The evolution of molluscs

Molluscs are extremely diverse invertebrate animals with a rich fossil record, highly divergent life cycles, and considerable economical and ecological importance. Key representatives include worm‐like aplacophorans, armoured groups (e.g. polyplacophorans, gastropods, bivalves) and the highly complex cephalopods. Molluscan origins and evolution of their different phenotypes have largely remained unresolved, but significant progress has been made over recent years. Phylogenomic studies revealed a dichotomy of the phylum, resulting in Aculifera (shell‐less aplacophorans and multi‐shelled polyplacophorans) and Conchifera (all other, primarily uni‐shelled groups). This challenged traditional hypotheses that proposed that molluscs gradually evolved complex phenotypes from simple, worm‐like animals, a view that is corroborated by developmental studies that showed that aplacophorans are secondarily simplified. Gene expression data indicate that key regulators involved in anterior–posterior patterning (the homeobox‐containing Hox genes) lost this function and were co‐opted into the evolution of taxon‐specific novelties in conchiferans. While the bone morphogenetic protein (BMP)/decapentaplegic (Dpp) signalling pathway, that mediates dorso‐ventral axis formation, and molecular components that establish chirality appear to be more conserved between molluscs and other metazoans, variations from the common scheme occur within molluscan sublineages. The deviation of various molluscs from developmental pathways that otherwise appear widely conserved among metazoans provides novel hypotheses on molluscan evolution that can be tested with genome editing tools such as the CRISPR/Cas9 (clustered regularly interspaced short palindromic repeats/clustered regularly interspaced short palindromic repeats‐associated protein9) system.     

Treatment with CRH-1 antagonist antalarmin reduces behavioral and endocrine responses to social stressors in marmosets (Callithrix kuhlii)

Corticotropin-releasing hormone (CRH) has multiple roles in coordinating the behavioral and endocrine responses to a host of environmental challenges, including social stressors. In the present study we evaluated the role of CRH in mediating responses to a moderate social stressor in Wied's black tufted-eared marmosets (Callithrix kuhlii). Male and female marmosets (n=14) were administered antalarmin (a selective CRH-1 receptor antagonist; 50 microg/kg, p.o.) or vehicle in a blind, counterbalanced, crossover design. One hr after treatment, marmosets were separated from long-term pairmates and then housed alone in a novel enclosure for 7 hr. Behavior was recorded during separation and upon reunion with the partner, and urine samples for cortisol assay collected before, during, and after the intervention. Separation from partners elevated urinary cortisol concentrations over baseline for both conditions, but antalarmin treatment reduced the magnitude of the elevation. Antalarmin also lowered rates of behavioral patterns associated with arousal (alarm and "e-e" vocalizations, object manipulate/chew), but had no effect on contact calls, locomotory activity or alertness. Although most patterns of social behavior upon reunion with the partner were not affected by antalarmin, antalarmin-treated marmosets displayed more sexual behavior (mounts and copulations) upon reunion. These data indicate that antagonism of the CRH-1 receptor acts to reduce the magnitude of both endocrine and behavioral responses to a moderate social stressor without causing any overall reduction in alertness or general activity. This supports the hypothesis that CRH, acting through its type 1 receptor, is involved in coordinating the responses to anxiety-producing events. These results further suggest that the marmoset is a useful model for exploration of the role of CRH in mediating the behavioral and neuroendocrine responses to psychosocial stressors, particularly in the context of heterosexual social relationships.     

Non-crystallographic symmetry of crystal of neutral phospholipase A2 from Agkistrodon halys Pallas

Agkistrodotoxin, a neutral phospholipase A₂ with high presynaptic neurotoxicity from the venom of Agkistrodon halys Pallas, has been crystallized by hanging drop vapor diffusion method. The crystal belongs to P2₁ space group with the cell dimensions a = 10.836 nm, b=8.486nm, c = 7.082nm, β=109.87$ showing C2 pseu-do-symmetry. Diffraction data to 0. 26 nm resolution have been collected on a Siemens X-200B area detector. C2 pseu-do-symmetry suggests that there exists a non-crystallographic two-fold axis parallel to crystallographic b axis. Self-rotation function calculation with different integrated radius and resolution ranges using the program POLARRFN yields four stable high peaks corresponding to three more non-crystallographic two-fold axis and one special non-crystal-lographic symmetry. The molecules in the asymmetric unit are suggested to be arranged in a manner of "dimer of dimers" by inference.     

The role of estradiol in adrenal insufficiency and its interaction with corticosterone on hydromineral balance

Estradiol (E2) plays an important role in controlling the homeostasis of body fluids. Several studies have reported the involvement of the hypothalamic pituitary adrenal axis (HPA) in the homeostatic control of hydromineral balance and the influence of estrogens on the modulation of this system. Nevertheless, until now, the physiological relevance of HPA axis activity on the hydromineral balance in females has not yet been fully elucidated. Therefore, the objective of the present study was to evaluate the effects of E2 (20 μg/animal) pretreatment on neuroendocrine and hydroelectrolyte changes induced by adrenalectomy (ADX) with or without glucocorticoid hormone replacement (corticosterone, CORT; 10 mg/kg) in ovariectomized rats (OVX). The results show that sodium appetite, natriuresis and the elevated plasma angiotensin II (ANG II) concentration induced by ADX were attenuated by E2 pretreatment. Additionally, a reduction of AT1 mRNA expression in the subfornical organ (SFO) and an increase in plasma atrial natriuretic peptide (ANP) concentrations by E2 pretreatment were observed. E2 pretreatment reversed the reduction in water intake induced by ADX in ADX CORT-replaced rats. Moreover, E2 pretreatment attenuated corticotropin releasing factor (CRF) mRNA expression in the paraventricular nucleus (PVN) induced by ADX. In contrast, E2 pretreatment increased CRF mRNA expression in the PVN in ADX CORT-replaced rats. Taken together, these results suggest that E2 has an important role in the modulation of behavioral and neuroendocrine responses involved in the maintenance of body fluid homeostasis in ADX rats with or without glucocorticoid replacement therapy.     

Immunosuppression induced by central action of morphine is not blocked by mifepristone (RU 486)

Morphine causes immunosuppression by binding to opioid receptors on immune cells, or indirectly by acting on receptors in the brain. However, morphine exact mechanism of action has not been elucidated. In the present study, we investigated the role of glucocorticoids in morphine-mediated immunosuppression after acute action in the rat mesencephalon periaqueductal gray (PAG). Natural killer (NK) cell activity and T cell proliferation were used to evaluate potential indirect mechanisms of morphine action. Microinjection of morphine in the ventral-caudal aspect of the PAG significantly (p < 0.01) suppressed splenic NK cell cytotoxic activity (32% reduction), and antiTCR-, IL-2-, antiTCR + IL-2, and Con A-induced thymic (30% to 50% reduction) and splenic (35% to 70% reduction) lymphocyte proliferation compared with PAG-injected saline control animals. The glucocorticoid receptor antagonist mifepristone (RU 486) did not block the immunosuppressive effects of morphine, suggesting that such effects are independent of activation of the hypothalamic-pituitary-adrenal axis.