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Recent studies suggest the necessity of understanding the interactive effects of predation and productivity on species coexistence and prey diversity. Models predict that coexistence of prey species with different competitive abilities can be achieved if inferior resource competitors are less susceptible to predation and if productivity and/or predation pressure are at intermediate levels. Hence, predator effects on prey diversity are predicted to be highly context dependent: enhancing diversity from low to intermediate levels of productivity or predation and reducing diversity of prey at high levels of productivity or predation. While several studies have examined the interactive effects of herbivory and productivity on primary producer diversity, experimental studies of such effects in predator-prey systems are rare. We tested these predictions using an aquatic field mesocosm experiment in which initial density of the zooplankton predator Notonecta undulata and productivity were manipulated to test their interactive effects on diversity of seven zooplankton, cladoceran species that were common in surrounding ponds. Two productivity levels were imposed via phosphorus enrichment at levels comparable to low and intermediate levels found within neighboring natural ponds. We used open systems to allow for natural dispersal and behaviorally-mediated numerical responses by the flight-capable predator. Effects of predators on zooplankton diversity depended on productivity level. At low and high productivity, prey species richness declined while at high productivity it showed a unimodal relationship with increasing the predator density. Effects of treatments were weaker when using Pielou's evenness index or the inverse Simpson index as measures of prey diversity. Our findings are generally consistent with model predictions in which predators can facilitate prey coexistence and diversity at intermediate levels of productivity and predation intensity. Our work also shows that the functional form of the relationship between prey diversity and predation intensity can be complex and highly dependent on environmental context.
Proteomics data from a study on whether mercury exposure alters B cell responsiveness to self-antigens by interfering with B cell receptor (BCR) signal transduction. These data show the effects of mercury on the protein tyrosine kinase SYK, a critical protein involved in regulation of the BCR signaling pathway. The raw data for quantitation of SYK phosphorylation status of selected sites were obtained using multiple reaction monitoring (MRM) on a TSQ triple quadrupole mass spectrometer.
Laboratory bioassays were conducted between 2014-2016 at Wayne State University in cooperation with USGS to determine if different species of cyanobacteria influence quagga mussel spawning and fertilization success. The data describes the algal cultures tested and their density/concentration, the number of individuals tested, and the spawning and fertilization success of quagga mussels exposed to the cyanobacteria and those that were not (control).
This study examines the whether there is a phylogenetic structure to such episodes of changes in encephalization across mammals. Researchers used phylogenetic techniques to analyze brain mass, body mass and encephalization quotient (EQ) among 630 extant mammalian species. All data on body mass and brain mass of mammals were collected from published literature sources, except for brain masses measured directly from post-mortem specimens the researchers' own collections, and have been entered into a MySQL database.
Speciation with gene flow may require adaptive divergence of multiple traits to generate strong ecologically based reproductive isolation. Extensive negative pleiotropy or physical linkage of genes in the wrong phase affecting these diverging traits may therefore hinder speciation, while genetic independence or “modularity” among phenotypic traits may reduce constraints and facilitate divergence. This study tested whether the genetics underlying two components of diapause life history, initial diapause intensity and diapause termination timing, constrain differentiation between sympatric hawthorn and apple-infesting host races of the fly Rhagoletis pomonella through analysis of 10,256 SNPs measured via genotyping-by-sequencing (GBS).
This study examined the relationship between clonal dynamics and population stability of natural Daphnia pulex populations experiencing seasonal environmental variation. It shows that the degree of asynchrony in a population's clonal dynamics is tightly linked to its population-level stability. Populations whose clonal abundances were more asynchronous were more stable temporally. Variation in asynchrony was related to variability in primary productivity, and experiments using clones from the study populations revealed significant genotype by environment interactions in response to food level.
Multiple cell types can be specified from a single pool of progenitors through the combinatorial activity of transcriptional regulators, which activate distinct developmental programs to establish different cell fates. The zinc finger transcription factor Glass is required for neuronal progenitors in the Drosophila eye imaginal disc to acquire a photoreceptor identity. Glass is also expressed in non-neuronal cone and pigment cells, but its role in these cells is unknown. To examine how Glass activity is affected by the cellular context, the researchers misexpressed it in different tissues. When expressed in neuroblasts of the larval brain or in epithelial cells of the wing disc, Glass activated both a common core set of target genes and distinct gene sets specific to each tissue. In addition to photoreceptor-specific genes, Glass induced markers of cone and pigment cells. Cell type-specific glass mutations generated in cone or pigment cells using somatic CRISPR revealed autonomous developmental defects, and expressing Glass specifically in these cells partially rescued glass mutant phenotypes. Glass thus acts in both neuronal and non-neuronal cells to promote their differentiation into functional components of the eye, suggesting that it is a determinant of organ identity.
This study reports the sequencing and manual annotation of the Gerris buenoi (G. buenoi) genome; the first water strider genome to be sequenced thus far. The size of the G. buenoi genome is approximately 1,000 Mb, and this sequencing effort has recovered 20,949 predicted protein-coding genes. Manual annotation uncovered a number of local (tandem and proximal) gene duplications and expansions of gene families known for their importance in a variety of processes associated with morphological and physiological adaptations to a water surface lifestyle.
Elucidating the cold tolerance mechanism of Paeonia lactiflora, which is one of the most valuable ornamental and medicinal plants in Asia, fundamentally impacts its breeding and production. The glycerol-3-phosphate acyltransferase (GPAT) gene plays a pivotal role in cold resistance in a variety of plant species. The researchers in this study cloned the P. lactiflora GPAT gene, determined its expression pattern, and tested its role in cold resistance. They obtained the full-length P. lactiflora GPAT gene using tissue-cultured seedlings and real-time polymerase chain reaction and rapid amplification of cDNA ends analyses. They named this gene PlGPAT in P. lactiflora. Phylogenetic analysis indicates that the PlGPAT gene is closely related with the GPAT genes in core eudicots. The phylogenetic tree containing 31 angiosperm species based on GPAT protein sequences is largely consistent with the known phylogeny in flowering plants. They conducted a time-course PlGPAT expression analysis and demonstrated that PlGPAT expression is correlated with low-temperature stress. Our results suggest that the PlGPAT gene plays an important role in regulating cold resistance in P. lactiflora.
B-cells play a pivotal role in several autoimmune diseases, including patients with immune-mediated neurological disorders (PIMND), such as neuromyelitis optica (NMO), multiple sclerosis (MS), and myasthenia gravis (MG). Targeting B-cells has been an effective approach in ameliorating both central and peripheral autoimmune diseases. However, there is a paucity of literature on the safety of continuous B-cell depletion over a long period of time. The aim of this study was to examine the long-term safety, incidence of infections, and malignancies in subjects receiving continuous therapy with a B-cell depleting agent rituximab over at least 3 years or longer. This was a retrospective study involving PIMND who received continuous cycles of rituximab infusions every 6 to 9 months for up to 7 years. The incidence of infection related adverse events (AE), serious adverse events (SAE), and malignancies were observed.