Antimicrobial activity of the Naja atra cathelicidin and related small peptides

We have identified an 11-residue pattern (KR(F/A)KKFFKK(L/P)K), which we have named the ATRA motif, within the sequence of the Chinese cobra (Naja atra) cathelicidin. A series of 11-residue peptides (ATRA-1, -2, -1A and -1P) were designed to probe the significance of the conserved residues within the ATRA motif, and their contributions to antimicrobial performance. The antimicrobial activities of the peptides were assessed against Escherichia coli K12 strain and Aggregatibacter actinomycetemcomitans Y4. ATRA-1 and -1A, demonstrated potencies comparable to that of N. atra cathelicidin. Structural examination by circular dichroism of the four short peptides suggested the significance of specific amino acid positions within the motif by their contribution to helicity. The results of these studies indicate that short peptides derived from the repeated ATRA motif from the N. atra cathelicidin can demonstrate both low toxicity against host cells and high antimicrobial activity against the gram-negative bacteria used in this study. They constitute novel, effective antimicrobial peptides that are much shorter (and thus less expensive to produce) than the natural cathelicidins, and they may represent new templates for therapeutic drug development.     

The influence of population density on fission and growth of Holothuria atra in natural mesocosms

Investigation of the population dynamics, asexual reproduction (fission) and growth of holothuroids has been impeded by the difficulty of tagging individuals. We conducted the first tests on the interactions between population density, fission and growth of holothuroids in experimental populations placed in natural mesocosms (microatolls) at One Tree Reef (OTR), Great Barrier Reef. Similarly sized Holothuria atra were translocated to the microatolls in low (LDT) and high (HDT) density treatments. We hypothesised that holothuroids in lower density treatments would have more resources per individual and that this would promote higher frequencies of asexual reproduction and smaller individuals. The seasonal pattern of fission was similar in natural (unmanipulated) and experimental populations, with the maximum number of fission products occurring in winter and spring. The overall density of the LDT (0.19 ind. m^- 2) and HDT (0.59 ind. m^- 2) did not vary over time. This ‘steady state’ suggested that some fission products died and that asexual reproduction compensated for overall mortality and emigration. There was no difference in sediment chlorophyll pigments between treatments indicating that the different densities of H. atra did not affect benthic microalgal biomass. The percentage of fission products was greater in the LDT than the HDT but this difference was not statistically significant, providing some support for the hypothesis that H. atra in the LDT exhibit a higher fission rates. At the end of the experiment H. atra in LDT were significantly longer and heavier than in HDT. H. atra surpassed their initial deployment weight and length after 13 months in the LDT by 115.2% and 45.2% respectively and in the HDT 86.9% and 24.6% respectively, changing from the small to the large phenotype known for this species. This differential growth may be linked to habitat stability and high benthic productivity and demonstrates the phenotypic plasticity of holothuroids and potential to achieve ‘Optimum Individual Size’ with respect to environmental conditions. Our results will assist in finetuning conceptual models on asexual reproduction and future experimental studies on the phenomena of fission and plastic growth in holothuroids.     

骨顶鸡的种内巢寄生现象及其抵御机制初探

在2008～ 2009年2个繁殖季节对黑龙江省安邦河湿地自然保护区和大庆龙凤湿地自然保护区的骨顶鸡( Fulica atra)种群进行了调查.结果发现,骨顶鸡具有很高比例的种内巢寄生现象,平均巢寄生比例达38.55％;且发现骨顶鸡具有类似于同属的美洲骨顶鸡(F.americana)的拒卵方式,主要包括埋卵、逐出和啄破....     

Influence of sex and genetic background on anxiety-related and stress-induced behaviour of prodynorphin-deficient mice

The role of dynorphin/kappa opioid receptors in epilepsy and addiction are well accepted, but their function in emotional control is not yet fully understood. Data obtained from different strains of prodynorphin (Pdyn)- and kappa opioid receptor (KOP)-deficient mice do not provide a consistent picture of the functions of Dyn/KOP in anxiety, suggesting the influence of testing conditions and/or genetic background. Therefore, we investigated the behaviour and neurochemistry of male and female Pdyn KO mice on the balb/c and C57Bl/6N background. Consistent with our results obtained from male mice on the C57bl/6N background, we observed a less anxious phenotype in the elevated plus maze, open-field and light-dark test in male mice on the balb/c background. Female mice on the balb/c background also displayed less anxiety like behaviour; however these data reflect high trait anxiety and inter-individual differences. In contrast, female mice on the C57Bl/6N background displayed low trait anxiety and a paradigm-dependent reduction of anxiety. No differences were observed in the forced swim test, while balb/c Pdyn KO mice displayed prolonged immobility in the tail suspension test. In line with our previous results, we observed reduced CRH mRNA in the central amygdala in all groups of mice. In contrast, the recently observed CRH mRNA reduction in the hypothalamic paraventricular nucleus appears restricted to male, but not female mice. Our data support previous data suggesting a pronounced impact of endogenous prodynorphin-derived peptides on anxiety. Moreover, our data support the idea that the less anxious phenotype manifests only at elevated stress levels.     

Landing-site selection and searching behaviour in the micro-lepidopteron Agonopteryx pulvipennella

The cryptic micro-lepidopteron Agonopteryx pulvipennella (Oecophoridae) camouflages itself against predators by distinguishing among several shades of grey and preferring landing sites that match the reflectance of its fore-wings. Variations in the time it spends searching out a site are of survival value: they increase the moth's chances of finding a good site and decrease predation risk on a poor site.     

The genetic structure of the A mating-type locus of Lentinula edodes

The Shiitake mushroom, Lentinula edodes (Berk.) Pegler is a tetrapolar basidiomycete with two unlinked mating-type loci, commonly called the A and B loci. Identifying the mating-types in shiitake is important for enhancing the breeding and cultivation of this economically-important edible mushroom. Here, we identified the A mating-type locus from the first draft genome sequence of L. edodes and characterized multiple alleles from different monokaryotic strains. Two intron-length polymorphism markers were developed to facilitate rapid molecular determination of A mating-type. L. edodes sequences were compared with those of known tetrapolar and bipolar basidiomycete species. The A mating-type genes are conserved at the homeodomain region across the order Agaricales. However, we observed unique genomic organization of the locus in L. edodes which exhibits atypical gene order and multiple repetitive elements around its A locus. To our knowledge, this is the first known exception among Homobasidiomycetes, in which the mitochondrial intermediate peptidase (mip) gene is not closely linked to A locus.     

Defensive behaviour and its inheritance in the anabantoid fish, Macropodus opercularis and Macropodus opercularis concolor

In this preliminary study defense behaviour patterns (fear responses) are described in two closely related, behaviourally different inbred labyrinth fish subspecies and in their F₁ generation. The subspecies M. opercularis (characterized briefly by “active escape”) and M. opercularis concolor (characterized by “passive escape”) showed specific differences in the manifestation of certain defense behaviour patterns. In the F₁ hybrid generation dominance and overdominance of M. opercularis was found in most defense behaviour patterns. Analysing the frequencies and sequences of movement patterns it could be shown that defensive behaviour is not a random or entirely “plastic” process but that there is sequential linkage between the patterns and they form characteristic clusters. Our results suggest that manifestations of different patterns are under genetic control and presumably, genetic determination of certain patterns is not very complex. Attempts were made to determine whole brain noradrenaline, serotonine and dopamine levels of the two subspecies and a significant difference was found in the noradrenaline content.     

Exploratory behaviour of goldfish Carassius auratus

The exploratory locomotor behaviour of twenty-one naïve goldfish in a homogeneous open field during 20-hr periods was monitored and analysed into spatial and temporal characteristics. The fish did not randomly explore the entire field. Locomotion is organized spatially and temporally. The fish moves about in one specific area during a specific time after which it displaces the centre of its activity to another area. The time spent in earch area is a function of rate of activity, expressed by a linear equation and, during the initial 4 hr, the elapsed time in the novel environment (novelty content). The area-by-area exploration was never replaced by random exploration throughout the environment during the 20-hr periods of observation.     

Chemical variation within and between individuals of the lichenized ascomycete Tephromela atra

HPLC-analysis was used to determine the concentrations of the lichen compounds alectoronic acid (depsidon), -collatolic acid (depsidon) and atranorin (depsid) in the lichenized ascomycete Tephromela atra (syn. Lecanon atra) (Hudson) Hafeliner from limestone walls on the Baltic island of Öland, Sweden. In 24 individuals of T. atra sampled on a stone wall, the pre-reproductive and reproductive tissue did not differ in the concentrations of alectoronic acid, collatolic acid and atranorin. The concentrations of the three lichen compounds were inter-correlated in the reproductive tissue, but not in the pre-reproductive tissue. Single individuals of T. atra ranged in area covered from 10.1 to 147.4 cm² (mean: 38.5 cm²; N=24); 38.6% of this area was pre-reproductive tissue. However, the concentrations of the three lichen compounds were correlated neither with the total area covered by the lichen nor with the percentage of pre-reproductive tissue. This suggests that the concentrations of the lichen compounds do not change with increasing size (age) of the lichen. Analysis of specimens of T. atra from eight localities revealed a significant variation in lichen compounds (range between localities: alectoronic acid 0.60–3.26 μg/mg lichen dry weight (DW); collatolic acid 2.14–11.59 μg/mg lichen DW; atranorin 0.58–4.16 μg/mg lichen DW). The level of grazing observed in the lichens differed significantly among localities. However, no correlations between the concentrations of the three lichen compounds and the grazing damage to the lichens were found.     

Mating behaviour in the Australian reptile tick Aponomma hydrosauri

Females of the Australian reptile tick Aponomma hydrosauri make few movements once they are attached to a host. Males move significantly more often on hosts with females attached. Male movement often leads to contact and courtship with females. Movement is most frequent in the early part of the dark phase of a photoperiod. After contact the courtship, both on the host and in experimentally induced off-host situations, follows a stereotyped sequence of positional orientations, here divided into six phases. Copulation does not automatically follow courtship initiation, and in particular successful courtship requires females to respond to male initiation by lifting their hind legs to allow the male to crawl under. Compared to other animal species, the males of A. hydrosauri play an unusually passive role in mate seeking. This may be explained by the extremely patchy distribution of the mate-finding environment, lizards.     

Genome-scale genetic engineering in Escherichia coli

Genome engineering has been developed to create useful strains for biological studies and industrial uses. However, a continuous challenge remained in the field: technical limitations in high-throughput screening and precise manipulation of strains. Today, technical improvements have made genome engineering more rapid and efficient. This review introduces recent advances in genome engineering technologies applied to Escherichia coli as well as multiplex automated genome engineering (MAGE), a recent technique proposed as a powerful toolkit due to its straightforward process, rapid experimental procedures, and highly efficient properties.     

The relationship between locomotor activity and sexual behaviour in ebony strains of Drosophila melanogaster

Male flies homozygous for the ebony¹¹ mutant allele suffer a severe visual impairment and consequently show poor mating success. However, ebony males show improved mating in darkness because they initiate courtship more quickly than in the light. They also exhibit a competitive superiority over wild-type males under darkened conditoons that correlates with the observed increase in the mutant's locomotor activity. Locomotor activity levels were subsequently shown to correlate with several indices of mating success under both dark and illuminated conditions. The evolutionary implications of this relationship between the two characters are discussed.     

基于28S, COI和Cytb基因序列的薜荔和爱玉子传粉小蜂分子遗传关系研究

薜荔和爱玉子均属于桑科榕属植物,二者为同一物种的原变种与变种的关系,早期研究认为这两种榕树与同一种传粉榕小蜂(Wiebesia pumilae (Hill))建立了稳定的互利共生关系,但近期在形态学、生态学、传粉生物学等方面对二者的研究结果表明,薜荔传粉小蜂和爱玉子传粉小蜂之间可能发生了遗传分化。实验用核糖体28SrDNAD1-D3区、线粒体Cytb及COI基因部分序列,对采自福建3个不同样地的薜荔传粉小蜂和3个不同品系的栽培爱玉子的传粉小蜂进行分析,结果表明:(1)薜荔传粉小蜂和爱玉子传粉小蜂的核糖体28S序列的碱基组成中A,T,G,C 4种含量较平均,C+G的平均含量(56%)稍高于A+T的含量(44%)。线粒体Cytb序列中A+T的含量(76.1%)明显高于C+G的含量(23.9%),COI序列中A+T的含量(71.9%)也明显高于G+C的含量(28.1%),这是膜翅目昆虫线粒体基因的普遍特征。在薜荔和爱玉子传粉小蜂的线粒体Cytb及COI基因中,密码子第三位点A+T的含量最高。(2)比较薜荔和爱玉子传粉小蜂的3种分子标记的变异范围显示,28S进化速度较Cytb及COI序列慢,比较保守,更适合科、亚科等较高分类单元的研究。薜荔传粉小蜂与爱玉子传粉小蜂之间的亲缘关系较近,采用Cytb与COI序列进行分析更为精确。(3)用Cytb及COI序列对薜荔传粉小蜂与爱玉子传粉小蜂之间的遗传距离进行分析显示,薜荔传粉榕小蜂个体间Cytb序列平均遗传距离为0.0054,爱玉子传粉小蜂个体间的Cytb遗传距离为0.0164;薜荔传粉小蜂与爱玉子传粉小蜂群体之间的Cytb序列平均遗传距离为0.1385;COI序列的薜荔传粉榕小蜂个体间遗传距离为0.0048,爱玉子传粉小蜂各样本间平均遗传距离为0.0102;薜荔传粉小蜂与爱玉子传粉小蜂群体间COI序列平均遗传距离为0.1896,两群体间的遗传距离(差异大于10%以上)明显大于群体内各样本之间的遗传距离,表明薜荔传粉小蜂与爱玉子传粉小蜂之间已经发生了很大的遗传分化,其变异水平达到了种间分化水平,即薜荔传粉小蜂与爱玉子传粉小蜂为两个不同的种。     

Correlates of subordinate behaviour in the cockroach, Nauphoeta cinerea

Some characteristics of the dominant-subordinate relationship in the cockroach Nauphoeta cinerea were determined. Dominance could be reversed by experience with other animals, and individual recognition did not play a role in maintaining the relationship. The initial effects of subordination disappeared with increasing periods of separation before re-pairing and reversal may be observed. Exposure to artificial stress reversed the behaviour of both dominant and subordinate. A physiological correlate of subordinate behaviour was found. The results are related to current theories on insect stress physiology.     

Releasing signals of oviposition behaviour in Bombyx mori

The oviposition behaviour of Bombyx mori was studied by eliminating the sensory input received by the tactile setae of the anal papillae.It is shown that the removal of mechanical stimuli of the setae affects oviposition and its time course to some extent. In comparing this experimental result with the theory of Lorenz, summarized in the ‘hydromechanic model’, it is postulated that the sensory information from the mechanoreceptive setae surrounding the ovipositor is a key stimulus which releases the accumulated action-specific energy (‘drive’) and triggers and controls the organs involved in the behaviour.     

Sexual and agonistic behaviour in the killdeer (Charadrius vociferus)

Field studies suggest that killdeer pairs form on the breeding grounds. Males advertise both on the ground and in the air with loud ‘killdeer’ and other calls and with scraping (‘sham’ nesting). In scrape exchanges the scraper faces away, breast dipped, tail raised and spread over the incoming bird. On the ground killdeers chase with body horizontal, back feathers ruffled and trilled calls. Fleers are silent and may end runs with sudden crouched tilting of the dorsum toward the pursuer, exposing the reddish rump. Pairs defend their nest area and young from conspecifics.