Maternal predator‐exposure affects offspring size at birth but not telomere length in a live‐bearing fish

The perception of predation risk could affect prey phenotype both within and between generations (via parental effects). The response to predation risk could involve modifications in physiology, morphology, and behavior and can ultimately affect long‐term fitness. Among the possible modifications mediated by the exposure to predation risk, telomere length could be a proxy for investigating the response to predation risk both within and between generations, as telomeres can be significantly affected by environmental stress. Maternal exposure to the perception of predation risk can affect a variety of offspring traits but the effect on offspring telomere length has never been experimentally tested. Using a live‐bearing fish, the guppy (Poecilia reticulata), we tested if the perceived risk of predation could affect the telomere length of adult females directly and that of their offspring with a balanced experimental setup that allowed us to control for both maternal and paternal contribution. We exposed female guppies to the perception of predation risk during gestation using a combination of both visual and chemical cues and we then measured female telomere length after the exposure period. Maternal effects mediated by the exposure to predation risk were measured on offspring telomere length and body size at birth. Contrary to our predictions, we did not find a significant effect of predation‐exposure neither on female nor on offspring telomere length, but females exposed to predation risk produced smaller offspring at birth. We discuss the possible explanations for our findings and advocate for further research on telomere dynamics in ectotherms.     

Evidence for male-biased effective sex ratio and recent step-by-step colonization in the bivalve Pinctada mazatlanica

This paper presents a comparison of the geographical distribution of genetic variability at mitochondrial and nuclear loci among pearl oyster populations from the tropical American Pacific coast (Pinctada mazatlanica). Surprisingly, both mitochondrial and nuclear gene variability decreased regularly from north to south of the studied area, which, altogether with a significant correlation between genetic and geographical distances for mtDNA, suggests a recent colonization or re-colonization of the southern areas. However, the loss of diversity between north and south was much more important for mitochondrial than for nuclear DNA, and this did not translate into measurable fixation index at nuclear loci (theta = 0.03, n.s.), contrary to the mitochondrial data (theta = 0.18*). Smaller effective size of mtDNA accentuated by a strong male-biased effective sex ratio and step-by-step colonization from northern areas can explain this discrepancy among natural populations of this protandric species.     

A plant Kunitz-type inhibitor mimics bradykinin-induced cytosolic calcium increase and intestinal smooth muscle contraction

Abstract: BbKI is a kallikrein inhibitor with a reactive site sequence similar to that of kinins, the vasoactive peptides inserted in kininogen moieties. This structural similarity probably contributes to the strong interaction with plasma kallikrein, the enzyme that releases, from high-molecular weight kininogen (HMWK), the proinflammatory peptide bradykinin, which acts on B2 receptors (B2R). BbKI was examined on smooth muscle contraction and Ca2+ mobilization, in which the kallikrein-kinin system is involved. Contrary to expectations, BbKI (1.8 μm) increased [Ca2+]cand contraction, as observed with BK (2.0 μm). Not blocked by B1 receptors (B1R), the BbKI agonistic effect was blocked by the B2R antagonist, HOE-140 (6 μm), and the involvement of B2R was confirmed in B2R-knockout mice intestine. The same tissue response was obtained using a synthetic peptide derived from the BbKI reactive site structure, more resistant than BK to angiotensin I-converting enzyme (ACE) hydrolysis. Depending on the concentration, BbKI has a dual effect. At a low concentration, BbKI acts as a potent kallikrein inhibitor; however, due to the similarity to BK, in high concentrations, BbKI greatly increases Ca2+ release from internal storages, as a consequence of its interaction with B2R. Therefore, the antagonistic and agonistic effects of BbKI may be considered in conditions of B2R involvement.     

Dimorphic expression of uncoupling protein-3 in golden hamster harderian gland: effects of castration and testosterone administration

Hamster (Mesocricetus auratus) harderian gland (HG) is a dimorphic orbital gland producing a copious lipid secretion. Two cell-types are present in hamster HG, type I in both sexes, type II only in males. In hamster HGs, we found a marked sexual dichotomy in the expression of uncoupling protein-3 (UCP3), a mitochondrial protein carrier, that probably exports fatty acid anions and fatty acid peroxides from the mitochondrial matrix. Following castration and/or testosterone treatment: (1) UCP3 levels correlated with the type II-cell percentage, not with testosterone levels, (2) in male HGs, UCP3 was comparable to female levels at 30 days post-castration (when the type II-cell percentage had fallen from 50 to 5%), although testosterone was already near zero at 15 days (when neither the type II-cell percentage nor the UCP3 level had fallen), and testosterone-replacement therapy prevented these changes. Testosterone-treated females possessed type II cells and a UCP3 level about twofold higher than in control females. Males displayed more intense UCP3 immunohistochemical positivity in type I HG cells than females. Hence, testosterone may indirectly control UCP3 expression by regulating the gland's morphological and lipid dimorphism. Straight-chain fatty acids [found in alkyl diacylglycerols (ADGs) in males] are oxidized predominantly in mitochondria, branched-chain fatty acids (abundant in ADGs in females) predominantly in peroxisomes, so we speculate that the higher UCP3 expression in males reflects greater fatty acid flux in HG mitochondria. This is supported by our finding that in female (not male) HGs, the peroxisome-rich fraction contained alpha-methylacyl-CoA racemase (AMACR), an enzyme important in the beta-oxidation of branched-chain fatty acids.     

<Emphasis Type="SmallCaps">d</Emphasis>-Aspartate affects secretory activity in rat Harderian gland: molecular mechanism and functional significance

In this paper, the role of d-aspartate in the rat Harderian gland (HG) was investigated by histochemical, ultrastructural, and biochemical analyses. In this gland, substantial amounts of endogenous d-Asp were detected, along with aspartate racemases that convert d-Asp to l-Asp and vice versa. We found that the gland was capable of uptaking and accumulating exogenously administered d-Asp. d-Asp acute treatment markedly increased lipid and porphyrin secretion and induced a powerful hyperaemia in inter-acinar interstitial tissue. Since d-Asp is known to be recognized by NMDA receptors, the expression of such receptors in rat HG led us to the hypothesis that d-Asp acute treatment induced the activation of the extracellular signal-regulated protein kinase (ERK) and nitric oxide synthase (NOS) pathways mediated by NMDA. Interestingly, as a result of enhanced oxidative stress due to increased porphyrin secretion, the revealed activation of the stress-activated protein kinase/c-jun N-terminal kinase (SAPK/JNK) pro-apoptotic pathway was probably triggered by the gland itself to preserve its cellular integrity.     

On the first record of a potentially harmful fish, Sparus aurata in the Gulf of California

The record of free and healthy Mediterranean gilt-head seabream Sparus aurata Linnaeus, 1758 in waters of the Gulf of California, México is documented for the first time. Consequences of this introduction are briefly outlined.     

Experimental evaluation of the relationship between lethal or non-lethal virulence and transmission success in malaria parasite infections

Background

Theoretical studies suggest that direct and indirect selection have the potential to cause substantial evolutionary change in female mate choice. Similarly, sexual selection is considered a strong force in the evolution of male attractiveness and the exaggeration of secondary sexual traits. Few studies have, however, directly tested how female mate choice and male attractiveness respond to selection. Here we report the results of a selection experiment in which we selected directly on female mating preference for attractive males and, independently, on male attractiveness in the guppy, Poecilia reticulata. We measured the direct and correlated responses of female mate choice and male attractiveness to selection and the correlated responses of male ornamental traits, female fecundity and adult male and female survival.

Results

Surprisingly, neither female mate choice nor male attractiveness responded significantly to direct or to indirect selection. Fecundity did differ significantly among lines in a way that suggests a possible sexually-antagonistic cost to male attractiveness.

Conclusions

The opportunity for evolutionary change in female mate choice and male attractiveness may be much smaller than predicted by current theory, and may thus have important consequences for how we understand the evolution of female mate choice and male attractiveness. We discuss a number of factors that may have constrained the response of female choice and male attractiveness to selection, including low heritabilities, low levels of genetic (co)variation in the multivariate direction of selection, sexually-antagonistic constraint on sexual selection and the "environmental covariance hypothesis".

     

The Use of Bayesian Networks to Assess the Quality of Evidence from Research Synthesis: 2. Inter-Rater Reliability and Comparison with Standard GRADE Assessment

Background

The grades of recommendation, assessment, development and evaluation (GRADE) approach is widely implemented in systematic reviews, health technology assessment and guideline development organisations throughout the world. We have previously reported on the development of the Semi-Automated Quality Assessment Tool (SAQAT), which enables a semi-automated validity assessment based on GRADE criteria. The main advantage to our approach is the potential to improve inter-rater agreement of GRADE assessments particularly when used by less experienced researchers, because such judgements can be complex and challenging to apply without training. This is the first study examining the inter-rater agreement of the SAQAT.

Methods

We conducted two studies to compare: a) the inter-rater agreement of two researchers using the SAQAT independently on 28 meta-analyses and b) the inter-rater agreement between a researcher using the SAQAT (who had no experience of using GRADE) and an experienced member of the GRADE working group conducting a standard GRADE assessment on 15 meta-analyses.

Results

There was substantial agreement between independent researchers using the Quality Assessment Tool for all domains (for example, overall GRADE rating: weighted kappa 0.79; 95% CI 0.65 to 0.93). Comparison between the SAQAT and a standard GRADE assessment suggested that inconsistency was parameterised too conservatively by the SAQAT. Therefore the tool was amended. Following amendment we found fair-to-moderate agreement between the standard GRADE assessment and the SAQAT (for example, overall GRADE rating: weighted kappa 0.35; 95% CI 0.09 to 0.87).

Conclusions

Despite a need for further research, the SAQAT may aid consistent application of GRADE, particularly by less experienced researchers.