiency, and chlorophyll content improved in some mutant lines. About 95.8% of the total variation in grain yield was explained by three selected variables: flag leaf area, number of seeds per spike, and spike number per plant. Grain yield increased more than 45% in some mutant lines the highest ever reported using this approach to the genetic improvement of wheat. Wheat grain yield has increased 2.2 times in the last 50 years, which indicates that if mutagens are optimally used and the selection is carefully performed as described herein, it is possible to improve important economic traits, in a much shorter time. Supplementary Information: The online version contains supplementary material available at 10.1007/s12298-022-01225-0.

Organization of the gravity-sensing system in zebrafish.

Motor circuits develop in sequence from those governing fast movements to those governing slow. Here we examine whether upstream sensory circuits are organized by similar principles. Using serial-section electron microscopy in larval zebrafish, we generated a complete map of the gravity-sensing (utricular) system spanning from the inner ear to the brainstem. We find that both sensory tuning and developmental sequence are organizing principles of vestibular topography. Patterned rostrocaudal innervation from hair cells to afferents creates an anatomically inferred directional tuning map in the utricular ganglion, forming segregated pathways for rostral and caudal tilt. Furthermore, the mediolateral axis of the ganglion is linked to both developmental sequence and neuronal temporal dynamics. Early-born pathways carrying phasic information preferentially excite fast escape circuits, whereas later-born pathways carrying tonic signals excite slower postural and oculomotor circuits. These results demonstrate that vestibular circuits are organized by tuning direction and dynamics, aligning them with downstream motor circuits and behaviors.

Different acyl-CoA:diacylglycerol acyltransferases vary widely in function, and a targeted amino acid substitution enhances oil accumulation.

Triacylglycerols (TAGs) are the major component of plant storage lipids such as oils. Acyl-CoA:diacylglycerol acyltransferase (DGAT) catalyzes the final step of the Kennedy pathway, and is mainly responsible for plant oil accumulation. We previously found that the activity of Vernonia DGAT1 was distinctively higher than that of Arabidopsis and soybean DGAT1 in a yeast microsome assay. In this study, the DGAT1 cDNAs of Arabidopsis, Vernonia, soybean, and castor bean were introduced into Arabidopsis. All Vernonia DGAT1-expressing lines showed a significantly higher oil content (49% mean increase compared with the wild-type) followed by soybean and castor bean. Most Arabidopsis DGAT1-overexpressing lines did not show a significant increase. In addition to these four DGAT1 genes, sunflower, Jatropha, and sesame DGAT1 genes were introduced into a TAG biosynthesis-defective yeast mutant. In the yeast expression culture, DGAT1s from Arabidopsis, castor bean, and soybean only slightly increased the TAG content; however, DGAT1s from Vernonia, sunflower, Jatropha, and sesame increased TAG content >10-fold more than the former three DGAT1s. Three amino acid residues were characteristically common in the latter four DGAT1s. Using soybean DGAT1, these amino acid substitutions were created by site-directed mutagenesis and substantially increased the TAG content.

Response of Prosopis farcta to gradually increased soil copper and cadmium levels based on an integrated investigation.

The impact of gradually increased soil levels of copper (Cu) and cadmium (Cd) on the medicinal plant, Prosopis farcta, irrigated with metal-enriched water was determined. Plants were treated with 2.54, 5.08, 10.16, and 20.32 µg mL-1 for Cu2+ and 6.13, 12.26, 24.52, and 49 µg mL-1 for Cd2+. The rate of phytoremediation was measured by bioconcentration factor (BCF) and the relative bioconcentration factor (RBCF). The movement of metal ions from roots to shoots was calculated as the Translocation Factor (TF). The exposure of plants to Cd or Cu decreased plant growth and increased Cd and Cu concentration in their shoots and roots. The weight of both shoots and roots decreased linearly with the increase of Cu and Cd contents in roots and shoots. Cd was more toxic than Cu as expected. The water content of shoots and roots decreased linearly as heavy metal levels increased. Prosopis farcta can take up Cu and Cd in both Cu- and Cd-contaminated soils but was more capable for transporting Cd from roots to shoots rather than Cu although more Cu is taken up by roots. Prosopis farcta is a natural accumulator of Cu and Cd and can be used in phytoremediation.CONCISE NOVEL ASPECTS OF THIS STUDYThis is the first report to show that the medicinal plant Prosopis farcta is an accumulator for Cu and Cd.This was determined by gradual addition of the metals to the soil via irrigation by heavy metal-polluted water which can provide an opportunity for the plant to develop a metal-resistance mechanism.Choosing suitable plant species for heavy metal accumulation is a critical step for successful phytoremediation of heavy metal pollutants.CORE IDEASProsopis farcta is of interest as a medicinal plant.P. farcta can take up Cu and Cd in both Cu- and Cd-contaminated soils.P. farcta transports more Cd from roots to shoots but more Cu is taken up.

Late-Season Nitrogen Applications Increase Soybean Yield and Seed Protein Concentration.

Low seed and meal protein concentration in modern high-yielding soybean [Glycine max L. (Merr.)] cultivars is a major concern but there is limited information on effective cultural practices to address this issue. In the objective of dealing with this problem, this study conducted field experiments in 2019 and 2020 to evaluate the response of seed and meal protein concentrations to the interactive effects of late-season inputs [control, a liquid Bradyrhizobium japonicum inoculation at R3, and 202 kg ha-1 nitrogen (N) fertilizer applied after R5], previous cover crop (fallow or cereal cover crop with residue removed), and short- and full-season maturity group cultivars at three U.S. locations (Fayetteville, Arkansas; Lexington, Kentucky; and St. Paul, Minnesota). The results showed that cover crops had a negative effect on yield in two out of six site-years and decreased seed protein concentration by 8.2 mg g-1 on average in Minnesota. Inoculant applications at R3 did not affect seed protein concentration or yield. The applications of N fertilizer after R5 increased seed protein concentration by 6 to 15 mg g-1, and increased yield in Arkansas by 13% and in Minnesota by 11% relative to the unfertilized control. This study showed that late-season N applications can be an effective cultural practice to increase soybean meal protein concentration in modern high-yielding cultivars above the minimum threshold required by the industry. New research is necessary to investigate sustainable management practices that increase N availability to soybeans late in the season.

High plasticity in marmoset monkey vocal development from infancy to adulthood.

The vocal behavior of human infants undergoes marked changes across their first year while becoming increasingly speech-like. Conversely, vocal development in nonhuman primates has been assumed to be largely predetermined and completed within the first postnatal months. Contradicting this assumption, we found a dichotomy between the development of call features and vocal sequences in marmoset monkeys, suggestive of a role for experience. While changes in call features were related to physical maturation, sequences of and transitions between calls remained flexible until adulthood. As in humans, marmoset vocal behavior developed in stages correlated with motor and social development stages. These findings are evidence for a prolonged phase of plasticity during marmoset vocal development, a crucial primate evolutionary preadaptation for the emergence of vocal learning and speech.

Geometric deep learning enables 3D kinematic profiling across species and environments.

Comprehensive descriptions of animal behavior require precise three-dimensional (3D) measurements of whole-body movements. Although two-dimensional approaches can track visible landmarks in restrictive environments, performance drops in freely moving animals, due to occlusions and appearance changes. Therefore, we designed DANNCE to robustly track anatomical landmarks in 3D across species and behaviors. DANNCE uses projective geometry to construct inputs to a convolutional neural network that leverages learned 3D geometric reasoning. We trained and benchmarked DANNCE using a dataset of nearly seven million frames that relates color videos and rodent 3D poses. In rats and mice, DANNCE robustly tracked dozens of landmarks on the head, trunk, and limbs of freely moving animals in naturalistic settings. We extended DANNCE to datasets from rat pups, marmosets, and chickadees, and demonstrate quantitative profiling of behavioral lineage during development.

Reconstruction of motor control circuits in adult Drosophila using automated transmission electron microscopy.

To investigate circuit mechanisms underlying locomotor behavior, we used serial-section electron microscopy (EM) to acquire a synapse-resolution dataset containing the ventral nerve cord (VNC) of an adult female Drosophila melanogaster. To generate this dataset, we developed GridTape, a technology that combines automated serial-section collection with automated high-throughput transmission EM. Using this dataset, we studied neuronal networks that control leg and wing movements by reconstructing all 507 motor neurons that control the limbs. We show that a specific class of leg sensory neurons synapses directly onto motor neurons with the largest-caliber axons on both sides of the body, representing a unique pathway for fast limb control. We provide open access to the dataset and reconstructions registered to a standard atlas to permit matching of cells between EM and light microscopy data. We also provide GridTape instrumentation designs and software to make large-scale EM more accessible and affordable to the scientific community.

Ozone-induced lipid changes in the wildtype and toc132toc120 heterozygote mutant of Arabidopsis thaliana.

We measured the fatty acids and lipid content in the wildtype and toc132toc120 heterozygote mutant of Arabidopsis thaliana that were exposed to elevated levels of ozone. The goal was to assess whether a defective atToc132/120 receptor would alter the mutant's response to ozone-induced stress. Increased malondialdehyde (MDA) levels were measured in wildtype plants that were exposed to ozone for 3 h and left in an ozone-free environment for 21 h. The increased levels of MDA were not positively correlated with changes in the levels of triunsaturated fatty acids from which MDA is derived. In both the wildtype and mutant plants, absolute amounts of the glycerolipids were not altered by ozone treatment. The untreated mutant, however, accumulated decreased levels of chloroplast lipids and triunsaturated fatty acids. In ozone-treated wildtype, the levels of 16:3 were significantly decreased and this was mirrored by decreased levels of TOC132 and FAD5 transcripts, and increased levels of SP1 E3 ligase transcripts. These data suggest a possible increase in protein ubiquitination under ozone-induced stress. In contrast, in ozone-treated mutant, the FAD5 transcripts accumulated at the control level. The untreated mutant, however, accumulated significantly increased levels of CAT1 and FAD7 transcripts, which indicates that a defective chloroplast receptor induced cellular stress. In ozone-treated wildtype, there was a small increase in 34:6-phosphatidic acid, which indicates that a small amount of the chloroplast-derived MGDG was degraded in response to ozone-induced stress. Overall, these data indicate that the wildtype and mutant responded differently in lipid composition and oxidation to ozone-induced stress.

Central Vestibular Tuning Arises from Patterned Convergence of Otolith Afferents.

As sensory information moves through the brain, higher-order areas exhibit more complex tuning than lower areas. Though models predict that complexity arises via convergent inputs from neurons with diverse response properties, in most vertebrate systems, convergence has only been inferred rather than tested directly. Here, we measure sensory computations in zebrafish vestibular neurons across multiple axes in vivo. We establish that whole-cell physiological recordings reveal tuning of individual vestibular afferent inputs and their postsynaptic targets. Strong, sparse synaptic inputs can be distinguished by their amplitudes, permitting analysis of afferent convergence in vivo. An independent approach, serial-section electron microscopy, supports the inferred connectivity. We find that afferents with similar or differing preferred directions converge on central vestibular neurons, conferring more simple or complex tuning, respectively. Together, these results provide a direct, quantifiable demonstration of feedforward input convergence in vivo.

Generation and Characterization of a Soybean Line with a Vernonia galamensis Diacylglycerol Acyltransferase-1 Gene and a myo-Inositol 1-Phosphate Synthase Knockout Mutation.

Soybean (Glycine max) meal is an important protein source. Soybean meal with lower phytate and oligosaccharides improves meal quality. A single recessive mutation in soybean myo-inositol 1-phosphate synthase (Gm-lpa-TW75-1) confers a seed phenotype with low phytate and increased inorganic phosphate. The mutant was crossed with high oil lines expressing a diacylglycerol acyltransferase1 (DGAT) gene from Vernonia galamensis (VgD). Gm-lpa-TW75-1 X VgD, designated GV, has 21%, and 22% oil and 41% and 43% protein from field and greenhouse seed production, respectively. No significant differences were found in mineral concentrations except for Fe which was 229 µg/g dry mass for GV followed by 174.3 for VgD and 162 for Gm-lpa-TW75-1. Phosphate (Pi) is higher in Gm-lpa-TW75-1 as expected at 5 mg/g, followed by GV at 1.6 mg/g whereas Jack, VgD, and Taiwan75 have about 0.3 mg/g. The Gm-lpa-TW75-1 line has the lowest phytate concentration at 1.4 mg/g followed by GV with 1.8 mg/g compared to Taiwan75, VgD, and Jack with 2.5 mg/g. This work describes a high oil and protein soybean line, GV, with increased Pi and lower phytate which will increase the nutritional value for human and animal feed.

Endoplasmic reticulum retention signaling and transmembrane channel proteins predicted for oilseed ω3 fatty acid desaturase 3 (FAD3) genes.

Oilseed crop oils contain a variety of unsaturated fatty acids that are synthesized and regulated by fatty acid desaturases (FADs). In this study, 14 FAD3 (ω3 desaturase) protein sequences from oilseeds are analyzed and presented through the application of several computational tools. The results indicated a close relationship between Brassica napus and Camelina sativa, as well as between Salvia hispanica and Perilla frutescens FAD3s, due to a high similarity in codon preferences in codon usage clusters and the phylogenetic tree. The cis-acting element results reveal that the seed-specific promoter region of BnFAD3 contains the critical conserved boxes such as HSE and ABRE, which are involved in responsiveness to heat stress and abscisic acid. The presence of the aforementioned conserved boxes may increase cold acclimation as well as tolerance to drought and high salinity. Omega(ω)3 desaturases contain a Skn-1 motif which is a cis-acting regulatory element required involved in endosperm development. In oilseed FAD3s, leucine is the most repeated amino acid in FAD3 proteins. The study conveyed that B. napus, Camelina sativa, Linum usitatissimum, Vernicia fordii, Gossypium hirsutum, S. hispanica, Cannabis sativa, and P. frutescens have retention signal KXKXX/XKXX at their c-terminus sites, which is one of the most important characteristics of FADs. Additionally, it was found that BnFAD3 is a transmembrane protein that can convert ω6 to ω3 fatty acids and may simultaneously act as a potassium ion channel in the ER.

Lamellar projections in the endolymphatic sac act as a relief valve to regulate inner ear pressure.

The inner ear is a fluid-filled closed-epithelial structure whose function requires maintenance of an internal hydrostatic pressure and fluid composition. The endolymphatic sac (ES) is a dead-end epithelial tube connected to the inner ear whose function is unclear. ES defects can cause distended ear tissue, a pathology often seen in hearing and balance disorders. Using live imaging of zebrafish larvae, we reveal that the ES undergoes cycles of slow pressure-driven inflation followed by rapid deflation. Absence of these cycles in lmx1bb mutants leads to distended ear tissue. Using serial-section electron microscopy and adaptive optics lattice light-sheet microscopy, we find a pressure relief valve in the ES comprised of partially separated apical junctions and dynamic overlapping basal lamellae that separate under pressure to release fluid. We propose that this lmx1-dependent pressure relief valve is required to maintain fluid homeostasis in the inner ear and other fluid-filled cavities.

Pan-neuronal calcium imaging with cellular resolution in freely swimming zebrafish.

Calcium imaging with cellular resolution typically requires an animal to be tethered under a microscope, which substantially restricts the range of behaviors that can be studied. To expand the behavioral repertoire amenable to imaging, we have developed a tracking microscope that enables whole-brain calcium imaging with cellular resolution in freely swimming larval zebrafish. This microscope uses infrared imaging to track a target animal in a behavior arena. On the basis of the predicted trajectory of the animal, we applied optimal control theory to a motorized stage system to cancel brain motion in three dimensions. We combined this motion-cancellation system with differential illumination focal filtering, a variant of HiLo microscopy, which enabled us to image the brain of a freely swimming larval zebrafish for more than an hour. This work expands the repertoire of natural behaviors that can be studied with cellular-resolution calcium imaging to potentially include spatial navigation, social behavior, feeding and reward.