酵母交配过程的极性生长及其调控机制

酿酒酵母单倍体细胞能够与相反交配型的单倍体细胞发生交配。交配时酿酒酵母放弃原有出芽位点,根据信息素的浓度梯度,重新选择生长位点,向相反交配型细胞伸出突起进行极性生长。交配因子受体指导选择交配突起的位点,通过G蛋白激活Ste20p,将信号经由Ste11p、Ste7p和Fus3p组成的MAPK模块传递到Far1p和Ste12p等因子,调控相关基因的转录,抑制原有的出芽位点,选择新的生长位点,并使细胞周期停止在G1期,G蛋白与Cdc24p、Cdc42p和Bem1p等蛋白作用,聚集在细胞,使得肌协蛋白细胞骨架在交配突起处聚集,呈极性化分布,使细胞发生极性生长。     

昆虫交配因子及其分子基础

概述了目前昆虫交配因子的研究概况,包括昆虫交配因子的来源、类别、对雌虫行为和性信息素滴度的影响;在雌虫体内的传递路径及作用机理,以及交配因子的分子生物学研究。     

Pheromone pre-exposure and mating modulate codling moth (Lepidoptera: Tortricidae) response to host plant volatiles

Abstract 1 Two codling moth Cydia pomonella kairomonal attractants, ethyl (E,Z)‐2,4‐decadienoate (pear ester) and (E)‐β‐farnesene, were tested in an insecticide‐sprayed apple orchard and an orchard treated for mating disruption with synthetic pheromone (E,E)‐8,10‐dodecadienol (codlemone). Male captures with pear ester were higher in the pheromone‐treated than in the insecticide‐treated orchard, whereas captures with (E)‐β‐farnesene were not different. Subsequent wind tunnel experiments confirmed that pre‐exposure to sex pheromone codlemone increased the behavioural response of codling moth males to pear ester. This supports the idea that male attraction to the plant volatile pear ester and sex pheromone codlemone is mediated through the same sensory channels. 2 Pear ester is a bisexual codling moth attractant and even captures of female moths were significantly increased in the pheromone‐treated orchard. In the laboratory wind tunnel, pheromone pre‐exposure had no effect on female response to pear ester, but significantly more mated than unmated codling moth females flew upwind towards a pear ester source. Differences in mating status in insecticide‐treated vs. pheromone‐treated orchards may thus account for the differences in female trap captures with pear ester. 3 These findings are important with respect to monitoring of codling moth with pear ester in mating disruption orchards. They also emphasize the importance of host plant volatiles in pheromone‐mediated mating disruption, which has been neglected to date.     

Nucleocytoplasmic shuttling of the Cdc42p exchange factor Cdc24p

Cdc24p, the GDP/GTP exchange factor for the regulator of actin cytoskeleton Cdc42p, localizes to sites of polarized growth. Here we show that Cdc24p shuttles in and out of the yeast nucleus during vegetative growth. Far1p is necessary and sufficient for nuclear accumulation of Cdc24p, suggesting that its nuclear import occurs via an association with Far1p. Nuclear export is triggered either by entry into the cell cycle or by mating pheromone. As Far1p is degraded upon entry into the cell cycle, cell cycle-dependent export of Cdc24p occurs in the absence of Far1p, whereas during mating similar export kinetics indicate that a Cdc24p-Far1p complex is exported. Our results suggest that the nucleus serves as a store of preformed Cdc24p-Far1p complex which is required for chemotropism.     

小地老虎的交配行为和能力

在温度为(25±1)℃、相对湿度为70%±7%、光周期(L∶D)为14∶10h的条件下对小地老虎Agrotis ypsilon(Rottemberg)的交配行为和能力进行研究。结果表明:成虫在羽化后1d才进行交配。雄蛾和雌蛾都可以多次交配。交配能力受性比的影响很大,当1头雄蛾仅与1头雌蛾相处时,其交配能力低;当1头雄蛾与多于2头的雌蛾在一起时或1头雌蛾与多于2头的雄蛾在一起时,交配能力则显著增加。还讨论了该研究结果应用的可能性。     

Mate and fuse: how yeast cells do it

Many cells are able to orient themselves in a non-uniform environment by responding to localized cues. This leads to a polarized cellular response, where the cell can either grow or move towards the cue source. Fungal haploid cells secrete pheromones to signal mating, and respond by growing a mating projection towards a potential mate. Upon contact of the two partner cells, these fuse to form a diploid zygote. In this review, we present our current knowledge on the processes of mating signalling, pheromone-dependent polarized growth and cell fusion in Saccharomyces cerevisiae and Schizosaccharomyces pombe, two highly divergent ascomycete yeast models. While the global architecture of the mating response is very similar between these two species, they differ significantly both in their mating physiologies and in the molecular connections between pheromone perception and downstream responses. The use of both yeast models helps enlighten both conserved solutions and species-specific adaptations to a general biological problem.     

Ligand Recognition in Multiallelic Pheromone Receptors from the Basidiomycete Schizophyllum commune Studied in Yeast

The homobasidiomycete Schizophyllum commune encodes a multiallelic pheromone receptor system that distinguishes more than 20 nonself from at least 2 self pheromones. The well-investigated pheromone response system of the yeast Saccharomyces cerevisiae was used to link the FUS1::lacZ reporter system to the heterologous pheromone receptors from S. commune. To investigate yeast G-protein binding, the unchanged heterologous receptor was compared to constructs carrying an exchange of the 3rd cytoplasmatic loop for the Ste2 sequence. A better coupling could be achieved with the altered constructs. In order to examine activation by single pheromones, an artificial peptide based on the sequence of a new putative pheromone gene, bap2(1), in the Balpha2 mating-type locus encoding the shortest pheromone found so far in fungal mating types was used. Thus, we have reassembled the pheromone recognition of the basidiomycete S. commune and constructed a system ideal for specificity analysis in the yeast S. cerevisiae.     

豆野螟成虫日龄对交尾的影响及雄蛾对性信息素的触角电位反应

豆野螟Marucavitrata(Fabricius)是一种严重的泛热带豆类蔬菜害虫。在不同温度,光周期14L∶10D,相对湿度75%～80%条件下,研究豆野螟成虫日龄对交尾的影响及雄蛾对性信息素的EAG反应。不同日龄雌蛾与3日龄雄蛾的交尾,交尾率随蛾龄增加呈下降趋势;不同日龄雄蛾与3日龄雌蛾交尾,交尾率随蛾龄增加呈升高趋势;相同日龄成蛾,交尾率先升后降。不同日龄雌蛾交尾百分率的下降在较高温环境比在较低温环境更加显著;但环境温度对不同日龄雄蛾的交尾却没有太大的影响;相同日龄成蛾3日龄以后的交尾在较高温环境下下降的更快。不同日龄雌蛾的交尾研究中,随着雌蛾日龄的增加,交尾持续时间明显延长;不同日龄雄蛾的交尾研究中,较低日龄和较高日龄雄蛾交尾时的持续时间较长。在较低温环境下所有试验各日龄的持续时间均有所延长。不同日龄雌蛾(雄蛾)与3日龄雄蛾(雌蛾)的交尾和相对应的雄蛾对雌蛾性信息素的EAG反应基本一致,说明雄蛾的反应在交尾行为的完成中具有重要的作用。     

Pheromone puffs suppress mating by Plodia interpunctella and Sitotroga cerealella in an infested corn store

The efficacy of pheromone mating disruption was investigated in a 7×6×3 m corn storage room harboring a high population density of Indian meal moth, Plodia interpunctella (Hübner) and Angoumois grain moth, Sitotroga cerealella (Olivier). Pheromones were released from a controlled release dispenser, the metered semiochemical timed release system (MSTRS^TM) at emission rates of 0.6 g min^–1 (Z9,E12:14:Ac for Indian meal moth) and 0.2 g min^–1 (Z7,E11-16:Ac for Angouimois grain moth). Mating disruption efficacy was evaluated using three parameters: male capture in pheromone traps, visual examination of mating behavior, and the incidence and frequency of mating as measured by spermatophores. In three trials, comparisons were made between data collected before pheromone treatment and during treatment. Disruption of pheromone source location by males averaged 70% and 40% for P. interpunctella and S. cerealella, respectively, in the three trials. In addition, reduced levels of copulation by both species were recorded during pheromone treatment. More importantly, significant reductions were recorded in the incidence and frequency of mating by females of both species collected during the treatment period. While 85% of P. interpunctella females collected before pheromone treatment in three trials had mated at least once, only 50% of the females collected during treatment had mated. The mean number of matings, as measured by spermatophores, ranged between 0.8–1.1 and 0.5–0.7 before and during pheromone treatment, respectively. Similarly, a 20–30% reduction in the proportion of mated S. cerealella females was recorded during pheromone treatment. In the three trials, mean number of spermatophores per S. cerealella female averaged 1.0 and 0.7 during the pretreatment and treatment periods, respectively. Additional tests conducted in small boxes also recorded significant mating disruption of both species.     

Scanning mutagenesis of regions in the Gα protein Gpa1 that are predicted to interact with yeast mating pheromone receptors

The mechanism by which receptors activate heterotrimeric G proteins was examined by scanning mutagenesis of the Saccharomyces cerevisiae pheromone-responsive Gα protein (Gpa1). The juxtaposition of high-resolution structures for rhodopsin and its cognate G protein transducin predicted that at least six regions of Gα are in close proximity to the receptor. Mutagenesis was targeted to residues in these domains in Gpa1, which included four loop regions (β2–β3, α2–β4, α3–β5, and α4–β6) as well as the N and C termini. The mutants displayed a range of phenotypes from nonsignaling to constitutive activation of the pheromone pathway. The constitutive activity of some mutants could be explained by decreased production of Gpa1, which permits unregulated signaling by Gβγ. However, the constitutive activity caused by the F344C and E335C mutations in the α2–β4 loop and F378C in the α3–β5 loop was not due to decreased protein levels, and was apparently due to defects in sequestering Gβγ. The strongest loss of the function mutant, which was not detectably induced by a pheromone, was caused by a K314C substitution in the β2–β3 loop. Several other mutations caused weak signaling phenotypes. Altogether, these results suggest that residues in different interface regions of Gα contribute to activation of signaling.     

Cockroach mating behaviors,sex pheromones,and abdominal glands (Dictyoptera: Blaberidae)

Two chemical signals are essential in all cockroach sexual behavioral sequences: the sex pheromone released by one partner, generally the female (for long distance attraction), and an aphrodisiac sex pheromone produced exclusively by male tergal glands (for female mounting and tergal contact or feeding behavior). Unlike the other cockroach groups, the males of the Oxyhaloinae species produce both chemical signals: the pheromone and the aphrodisiac. The occurrence of three patterns of mating behavior (A, B, and C), the production of male sex pheromones, and the existence in the male of developed sternal and tergal glands in seven related Oxyhaloinae species, make these cockroaches a useful model for studying the evolution of mating behavior patterns. The various types of mating behavior were not classified in the previous studies by Roth and Barth. In this report, they have been named type A (female in upper position), B (male in upper position), and C (male and female end to end). In type A mating, the male tergal glands, which are licked by the females, are well developed, whereas in types B and C, there is no licking of the male's tergal secretion by the females and the tergal glands are much less developed; the aphrodisiacs secreted by the tergal glands may no longer act in this case through contact chemoreception, but through an olfactory process involving volatile components. One common sex pheromone component seems to be acetoin. I suggest that the mating behavior tends from A toward B and C during the evolutionary process with a concomitant regression of the tergal glands and changes in the aphrodisiac emission levels. The mating behavioral sequences of cockroaches (Dictyoptera) and crickets (Orthoptera) show a striking degree of similarity and are probably examples of convergent evolution.     

亚洲玉米螟交配率和交配次数与其日龄、性比和精巢大小的关系

【目的】昆虫交配行为与其日龄和生殖系统发育密切相关。本研究旨在明确亚洲玉米螟Ostrinia furnacalis交配行为与其日龄、性比和雄蛾精巢大小的关系,为性信息素群集诱杀和交配干扰防控亚洲玉米螟提供理论依据。【方法】通过室内交配实验测定了不同配对晚数、日龄、性比亚洲玉米螟的交配率和交配次数,通过雄蛾精巢解剖分析了交配次数与精巢体积的关系。【结果】亚洲玉米螟的交配率随配对晚数增加而增加,但第1-5晚的增加速度大于第6-7晚的;1-4日龄蛾的交配率随日龄增加而增加,5日龄蛾的交配率显著降低;1-3日龄蛾配对1晚的交配率与新羽化蛾配对2～4晚的均无显著差异。亚洲玉米螟可以交配1～3次,但是交配3次的比例极低。雌性数量从1增为2时,雄蛾的交配率显著增加;从2增为3时,雄蛾的交配率显著降低、死亡率显著增加,交配1次的雄蛾进行二次交配的比例也增加,并且雄蛾更愿意与处女雌蛾进行第2次交配;交配1次雄蛾的精巢体积总是显著大于同期未交配雄蛾的,交配1次稍降低了雄蛾精巢的衰退速度,交配2次则明显增加雄蛾精巢的衰退速度。【结论】本研究明确了亚洲玉米螟交配与日龄、性比和雄蛾精巢体积之间的关系,从理论上证...     

T47D breast cancer cell growth is inhibited by expression of VACM-1, a cul-5 gene

Vasopressin-activated calcium-mobilizing (VACM-1), a cul-5 gene, is localized on chromosome 11q22-23 close to the gene for Ataxia Telangiectasia in a region associated with a loss of heterozygosity in breast cancer tumor samples. To examine the biological role of VACM-1, we studied the effect of VACM-1 expression on cellular growth and gene expression in T47D breast cancer cells. Immunocytochemistry studies demonstrated that VACM-1 was expressed in 0.6-6% of the T47D cells and localized to the nucleus of mitotic cells. Overexpressing VACM-1 significantly attenuated cellular proliferation and MAPK phosphorylation when compared to the control cells. In addition, VACM-1 decreased egr-1 and increased Fas-L mRNA levels. Further, egr-1 protein levels were significantly lower in the nuclear fraction from VACM-1 transfected cells when compared to controls. These data indicate that VACM-1 is involved in the regulation of cellular growth.     

Reproductive biology and function of multiple mating in the mating system of a tree cricket,Truljalia hibinonis (Orthoptera: Podoscritinae)

A tree cricket,Truljalia hibinonis, is known to show a novel sperm removal during copulation. The pattern of copulations and ovipositions showed that the sperm removal functioned to increase reproductive success for sperm removing males. The sperm removal by males evolves under the system in which female accept multiple mating. The possible benefits of multiple mating for females are examined. Multiple mating did not seem to be necessary for avoiding sperm depletion, because females stored huge number of sperm in their sperm storage organ after finishing oviposition. The ingestion of metanotal secretion during copulation also had no effect on increasing fecundity and egg size. However, mating experience may have a positive effect on increasing fecundity slightly, though there were no differences between once- and twice-mated females. The other possible benefits for each male and female are discussed.     

An upstream regulator and downstream target of phospholipase D1 activity during pheromone response in Saccharomyces cerevisiae

Phospholipase D1 (PLD1), which is the product of the SPO14 gene, has been shown to play a role in the process of polarized cell growth (PCG) during the pheromone response in Saccharomyces cerevisiae. PLD1 hydrolyzes phosphatidylcholine to produce phosphatidic acid (PA) and a free choline headgroup. This study investigated the interactions of PLD1 and PA with two proteins known to be involved in the cellular signaling leading to PCG in yeast, the small GTPase Cdc42p and the PAK family kinase Ste20p. Constitutively activated Cdc42p stimulates PLD1 activity. Protein-lipid binding blots confirmed the specific binding of Ste20p to the PLD1 product, PA. Finally, kinase activity assays provided evidence for the stimulation of Ste20p by PA. These findings highlight the important interactions among PLD1, Cdc42p and Ste20p during PCG in S. cerevisiae.     

CDK and MAPK Synergistically Regulate Signaling Dynamics via a Shared Multi-site Phosphorylation Region on the Scaffold Protein Ste5

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Ontogeny of cephalic volatile patterns in queens and mating biology of the neotropical stingless bee,Scaptotrigona postica

Summary

Chemical communication is an ancient yet still immensely important part of reproduction. Amongst all invertebrates, the most sophisticated “chemical languages” are used by social insects. Here the sex- and caste-specific pheromonal messages consist of multicomponent mixtures. In the neotropical stingless bee Scaptotrigona postica, an inhabitant of dense tropical rain forests, the cephalic volatiles of a queen transmit information on her reproductive status to males. A distinct ontogenetic pattern of the queen pheromone composition allows drones to discriminate receptive virgins which are then chased during the short nuptial flight through the forest understorey. By means of gas chromatographic/mass spectroscopic analyses, the numerous volatile compounds found in pentane extracts of individual bee heads could be identified. Qualitative as well as quantitative changes of these volatiles in the course of imaginal development could be determined, and bioassays with synthetic compounds were undertaken in order to decode the chemical signals used during the short encounter of a young queen and her mate.     

ESCRT proteins and cell signalling

Subunits of the endosomal sorting complex required for transport (ESCRT) were identified as components of a molecular machinery that sorts ubiquitinated membrane proteins into the intraluminal vesicles (ILVs) of multivesicular endosomes (MVEs) for subsequent delivery to the lumen of lysosomes or related organelles. As many of the membrane proteins that undergo ESCRT-mediated sorting are signalling receptors that are ubiquitinated in response to ligand binding, ESCRT subunits have been hypothesized to play a crucial role in attenuation of cell signalling by mediating ligand-induced receptor degradation. Here we discuss this concept based on the examples from loss-of-function studies in model organisms and cell lines. The emerging picture is that ESCRTs are indeed involved in downregulation of receptor signalling pathways associated with cell survival, proliferation and polarity. In addition, the recent discovery of a positive role for the ESCRT pathway in Wnt signalling through sequestration of an inhibitory cytosolic component into MVEs illustrates that ESCRTs may also control signalling in ways that are independent of degradative receptor sorting.