Bat species richness and abundance in tropical rain forest fragments and in agricultural habitats at Los Tuxtlas, Mexico

Faced with the rapid and extensive conversion of tropical rain forests to pasture lands and agricultural fields and with the need to preserve the remaining mammalian fauna, it is imperative to determine how the different species that form the mammalian community have responded to the anthropogenic alterations of their natural habitats To provide data in this direction, we sampled bats m 45 forest islands, m 20 agricultural habitats representing five types of vegetation (cocoa, coffee, mixed, citrus and allspice), in four live-fence sites and in four pasture sites at Los Tuxtlas, Veracruz, Mexico Sampling effort resulted in the capture of 2587 bats representing 35 species In forest habitats we detected 32 species We did not capture any bats at the four pasture sites, but the at the other agricultural habitats studied, we captured 38% of the bats and 77% of the species recorded Thirty-four percent of the species recorded were present at the live-fence habitats Isolating distance was an important variable influencing species richness in forests and in agricultural habitats Only 10% of the species recorded occurred m all the habitats studied, but 77% of the species occurred m a habitat other than ram forest Recaptures of bats indicated inter habitat movements in the fragmented landscape We discuss the conservation value for the bat fauna of agricultural islands of vegetation as elements reducing isolating distances among forest fragments     

The dentary of hadrosauroid dinosaurs: evolution through heterochrony

The near-global distribution of hadrosaurid dinosaurs during the Cretaceous has been attributed to mastication, a behaviour commonly recognized as a mammalian adaptation. Its occurrence in a non-mammalian lineage should be accompanied by the evolution of several morphological modifications associated with food acquisition and processing. This study investigated morphological variation in the dentary, a major element of the hadrosauroid lower jaw. Eighty-four hadrosauroid dentaries were subjected to geometric morphometric and statistical analyses to investigate their taxonomic, ontogenetic, and individual variation. Results suggest increased food acquisition and processing efficiency in saurolophids through a complex pattern of evolutionary and growth-related changes. The edentulous region grew longer relative to dentary length, allowing for food acquisition specialization anteriorly and processing posteriorly, and became ventrally directed, possibly associated with foraging low-growing vegetation, especially in younger individuals. The saurolophid coronoid process became anteriorly directed and relatively more elongate, with an expanded apex, increasing moment arm length, with muscles pulling the jaw more posteriorly, increasing mechanical advantage. During growth, all hadrosauroids underwent anteroposterior dental battery elongation by the addition of teeth, and edentulous region ventralization decreased. The dental battery became deeper in saurolophids by increasing the number of teeth per tooth family. The increased coronoid process anterior inclination and relative edentulous region elongation in saurolophids are hypothesized to have evolved through hypermorphosis and/or acceleration, peramorphic heterochronic processes; the development of an anteroposteriorly shorter but dorsoventrally taller saurolophid dentary, is probably due to post-displacement in dental battery elongation and edentulous region decreased ventral orientation, a paedomorphic heterochronic process.     

Influence of seasonal variation to the population growth and ecophysiology of Typha domingensis (Typhaceae)

Journal of Plant Research - Precipitation is an important climatic element that defines the hydrological regime, and its seasonal variation produces annual dry and wet periods in some areas. This...     

Human pluripotent stem cell-derived extracellular vesicles: From now to the future

Extracellular vesicles (EVs) are nanometric particles that enclose cell-derived bioactive molecules in a lipid bilayer and serve as intercellular communication tools. Accordingly, in various biological contexts, EVs are reported to engage in immune modulation, senescence, and cell proliferation and differentiation. Therefore, EVs could be key elements for potential off-the-shelf cell-free therapy. Little has been studied regarding EVs derived from human pluripotent stem cells (hPSC-EVs), even though hPSCs offer good opportunities for induction of tissue regeneration and unlimited proliferative ability. In this review article, we provide an overview of studies using hPSC-EVs, focusing on identifying the conditions in which the cells are cultivated for the isolation of EVs, how they are characterized, and applications already demonstrated. The topics reported in this article highlight the incipient status of the studies in the field and the significance of hPSC-EVs’ prospective applications as PSC-derived cell-free therapy products.     

First chromosome scale genomes of ithomiine butterflies (Nymphalidae: Ithomiini): Comparative models for mimicry genetic studies

The ithomiine butterflies (Nymphalidae: Danainae) represent the largest known radiation of Müllerian mimetic butterflies. They dominate by number the mimetic butterfly communities, which include species such as the iconic neotropical Heliconius genus. Recent studies on the ecology and genetics of speciation in Ithomiini have suggested that sexual pheromones, colour pattern and perhaps hostplant could drive reproductive isolation. However, no reference genome was available for Ithomiini, which has hindered further exploration on the genetic architecture of these candidate traits, and more generally on the genomic patterns of divergence. Here, we generated high-quality, chromosome-scale genome assemblies for two Melinaea species, M. marsaeus and M. menophilus, and a draft genome of the species Ithomia salapia. We obtained genomes with a size ranging from 396 to 503 Mb across the three species and scaffold N50 of 40.5 and 23.2 Mb for the two chromosome-scale assemblies. Using collinearity analyses we identified massive rearrangements between the two closely related Melinaea species. An annotation of transposable elements and gene content was performed, as well as a specialist annotation to target chemosensory genes, which is crucial for host plant detection and mate recognition in mimetic species. A comparative genomic approach revealed independent gene expansions in ithomiines and particularly in gustatory receptor genes. These first three genomes of ithomiine mimetic butterflies constitute a valuable addition and a welcome comparison to existing biological models such as Heliconius, and will enable further understanding of the mechanisms of adaptation in butterflies.     

Gene expression associated with in vivo induction of early phase-long-term potentiation (LTP) in the hippocampal mossy fiber-Cornus Ammonis (CA)3 pathway.

Affymetrix microarray technology was used to characterize whole-hippocampus gene expression associated with in vivo N-methyl-D-aspartate (NMDA)-R-independent long-term potentiation (LTP) in the mossy fiber (MF)-Cornus Ammonis (CA)3 pathway of adult male F344 rats. Acute MF responses were evoked by stimulation of the MF bundle and recorded in stratum lucidum of CA3. Following recording of baseline responses at 0.05 Hz, animals received either CPP (NMDA-R antagonist, 10 mg/kg) or naloxone (opioid-R antagonist, 10 mg/kg). LTP was induced by two 100 Hz 1-sec trains at the intensity sufficient to evoke 50% of the maximal response. Responses were collected for an additional hour. In controls, MF responses were collected at 0.05 Hz for 1 hr, but 100 Hz trains were not delivered. Hippocampi were harvested prior to total RNA isolation. Fragmented cRNA was hybridized to a rat U34 neurobiology array. F344 rats exhibited characteristic LTP in the presence of CPP and LTP blockade in the presence of naloxone. As a result, genes associated with both NMDA-independent LTP and naloxone-induced blockade were identified. These include genes involved in transmitter transport, intracellular messengers, growth factors and ion channels. Up-regulated include NMDA-R2D, neuropeptide Y (NPY), proenkephalin, BDNF and NGFR. Down-regulated genes include IGF-1 and GABA-B.     

Chloride secretion in the submandibular gland of adult and early postnatal rats studied by X-ray microanalysis

Submandibular acinar cells of 1-day-old, 7-day-old, and adult rats were analyzed with X-ray microanalysis after stimulation with carbachol for different time periods (2–7 min). In unstimulated animals, marked differences in elemental content between compartments could be observed: secretory granules had a higher Ca and lower P and K content than other cell compartments. Comparison between different age groups showed significant differences for Ca, which increased with age in all compartments; Mg increased with age in the secretory granules and the apical cytoplasm. Only the glands from adult animals showed a significant effect of cholinergic stimulation: a transient decrease in Cl and K. The Cl concentration in the secretory granules decreased to 60% of the control value, which suggests that the granules release Cl upon stimulation. In young animals, no or little change in elemental distribution was observed after stimulation. This may indicate that Cl-secretion mechanisms are much less prominent in young animals. The ultrastructure of submandibular secretory granules depends on the preparation method: condensed and electrondense in freeze-substituted unfixed tissue, decondensed and more translucent in aldehyde-fixed tissue. This may indicate that the granules can transport water, and swell during the process of aldehyde fixation.     

Somatic embryogenesis and plant regeneration from isolated protoplasts of Lavatera thuringiaca

Embryogenic cell suspensions of Lavatera thuringiaca L. were established from leaf petiole and shoot regeneration was achieved when cells were plated on medium without growth regulators. We tested three methods for protoplast culture, isolated from a one-year old embryogenic cell suspension, to determine the best conditions for L. thuringiaca protoplast culture and shoot regeneration. The highest protoplast plating efficiency was obtained with the agaroseembedded method, reaching 30%, while the nursing culture method gave 5% when the protoplasts were plated over Whatman paper No. 2. However, the same nursing culture failed to produce protoplast-derived microcalluses when the protoplasts were plated on a nitrocellulose filter. The liquid thin layer method gave the lowest plating efficiency with only 0.5%. Shoot regeneration from protoplast-derived microcalluses was achieved in two steps; first, globular embryo development was favored in medium low in auxin (2,4-d and BA at 0.01 and 0.05 mg 1^-1, respectively), second, the globular embryos further differentiate into shoots in medium without growth regulators or in medium containing GA₃ (0.5 to 1.0 mg 1^-1).Abbreviations 2,4-d 2,4-dichlorophenoxyacetic acid - BA benzyladenine - GA₃ gibberellic acid - NAA -naphthaleneacetic acid - IBA indole-3-butyric acid