Teratological deformities of pedipalps in the Tegenaria atrica spider,induced by low and high temperatures applied alternately

The study was aimed at demonstrating the relationship between temperature (as a factor which disturbs morphogenesis) and deformities in the front part of the prosoma in Tegenaria atrica. By exposing spider embryos to alternating temperatures of 14 and 32 °C for the first 10 days of embryonic development, i.e. until the first metameres of the prosoma appeared on the germ band, we obtained individuals with a range of anomalies including those which affected the prosomal morphology. We selected five spiders with deformities of pedipalps or of pedipalps and walking legs for comprehensive analysis. The results indicate a relationship between temperature applied as a teratogenic factor and anomalies in the front part of the prosoma.     

Agonistic behaviour of female Tegenaria atrica in the presence of different aged spiderlings

The agonistic behaviour of adult female T. atrica increases with increasing age of spiderlings until 80 days post-emergence, then decreases. In all cases, cannibalism of spiderlings increases markedly after completion of their pre-dispersal period with a correlation between the switch of behaviour, from tolerance to cannibalism, and a modification of individual’s cuticular compounds. Experiments that compare spiderlings weight and mobility indicate that female agonistic behaviour are always low with spiderlings in pre-dispersal period, and high with spiderlings in post-dispersal period. Female reproductive state and the weight/mobility of spiderlings are not the only factors controlling the adult female’s agonistic behaviour towards spiderlings on her web, as tactochemical information plays an important role in modulating agonistic behaviour after close contact between female spiders and spiderlings. The agonistic behaviour of females appears to correspond with a change in the increase of polar compound levels (methylesters and fatty acids) and the decrease of apolar compound levels (hydrocarbons) in spiderlings of different ages.     

Contrasting patterns of hybridization in large house spiders (Tegenaria atrica group, Agelenidae)

The integrity of species is not fixed and may vary geographically. Here we investigate the geographic distributions and interactions of species in the Tegenaria atrica group (Araneae: Agelenidae). Detailed mapping of T. saeva and T. gigantea in England and Wales shows them to be broadly allopatric in southern England with a tightly defined, and possibly long-standing, narrow zone of parapatry in central southern England. In the north of England (Yorkshire), by contrast, the species are broadly sympatric as a result of recent range expansions. GIS techniques are used to map the species distributions and to quantify, we believe for the first time, the intimacy of interspecific interactions. The extent and nature of hybridization in these two areas is examined through regression and multivariate analyses of morphology. We show that the relative incidence of hybridization is much greater in Yorkshire than within the parapatric zone in the south. Clear patterns of asymmetric introgression are observed in both northern and southern England, with a greater impact of T. gigantea on T. saeva than vice versa. We find no sign of morphological reproductive character displacement at the zone of parapatry that might indicate reinforcement, although we cannot exclude more subtle effects, for example via cuticular pheromones. The integrity of these two species seems to be breaking down in northern England, a process that might gain momentum as the gene pools become more similar.     

用非线性模型估测恒温和变温下棉铃虫蛹的发育率

为了深入分析和探讨昆虫发育与环境温度的关系, 在恒温（15~37℃）和交替变温（12/18~34/40℃）下测定了棉铃虫Helicoverpa armigera蛹的发育历期(d),分别用线性模型和非线性模型（Logan模型﹑Lactin模型和王氏模型）拟合其发育率(1/d)数据。结果表明,这3个非线性模型能更准确地描述发育率与温度之间的曲线关系,判定系数（R2）在0.9878～0.9991之间。对全部观测数据的进一步研究表明,只要有6个分布合适的观测数据,就可以用这些非线性模型获得相当满意的估测效果。如果缺乏高温下的测定数据,用非线性模型预测的昆虫发育率可能失真。分析了蛹在恒温和变温下发育率差异的可能原因,讨论了应用这3个非线性模型预测蛹期发育的优点和缺点,指出用非线性模型取代线性日·度模型进行害虫发生预测和益虫饲养管理的合理性和必要性。     

Species specific chlorophyll a fluorescence-temperature profile at high temperatures in the leaves

Chlorophyll a (Chl a) fluorescence-temperature profile in the region of 20–80°C was recorded for fourteen different plant species. In all the species studied, there was a rise in the fluorescence intensity in the region of 45–50°C and around 55°C the fluorescence intensity started to decline. In four of the species (Acacia melanoxylon, Ervatamia montana, Eucalyptus tertecornius and Azardicta indica) tested, there was a secondary rise in the fluorescence intensity around 65–70°C whereas in all other species a sharp decline in the fluorescence intensity was observed at this point. These changes in the fluorescence intensity at high temperatures (65–70°C) appear to be species specific and cannot be explained either in terms of changes in the stoichiometry between the two photosystems or in terms of Chl a fluorescence emission from photosystem I (PS I) at higher temperatures. This conclusion is supported by following observations: (1) there was no definite correlation between the Chl a/Chl b ratio and the pattern of fluorescence-temperature profile at high temperatures; (2) the sun and shade plants of the same species had a similar pattern of fluorescence-temperature profile; and (3) preferential excitation of PS I did not alter the fluorescence-temperature profile.Abbreviations Chl chlorophyll - PS photosystem     

The consequences of freezing temperatures followed by high irradiance on in vivo chlorophyll fluorescence and growth in Picea abies

Picea abies (L.) Karst. plants, propagated by cuttings, were subjected to one night of freezing temperatures (-5°C), high irradiance (1 200 or 1 800 μmol m⁻² s⁻¹), or freezing temperatures followed by high irradiance. The treatments were applied at bud burst, at time of shoot elongation, and when the shoots had ceased to elongate. The maximum quantum yield of photosynthesis, F_v/F_m, dry weight of branches and needles, and length and survival of shoots were measured. F_v/F_m and growth decreased after a night of freezing temperatures followed by high irradiance, at the time of bud burst and shoot elongation. High irradiance alone influenced F_v/F_m, but not growth. Freezing temperatures affected F_v/F_m, and growth at the time of shoot elongation. F₀ increased after a night of freezing temperatures and decreased with age of the current-year needles. It was concluded that the use of short-term measurements of chlorophyll fluorescence induction to predict changes in growth after a night of frost and subsequent high light was not a reliable method.     

A true summer diapause induced by high temperatures in the cotton bollworm, Helicoverpa armigera (Lepidoptera: Noctuidae)

Summer diapause in the cotton bollworm, Helicoverpa armigera (Hübner), which prolongs the pupal stage, particularly in males, is induced by high temperatures. In the laboratory, summer-diapausing pupae of H. armigera were induced at high temperatures (33-39 degrees C) with a photoperiod of LD8:16; winter-diapausing and non-diapausing pupae, cultured at 20 degrees C with a photoperiod of LD8:16 and at 27 degrees C, LD16:8, respectively, acted as a control. Retention time of eye spots, weight, and lipid and glycogen levels were compared. At high temperatures, both body weight and energy storage capacity were much higher in summer-diapausing pupae than in non-diapausing pupae reared at 33-39 degrees C. At temperatures (>33 degrees C) high enough to maintain summer diapause, the eye spots of summer-diapausing pupae did not move during the 30-day experiment. However, eye spots of summer-diapausing pupae placed at 30 degrees C began to move about 10 days after they were transferred, significantly later than in non-diapausing pupae reared at 33-39 degrees C or non-diapausing pupae reared at 27 degrees C, which initiated eye spot movement 2 days after pupation. The differences in retention time of eye spots between summer- and winter-diapausing pupae shows that winter diapause is more intense than summer diapause in this insect. The weight loss, and lipid and glycogen metabolism curves indicate that the summer-diapausing pupae's metabolism is very low. We conclude that summer diapause in the cotton bollworm is a true diapause and that the summer diapause enables the cotton bollworm to withstand the high temperatures of summer.     

Energy budget changes caused by varying solar angles,cloud scenarios,and air temperatures in contrasting landscapes

The combination of two physically-based models of solar radiationcloud attenuation and a steady state surface energy budget made possible the systematic examination of the causal effects of varying solar altitudes, selected cloud types and amounts, and air temperatures on the resultant energy budget components extant in two contrasting (grassy and barren) landscapes. The grassy landscape reacted more conservatively to the forcing by changing solar angles, cloud, and air temperature regimes. The results are considered as universal and they are assumed to encompass many possible extremes encountered in the continuum formed by real world landscapes.     

Heterozygosity and fitness in a California population of the labyrinth spider Metepeira ventura (Araneae, Araneidae)

Abstract. The relationship between individual heterozygosity and characteristics likely to be associated with fitness was investigated in the labyrinth spider Metepeira ventura . Adult females and their egg sacs were collected at a coastal site in southern California, and three measures of bodily condition (carapace width, weight, residual index) and six measures of reproductive output (number of egg sacs, variation in egg number among sacs [coefficient of variation], total number of eggs, mean eggs/sac, mean eggs/sac divided by carapace width, mean eggs/sac divided by weight) were determined for each spider. The sample was polymorphic at three allozyme loci that were in Hardy–Weinberg equilibrium, and individual females were heterozygous at up to two of the three loci, forming three heterozygosity classes (0, 1, and 2). None of the bodily condition measures were significantly related to the number of heterozygous loci, while four of the reproductive output estimators (total number of eggs, mean eggs/sac, mean eggs/sac divided by carapace width, mean eggs/sac divided by weight) were significantly influenced by heterozygosity. In each significant case, values for class 2 females were less than those for class 0 and 1 females, whose values were usually more similar. Thus, while female bodily condition was comparable among classes, the most heterozygous females produced fewer total eggs and eggs per sac than their less heterozygous peers. The fact that females of M. ventura engage in a reproductive investment-number trade-off suggests that high-variability and low-variability females may be pursuing distinct reproductive strategies in the wild, with more heterozygous females being K -selected (smaller clutches, heavier eggs) and more homozygous females being r -selected (larger clutches, lighter eggs). Further investigation will be needed to assess more fully the fitness value of heterozygosity in M. ventura .     

Abnormal spermatogenesis at low temperatures in the Japanese red-bellied newt,Cynops pyrrhogaster: possible biological significance of the cessation of spermatocytogenesis

In newt testis, spermatocytes never appear during winter, because secondary spermatogonia die by apoptosis just before meiosis. In the current study, we examined the effect of low temperatures on spermatogenesis. Incubation of newts at low temperatures (8, 12, 15 degrees C) induced defects in spermatogenesis in a temperature-dependent manner. At 8 degrees C, multinucleated giant cells (MGCs) were observed in spermatocytes and spermatogenesis never proceeded beyond meiosis. Although spermatocytes completed meiotic divisions at 12 degrees C, severe cell death was observed in the spermatids. At 15 degrees C both normal and abnormal spermiogenesis were observed. Under these conditions, impaired meiotic synapsis/recombination and down-regulation of the expression of the DMC1 protein, which play pivotal roles in meiotic pairing in eukaryotes, were also observed. Furthermore, to examine the quality of the sperm produced at low temperature for supporting development, artificial insemination was performed. The eggs inseminated with spermatozoa derived from newts kept at 15 degrees C demonstrated a restricted developmental capacity, even though these spermatozoa had an equal capacity for carrying out fertilization to those kept at 22 degrees C. These results suggest that meiosis at low temperatures cause the production of abnormal spermatozoa. Conservation and the significance of this phenomenon in poikilothermic vertebrates living in the temperate zones are also discussed.     

Growth,stress, and acclimation responses to fluctuating temperatures in field and domesticated populations of Manduca sexta

Diurnal fluctuations in temperature are ubiquitous in terrestrial environments, and insects and other ectotherms have evolved to tolerate or acclimate to such fluctuations. Few studies have examined whether ectotherms acclimate to diurnal temperature fluctuations, or how natural and domesticated populations differ in their responses to diurnal fluctuations. We examine how diurnally fluctuating temperatures during development affect growth, acclimation, and stress responses for two populations of Manduca sexta: a field population that typically experiences wide variation in mean and fluctuations in temperature, and a laboratory population that has been domesticated in nearly constant temperatures for more than 300 generations. Laboratory experiments showed that diurnal fluctuations throughout larval development reduced pupal mass for the laboratory but not the field population. The differing effects of diurnal fluctuations were greatest at higher mean temperature (30°C): Here diurnal fluctuations reduced pupal mass and increased pupal development time for the laboratory population, but had little effect for the field population. We also evaluated how mean and fluctuations in temperature during early larval development affected growth rate during the final larval instar as a function of test temperature. At an intermediate (25°C) mean temperature, both the laboratory and field population showed a positive acclimation response to diurnal fluctuations, in which subsequent growth rate was significantly higher at most test temperatures. In contrast at higher mean temperature (30°C), diurnal fluctuations significantly reduced subsequent growth rate at most test temperatures for the laboratory population, but not for the field population. These results suggest that during domestication in constant temperatures, the laboratory population has lost the capacity to tolerate or acclimate to high and fluctuating temperatures. Population differences in acclimation capacity in response to temperature fluctuations have not been previously demonstrated, but they may be important for understanding the evolution of reaction norms and performance curves.     

Exome sequencing reveled a compound heterozygous mutations in RTTN gene causing developmental delay and primary microcephaly

RTTN (Rotatin) (OMIM 614833) is a large centrosomal protein coding gene. RTTN mutations are responsible for syndromic forms of malformation of brain development, leading to polymicrogyria, microcephaly, primordial dwarfism, seizure along with many other malformations. In this study we have identified a compound heterozygous mutation in RTTN gene having NM_173630 c.5225A > G p.His1742Arg in exon 39 and NM_173630 c.6038G > T p.Cys2013Phe in exon 45 of a consanguineous Saudi family leading to brain malformation, seizure, developmental delay, dysmorphic feature and microcephaly. Whole exome sequencing (WES) techniques was used to identify the causative mutation in the affected members of the family. WES data analysis was done and obtained data were further confirmed by using Sanger sequencing analysis. Moreover, the mutation was ruled out in 100 healthy control from normal population. To the best of our knowledge the novel compound heterozygous mutation observed in this study is the first report from Saudi Arabia. The identified compound heterozygous mutation will further explain the role of RTTN gene in development of microcephaly and neurodevelopmental disorders.     

Warm developmental temperatures induce non-adaptive plasticity in the intrasexually selected colouration of a dragonfly

1. When the breeding environment fluctuates across generations, reproductive traits may evolve plasticity that optimises the balance between survival and mating success for the prevailing environment. 2. For sexually selected colouration, this balance can depend on environmental temperatures. Accordingly, breeding colouration often co-varies with temperature through space and time. However, whether such traits exhibit plasticity in response to environmental temperatures is poorly understood. 3. In the present study, a dragonfly (Pachydiplax longipennis) was reared under ambient or experimentally warmed conditions and tested for plasticity in its intrasexually selected wing colouration. Although wing colouration improves male territorial success, these advantages are smaller under warmer conditions than cooler conditions. It was therefore predicted that males reared under the ambient thermal conditions of the study site (Cleveland, Ohio) would develop more wing colouration than those reared under experimentally warmed conditions. 4. Contrary to this prediction, males reared in warm larval temperatures produced more wing colouration. Thus, although the secondary sexual colouration of this species displays some thermal plasticity, it does not appear to be adaptive relative to the known thermal variation of intrasexual selection in this population. 5. Given that the environment often determines the strength and direction of sexual selection, future studies should consider the potential for non-adaptive, and even maladaptive, developmental plasticity in the sexually selected traits of insects.     

大兴安岭林区不同植被对冻土地温的影响

植被常常通过反射太阳辐射、遮阳、蒸腾散热、阻风挡雪、保水吸水等来影响下伏多年冻土.但是不同的植被类型,对下伏冻土热状况的影响也不尽相同.为了探讨大兴安岭林区不同植被对冻土的影响,选取大兴安岭森林生态站实验区杜香-真藓-落叶松林、真藓-落叶松林、塔头-落叶松林、柴桦落叶松林和伊图里河镇原冻土观测场塔头湿地5种典型林型,分析不同林型对冻土的温度和冻融作用的影响.研究发现不同林型的不同组分,由于反射率、覆盖度和根系吸水能力的差别,使得各种林型下的地面温度也不相同.在夏季,月平均地面温度从高到低依次为真藓-落叶松林、杜香-真藓-落叶松林、伊图里河塔头湿地、柴桦落叶松林和塔头落叶松林.由于塔头落叶松林存在乔木层和灌木层,与伊图里河塔头湿地相比,8月份平均地面温度差值低10℃以上.柴桦落叶松林两个钻孔的对比实验表明,铲除地表植被会使活动层0.8 m以上部分的地温升高,并且主要发生在8、9、10月份.对冻土而言,林区植被暖季降温的贡献大于冷季增温的贡献.另外,塔头一落叶松林根系吸水能力最强,这种林型下的土壤开始融化和冻结的日期最晚,冻结初期地面降温速率为0.1 ℃/d,而0.2 m以下降温速率几乎为零.同样柴桦落叶松林的塔头根系吸水能力使得其0.5 m和0.8 m的降温速率低于除塔头落叶松林外的其他林型,但是地面上植物的凋零和枯萎会加快地面的冻结速率.真藓-落叶松林的乔灌木层发育不好,地面降温速率大于杜香-真藓-落叶松林和伊图里河塔头湿地,而伊图里河塔头湿地由于没有乔灌木层的庇护,地面以下的降温速率高于其他林型.     

Crystal Structure of CCM3, a Cerebral Cavernous Malformation Protein Critical for Vascular Integrity

CCM3 mutations are associated with cerebral cavernous malformation (CCM), a disease affecting 0.1–0.5% of the human population. CCM3 (PDCD10, TFAR15) is thought to form a CCM complex with CCM1 and CCM2; however, the molecular basis for these interactions is not known. We have determined the 2.5 Å crystal structure of CCM3. This structure shows an all α-helical protein containing two domains, an N-terminal dimerization domain with a fold not previously observed, and a C-terminal focal adhesion targeting (FAT)-homology domain. We show that CCM3 binds CCM2 via this FAT-homology domain and that mutation of a highly conserved FAK-like hydrophobic pocket (HP1) abrogates CCM3-CCM2 interaction. This CCM3 FAT-homology domain also interacts with paxillin LD motifs using the same surface, and partial CCM3 co-localization with paxillin in cells is lost on HP1 mutation. Disease-related CCM3 truncations affect the FAT-homology domain suggesting a role for the FAT-homology domain in the etiology of CCM.     

Oxidative damage of rat cerebral cortex and hippocampus,and changes in antioxidative defense systems caused by hyperoxia

In order to elucidate the oxidative damage in rat brain caused by oxidative stress, regional changes in the levels of lipid peroxidation products and antioxidative defense systems in cerebral cortex and hippocampus, and in their synapses, which modulate learning and memory functions in the brain, were studied. When rats were subjected to hyperoxia as an oxidative stress, thiobarbituric acid reactive substance (TBARS) in the regions studied increased more than in normal rats by approximately 35%. The values in oxygen-unexposed vitamin E-deficient rats were also higher than in normal rats. It was found that the TBARS contents in synaptosomes isolated from both regions were remarkably higher than in the organs. These results imply that synapses are more susceptible to oxidative stress than the organ itself. This tendency was also observed in the content of conjugated diene. In response to oxidative stress, the status of the antioxidant defense system in each region, i.e. the concentration of vitamin E, and the activities of superoxide dismutase, catalase and glutathione peroxidase, decreased remarkably. On the other hand, in oxygen-unexposed vitamin E-deficient rats, the activities of these enzymes in each region tended to increase, except for catalase activity. These results suggest that in response to the oxidative stress, the antioxidant defense systems may be consumed to prevent oxidative damage, and then, may be supplied through the antioxidant network.     

海南捕鸟蛛毒素-IV对大鼠背根神经节细胞钠通道的抑制影响(英文)

海南捕鸟蛛毒素 IV(HNTX IV)是从中国捕鸟蛛Seleconosmiahainana粗毒中分离得到的一种肽类神经毒素 ,在成年大鼠背根神经节 (DRG)细胞上观察了该毒素对电压门控钠通道的影响。在全细胞膜片钳条件下 ,HNTX IV能明显抑制哺乳动物神经性河豚毒敏感型 (TTX S)钠电流 ,但不影响河豚毒不敏感型 (TTX R)钠电流。HNTX IV对DRG细胞TTX S钠电流的抑制作用具有浓度依从性 ,其有效半抑制浓度 (IC50 )为 44 .6nmol/L。该毒素不影响DRG钠电流的激活与失活时间特征 ,但能导致钠通道的半数稳态失活电压向超极化方向漂移约 10 .1mV。结果表明HNTX IV是一种新型的蜘蛛毒素 ,其影响电压门控钠通道的机制可能有别于那些结合于通道位点 3来延缓钠电流失活时间特征的蜘蛛毒素如δ 澳洲漏斗网蛛毒素、μ 美洲漏斗网蛛毒素I VI等。     

Naturally occurring broad-spectrum powdery mildew resistance in a Central American tomato accession is caused by loss of mlo function

The resistant cherry tomato (Solanum lycopersicum var. cerasiforme) line LC-95, derived from an accession collected in Ecuador, harbors a natural allele (ol-2) that confers broad-spectrum and recessively inherited resistance to powdery mildew (Oidium neolycopersici). As both the genetic and phytopathological characteristics of ol-2-mediated resistance are reminiscent of powdery mildew immunity conferred by loss-of-function mlo alleles in barley and Arabidopsis, we initiated a candidate-gene approach to clone Ol-2. A tomato Mlo gene (SlMlo1) with high sequence-relatedness to barley Mlo and Arabidopsis AtMLO2 mapped to the chromosomal region harboring the Ol-2 locus. Complementation experiments using transgenic tomato lines as well as virus-induced gene silencing assays suggested that loss of SlMlo1 function is responsible for powdery mildew resistance conferred by ol-2. In progeny of a cross between a resistant line bearing ol-2 and the susceptible tomato cultivar Moneymaker, a 19-bp deletion disrupting the SlMlo1 coding region cosegregated with resistance. This polymorphism results in a frameshift and, thus, a truncated nonfunctional SlMlo1 protein. Our findings reveal the second example of a natural mlo mutant that possibly arose post-domestication, suggesting that natural mlo alleles might be evolutionarily short-lived due to fitness costs related to loss of mlo function.