Local adaptation in populations of a Brachionus group plicatilis cryptic species inhabiting three deep crater lakes in Central Mexico

1. Salinity is a strong selective force for many aquatic organisms, affecting both ecological and evolutionary processes. Most of our knowledge on the effects of salinity on rotifers in the Brachionus plicatilis species complex is based mainly on populations from waterbodies that experience broad environmental changes both seasonally and annually. We tested the hypothesis that, despite the supposedly high potential for gene flow among rotifers inhabiting neighbouring environments, constant salinity has promoted local adaptation, genetic population divergence and even cryptic speciation in B. plicatilis complex populations from three deep maar lakes of distinct salinities [1.1, 6.5 and 9.0 g L^?1 total dissolved solids (TDS)] in Central Mexico. 2. To look for local adaptation, we performed common garden experiments to test the effect of different salinities on population density and intrinsic growth rate (r). Then, we evaluated the genetic divergence by sequencing the cytochrome c oxidase subunit I (COI) gene and performed reproductive trials to assess the potential gene flow among the three populations and with other closely related B. plicatilis complex species. 3. We confirmed that the rotifer populations have phenotypic plasticity in tolerance of salinity, but only rotifers from the least saline lake are adapted to low salinity. Among the populations, sequence divergence at COI was very low (just a single haplotype was found), suggesting a persistent founder effect from a relatively recent single colonisation event and a subsequent dispersal from one lake to the others, and a very restricted immigration rate. In the phylogenetic analysis, rotifers from this area of Mexico clustered in the same clade with the middle‐sized species Brachionus ibericus and B. sp. ‘Almenara’. Mexican rotifers showed successful recognition, copulation and formation of hybrids among them, but interpopulation breeding with the Spanish B. ibericus and B. sp. ‘Almenara’ was unsuccessful. 4. We conclude that the B. plicatilis complex populations from these three lakes belong to a new biological species not yet described (presently named B. sp. ‘Mexico’). To our knowledge, this is the first report of local adaptation of a natural B. plicatilis complex population living in freshwater conditions (1.1 g L^?1 TDS).     

Kv7 channel modulators reduce the stress-induced hyperthermia response and cause locomotor sedation in rats

Rationale

Kv7 channels (KCNQ) are potassium ion channels that are important in controlling neuronal excitability, which have been implicated in psychiatric disorders. Specifically, a role for Kv7 channels in anxiety processes has been proposed.

Objectives

The main aim of this study was to investigate possible anxiolytic effects of Kv7 channel modulators in rats applying the stress-induced hyperthermia (SIH) paradigm, a preclinical paradigm, which uses the autonomic stress-induced rise in body temperature as a readout parameter of stress.

Results

The non-selective Kv7.2–5 channel positive allosteric modulators (PAMs) flupirtine and retigabine reduced the SIH response and basal body temperature with concomitant locomotor sedation. Administration of the Kv7.4/Kv7.5 channel negative allosteric modulator R-BMS204352 prior to injection with flupirtine did not antagonize the effects on body temperature and locomotor activity. Administration of the Kv7.4/Kv7.5 preferential PAM S-BMS204352 only modestly affected basal body temperature but did not affect the SIH response or locomotor activity levels.

Conclusions

The present study supports a role of Kv7.2/Kv7.3 channels in anxiety reduction, hypothermia and sedation, whereas preferential activation of Kv7.4/Kv7.5 channels only modestly affected body temperature and locomotor activity. Thus, the effects of Kv7 channel openers may be dissociated with regard to the contribution of different Kv7 subunits and Kv7 channel isoforms.     

Molecular differentiation of Peroxysome proliferator activated receptor coactivator-1 among different breeds of Bubalus bubalis

Peroxysome proliferator activated receptor coactivator-1 gene (PPARGC1A) is a positional and functional candidate gene for milk fat yield. It has key role in energy, fat and glucose metabolism. Single nucleotide polymorphisms (SNPs) in Exon-8 of PPARGC1A are reported to be associated with milk fat yield in dairy cattle. In the present investigation PPARGC1A was partially amplified (around 767bp) by designing gene specific primer and confirm by sequencing the amplicon and its comparison with the PPARGC1A gene of bovine. Comparative study of PPARGC1A among different breeds of buffaloes reveals different level of mutations with respect to its gene sequence 0.013-1.69% and protein sequence 0.42% to 2.99%, Similarly the protein structures modeled from their sequences were compared by structural superposition that shows variations (RMSD) from 0.736 to 1.507. Furthermore, the sequences were used to generate a dendrogram. It reveals that Murrah and reference are very close to each other, similarly Toda, Bhadawari and Surti are closely related, whereas Pandharpuri is separated from both the cluster. Especially the variations are more at the binding site of this protein that may be the cause that different breeds have different percentage of milk fat. Further study is underway to detect polymorphism and associate them with milk fat related traits in buffalo.     

5'-nucleotidase activity in the spinning gland cells of Diacrisis obliqua (Arctiidae: Lepidoptera)

5'-nucleotidase activity in the spinning gland cells of an Indian moth, Diacrisia obliqua has been studied for the first time during prefunctional, functional and postfunctional phases of development. The enzyme seems to play an active role in the metabolism of silk secretion. Differential utilization of 5'-nucleotidase substrate in the growing and degenerating cells has been studied and discussed.     

Structure and histochemistry of the dermis of a chequered water snake, Natrix piscator

The histology and the protein, carbohydrate, lipid and enzyme histochemistry of the dermis of the chequered water snake, Natrix piscator , have been examined throughout the sloughing cycle.
The structural organization and staining properties of the dermis do not show any changes in different stages of the cycle.
The dermis is divided into the stratum laxum and the stratum compactum. Acid mucopolysaccharide deposits in the stratum laxum, which possibly bind water, may be involved in prevention of desiccation.
The numerous elastin fibres in the hinge regions are related to the greater elasticity of the skin in these sites.     

How the Statistics of Sequential Presentation Influence the Learning of Structure

Recent work has shown that humans can learn or detect complex dependencies among variables. Even learning a simple dependency involves the identification of an underlying model and the learning of its parameters. This process represents learning a structured problem. We are interested in an empirical assessment of some of the factors that enable humans to learn such a dependency over time. More specifically, we look at how the statistics of the presentation of samples from a given structure influence learning. Participants engage in an experimental task where they are required to predict the timing of a target. At the outset, they are oblivious to the existence of a relationship between the position of a stimulus and the required temporal response to intercept it. Different groups of participants are either presented with a Random Walk where consecutive stimuli were correlated or with stimuli that were uncorrelated over time. We find that the structural relationship implicit in the task is only learned in the conditions where the stimuli are independently drawn. This leads us to believe that humans require rich and independent sampling to learn hidden structures among variables.