Leptomonas wallacei shows distinct morphology and surface carbohydrates composition along the intestinal tract of its host Oncopeltus fasciatus (Hemiptera: Lygaeidae) and in axenic culture

Leptomonas wallacei is a monoxenic trypanosomatid that colonizes the digestive tract of the phytophagous hemipteran Oncopeltus fasciatus. This infection was specific and took place exclusively in midgut intestinal ventricles V3 and V4, and in the hindgut. Abundances of parasites in the hindgut were 54% less than those in the hindgut. Parasites in the hindgut were more slender and had a longer flagellum than those from the hindgut, which were rounded, with a shorter flagellum. Moreover, hindgut forms expressed sugar residues on the cell surface, recognized by the lectins from Griffonia simplicifolia-I (alpha-galactose, alpha-N-acetyl-galactosamine) and Helix pomatia (N-acetyl-galactosamine); those sugar residues were not present in protozoa from the midgut. In culture, parasites were morphologically similar to midgut forms, but differed from them because they did not express sugar residues that bind to lectin (beta-galactose(1-3) N-acetyl-galactosamine) from Arachis hypogaea.     

The role of temperature in determining distributions and coexistence of three species of Plestiodon

The Common Five-Lined Skink (Plestiodon fasciatus), Southeastern Five-Lined Skink (P. inexpectatus), and Broadheaded Skink (P. laticeps) are all found in forested ecosystems of the southeastern United States and occur in apparent sympatry. No aspect of their ecology has been quantitatively shown to be different. Differences in their natural history, such as northern extent of geographic range, observations of differences in habitat preference, and differing physiological responses to temperature, implicate the thermal environment as a potential niche dimension by which these organisms partition resources. Here we show that the northernmost extent of each species' range can be adequately discriminated by temperature extremes and that their preferred habitats differ in canopy cover, mean temperature, and daily maximum temperatures. These differences are supported by observations in the field. Based upon these findings and observations, we conclude that these species may be able to exist in such close proximity due to differences in their thermal niche, particularly the two like-sized species, P. fasciatus and P. inexpectatus. P. laticeps is a much larger lizard as an adult and functionally coexists with its congeners, potentially by partitioning resources along a different axis.     

条石鲷仔、稚、幼鱼脂肪酸组成变化研究

通过采用GC/MS法研究了条石鲷(Oplegnathus fasciatus)仔鱼、稚鱼及幼鱼阶段的脂肪酸组成和变化特点。共检测到28种脂肪酸,其中饱和脂肪酸(SFA)13种,单不饱和脂肪酸(MUFA)7种,多不饱和脂肪酸(PUFA)8种。结果表明:条石鲷鱼苗内源性营养阶段以饱和脂肪酸C16∶0、C20∶0及单不饱和脂肪酸C16∶1、C18∶1作为能量代谢的主要来源;必需脂肪酸C20∶4(n-6)(AA)、C22∶5(n-3)(DPA)和C22∶6(n-3)(DHA)在稚鱼期含量较低,∑EPA+DHA仅为6.89%,认为是发生稚鱼"胀鳔病"的主要原因;仔鱼开口前体内的DHA和EPA是由母体卵黄提供的。     

Microsatellite loci from the five‐lined skink (Eumeces fasciatus)

The geographical range of the five‐lined skink is the most expansive of any eastern North American lizard, ranging from previously glaciated southern Canada southward to the Gulf of Mexico and from the Atlantic seaboard west to Texas and Minnesota. The most northerly populations occur in southern Ontario and are of conservation concern. We developed six polymorphic dinucleotide microsatellite loci to examine the genetic structure within and among Ontario's populations and to examine the intrapopulation levels of genetic diversity relative to more southern populations.     

Effects of wing-pad removal and corpus allatum implantation on development of wings, flight muscles, and related structures in the striped ground cricket, Allonemobius fasciatus

ABSTRACT. Removal of a hindwing pad from late instar nymphs of the striped ground cricket, Allonemobius fasciatus DeGeer (Gryllidae) inhibits the formation of long-winged adults. All nymphs become short-winged when their hindwing pad is removed during the sixth (penultimate) instar or during the first 2 days of the seventh instar. When a hindwing pad is removed on day 4 of the seventh instar or later, there is no effect on wing development and at least 50% of the crickets emerge as long-winged adults as in controls.
The period sensitive for removal of a hindwing pad varies among different structures, e.g. elytra, hindwings, flight muscles, and the acrotergite of the first abdominal segment. As a result, some intermediate forms are produced when a hindwing pad is removed in the middle of the seventh instar.
Implantation of corpora allata (CA) into late instar nymphs also inhibits formation of long-winged adults. When CA are implanted on day 2 or 3 of the seventh instar, some of the resulting adults have abnormally short elytra. Implantation of CA at an earlier stage produces supernumerary (eighth instar) nymphs.     

Gene duplications circumvent trade‐offs in enzyme function: Insect adaptation to toxic host plants

Herbivorous insects and their adaptations against plant toxins provide striking opportunities to investigate the genetic basis of traits involved in coevolutionary interactions. Target site insensitivity to cardenolides has evolved convergently across six orders of insects, involving identical substitutions in the Na,K‐ATPase gene and repeated convergent gene duplications. The large milkweed bug, Oncopeltus fasciatus, has three copies of the Na,K‐ATPase α‐subunit gene that bear differing numbers of amino acid substitutions in the binding pocket for cardenolides. To analyze the effect of these substitutions on cardenolide resistance and to infer possible trade‐offs in gene function, we expressed the cardenolide‐sensitive Na,K‐ATPase of Drosophila melanogaster in vitro and introduced four distinct combinations of substitutions observed in the three gene copies of O. fasciatus. With an increasing number of substitutions, the sensitivity of the Na,K‐ATPase to a standard cardenolide decreased in a stepwise manner. At the same time, the enzyme's overall activity decreased significantly with increasing cardenolide resistance and only the least substituted mimic of the Na,K‐ATPase α1C copy maintained activity similar to the wild‐type enzyme. Our results suggest that the Na,K‐ATPase copies in O. fasciatus have diverged in function, enabling specific adaptations to dietary cardenolides while maintaining the functionality of this critical ion carrier.     

Breeding strategy of Acrossocheilus fasciatus in the Puxi Stream of the Huangshan Mountain

Breeding strategies of Acrossocheilus fasciatus were studied from 592 specimens collected monthly during May 2007 and April 2008 in the Puxi Stream of the Huangshan Mountain.Sex ratio of the studied population was 0.90∶1(♀∶♂),not significantly different from 1∶1.Both sexes reached their first sexual maturity at age 2(the second calendar year of their birth).Fifty percent of females and males reached maturity at a total length of 69.75 mm and 69.36 mm respectively,and the minimum total length was 61.54 mm an...     

乳草长蝽Ubx基因克隆及多转录本分析

针对非完全变态类昆虫发育关键基因的研究相对匮乏, 尤其缺少Hox基因家族的基因结构和序列信息。为了研究Hox基因家族成员之一的Ubx基因在非完全变态类昆虫中的结构特点, 本实验选取乳草长蝽Oncopeltus fasciatus (Dallas, 1852)为代表, 应用RACE和RT-PCR技术, 对其Ubx基因的全长开放阅读框进行克隆。结果显示: 乳草长蝽Ubx基因（Of-Ubx）开放阅读框全长888 bp, 推测的完整蛋白含有295个氨基酸。Southern blot证实Ubx基因以单拷贝形式存在且含有内含子。在Of-Ubx的YPWM基序和同源异型结构域之间存在选择性剪接位点, 可产生3种不同转录本。分析以上实验结果, 发现乳草长蝽与黑腹果蝇Drosophila melanogaster (Meigen, 1830)的Ubx基因拥有相似的剪接位置、剪接体组合和边界序列, 提示它们很可能具有相似的剪接机理。这是Ubx基因的多转录本现象在昆虫纲中果蝇属以外类群中的首次详尽报道。
     

Quick methods for evaluating survival of age-characterizable long-lived territorial birds

Survival is a key life-history trait in animals. However, most methods of survival estimation require substantial human and economic investment in the long term, particularly in species occurring in low densities, the case of most endangered species. An alternative to traditional recapture (CR) methods is estimation of adult survival based indirectly on either age ratios (AGR) or turnover rates (TOR) in territorial species. These 2 methods are applicable to bird species in which recruited individuals enter into the breeding population whilst still exhibiting the external traits that distinguish those animals from experienced adults. The main advantages of these methods are that survival can be easily estimated for all monitored individuals after just 1 or 2 breeding seasons and that disturbance to the species is minimized. The main constraints of indirect methods are that the assumptions are more restrictive than in CR methods, and survival estimates, although comparable between sites and years, may be biased. We used data from a long-term monitoring survey of 2 populations of the endangered Bonelli's eagle (Aquila fasciata), one in Catalonia (NE Spain) and the other in Provence and Languedoc-Roussillon (SE France). We evaluated survival estimates using the AGR and TOR methods and compared them with CR methods and provide suitable corrections for refining survival estimates based on indirect methods. In Catalonia (2002–2008), survival was estimated at 0.84 by CR methods (SE = 0.047; n = 25 radio tagged eagles), at 0.86 by the corrected AGR method (SE = 0.011; n = 558 bird * year), and at 0.86 by the corrected TOR method (SE = 0.022; n = 547 bird * year). In France (1999–2008), survival was estimated at 0.88 by CR methods (SE = 0.040; n = 45 darvic banded eagles), at 0.87 by the corrected AGR method (SE = 0.015; n = 443 bird * year), and at 0.87 by the corrected TOR method (SE = 0.015; n = 438 bird * year). All analyses suggest that females survive better than males and that individuals from the French population survive better than individuals from the Catalan population. We conclude that indirect methods, which should not be regarded as a substitute of CR methods, will allow wildlife managers and researchers to estimate accurately adult survival in a territorial species over a short period of time and to monitor survival across populations over large geographic ranges and over time. © 2011 The Wildlife Society.