Female polymorphism, condition differences, and variation in male harassment and ambient temperature

Female polymorphism is considered to be maintained through negative frequency-dependent selection imposed by costly male harassment. However, few studies have questioned whether male harassment negatively affects female morph success and does so differently for female morphs, especially in the wild. In the present study, we quantified female morph condition (relative body mass and energy reserves) for a colour polymorphic damselfly under natural conditions and evaluated these measures against variation in proxies of male harassment (population density and operational sex ratio) and ambient temperature. Differences in protein content between female morphs were detected and the variation in condition could partly be explained from concomitant variation in proxies of male harassment. Specifically, the relationship between protein content and operational sex ratio differed between morphs in that the negative effect of male harassment was more pronounced in gynomorphs than in andromorphs. In addition, ambient temperature affected the body mass and protein content of female morphs differently, with andromorphs having higher condition values in favourable weather conditions, whereas, for gynomorphs, the patterns tended to be opposite. In conclusion, the results obtained in the present study suggest that male harassment negatively and differentially affects female morph success. Future studies should aim to elucidate whether the observed effects of ambient temperature contribute to the maintenance of the polymorphism.  © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 97 , 545–554.     

A study of the diversity and geographical variation in numbers of leg‐bearing segments in centipedes (Chilopoda: Geophilomorpha) in north‐western Europe

Five species of geophilomorphs, Strigamia maritima (Leach, 1817), Geophilus flavus (De Geer, 1778), Geophilus truncorum Bergsøe and Meinert, 1866, Geophilus proximus C. L. Koch, 1847, and Pachymerium ferrugineum (C. L. Koch, 1835), from various sample sites in north‐western Europe were examined for numbers of leg‐bearing segments. Where data was adequate, mean segment numbers were correlated with latitudinal gradients for each species. Solely in S. maritima and some populations of P. ferrugineum did the results show a highly significant geographic pattern towards more leg‐bearing segments in southern populations of both sexes. As concerns G. proximus, we presented for the first time a remarkable geographic shift towards an increased number of pairs of legs in northern populations. Contrary to the conventional geographic pattern, we found that G. flavus and G. truncorum did not exhibit a north–south increase or decrease in segment number. Although there was no general/universal evidence supporting the occurrence of a significant regression slope between mean segment number and latitude/temperature, more information shows that the overall region‐to‐region segment variation was highly significant in both sexes. In S. maritima and P. ferrugineum mean segment number was correlated with the north–south temperature cline. The same was not observed in G. proximus. Parthenogenesis in G. proximus, and a series of ecological characteristics such as habitat preferences, spatial distribution, and fragmented populations could explain the presence or absence of a geographic patterning of segment number variation along a latitudinal cline. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 100 , 899–909.     

The effect of sugar meals and body size on fecundity and longevity of female Aedes communis(Diptera: Culicidae)

Abstract. Starved females of Aedes communis (DeGeer) had significantly shorter mean lifespans than females with access to one blood meal and/or sugar meals. For the starving females, lifespan was significantly correlated with wing length. This correlation was not found in sugar- and/or blood-fed females. Fructose and sucrose had similar effects on mosquito lifespan. The 25% and 50% (w/w) solutions of each, increased mean lifespans to 37.8 ± 7.2 and 34.9 ± 9.1 days, respectively. A 10% solution, of either sugar, was significantly inferior, mean lifespan 23.2 ± 10.2 days. The initial sugar meal was very important for female longevity. Subsequent meals aided in ovarian development. One sugar meal, one blood meal, and several sugar meals during oogenesis was found to be the optimal diet for the female mosquitoes in this study.     

Antigenic Analysis of Virulent and Avirulent Strains of Trichomonas gallinae by Gel Diffusion Methods*

SYNOPSIS. Antigenic constitution of 5 Trichomonas gallinae strains and substrains was analyzed by gel diffusion technics. Fresh isolates of the very virulent JB and of an avirulent SG strain as well as avirulent substrains JBC and SGC, derived from JB and SG respectively by prolonged in vitro cultivation, were used in the experiments. An originally avirulent AG strain that was attenuated still further and lost its infectivity for pigeons during many years of serial transfers in nonliving media also was analyzed. Two major groups of antigens, A and B, were differentiated on the basis of precipitin line patterns formed in gel diffusion reactions involving the 5 strains and substrains and antisera prepared in rabbits against each of these trichomonad stocks. Group A was subdivided further into subgroups [A] and (A). JB, JBC, AG, and SGC trichomonads appeared to share all or nearly all antigens of both these subgroups, but AG strain contained some unique [A] and (A) antigens in addition to those which it had in common with the remaining 4 strains and substrains. Group B antigens were divided into 5 subgroups, B₁ to B₅. The complete B₁ antigenic complex was found in JB and JBC trichomonads and part of this complex was present also in SG strain and SGC substrain. In all instances, subgroup B₁ antigens stimulated production of specific antibodies in rabbits and combined with these antibodies present in immune sera. The complete B₂ antigenic complex was found only in JBC substrain. Some subgroup B₂ antigens were present also in JB trichomonads. Very few of these, however, were capable of stimulating antibody production in rabbits. The more numerous B₂ elements of JB strain that did not stimulate immunologic responses in rabbits, might be in the form of incomplete hapten-like antigens. All subgroup B₂ antigens found in JB strain represented only a portion of the B₂ complex associated with JBC substrain. Subgroup B₂ was characteristic of SG and SGC trichomonads, the latter substrain differing from the parental SG strain in the levels of both B₂ and B₁ antigens; these differences, however, were purely quantitative. JB strain reacted with some of subgroup B₃ antibodies present in SG and SGC antisera, but failed to stimulate antibody formation against any of these antigens in rabbits. The B₃ elements of JB trichomonads might be incomplete antigens. AG strain was characterized by having B₄ and B₅ antigenic complexes. The very small part of subgroup B₄, represented by a weak precipitin line in reactions between JB strain or JBC substrain and anti-AG serum, suggested the presence of some incomplete B₄ antigens in these trichomonads. Irrespective of whether freshly isolated avirulent strains or substrains attenuated by prolonged in vitro cultivation are examined by gel diffusion, such organisms are found richer in subgroup B antigens than the fully virulent JB trichomonads. All the results suggest that there may be a direct relationship between antigenic constitution and virulence of T. gallinae strains.     

Protein Targeting into Secondary Plastids1

ABSTRACT. Most of the coding capacity of primary plastids is reserved for expressing some central components of the photosynthesis machinery and the translation apparatus. Thus, for the bulk of biochemical and cell biological reactions performed within the primary plastids, many nucleus‐encoded components have to be transported posttranslationally into the organelle. The same is true for plastids surrounded by more than two membranes, where additional cellular compartments have to be supplied with nucleus‐encoded proteins, leading to a corresponding increase in complexity of topogenic signals, transport and sorting machineries. In this review, we summarize recent progress in elucidating protein transport across up to five plastid membranes in plastids evolved in secondary endosymbiosis. Current data indicate that the mechanisms for protein transport across multiple membranes have evolved by altering pre‐existing ones to new requirements in secondary plastids.     

Amino-Terminal Processing of the Human Cannabinoid Receptor 1

The human cannabinoid receptor 1 (CB1), a G protein-coupled receptor (GPCR), translocates its long amino-terminal (N-terminal) domain across the endoplasmic reticulum (ER) membrane in a C-to-N terminal direction. Using the Semliki Forest virus (SFV) expression system, CB1 was expressed in baby hamster kidney (BHK) cells. It was found that a large fraction of the CB1 molecules were N-terminally truncated prior to ER translocation. Truncation was fast and independent of the proteasome. It is concluded that the truncation process might be a way to create a novel type of CB1.