The life history continuum hypothesis links traits of male ants with life outside the nest

Biological control of bruchid beetles, Callosobruchus maculatus (Fabricius) (Coleoptera: Bruchidae), infesting cowpea seeds, Vigna unguiculata (L.) Walpers (Fabaceae), can be performed via augmentative releases of Dinarmus basalis Rondani (Hymenoptera: Pteromalidae) parasitoid wasps. Females of the latter species are therefore likely to experience intense intraspecific competition: they should encounter numerous previously parasitized hosts but also conspecific competitors, with which they may fight to secure hosts on which to lay their eggs. Such contests might therefore disrupt biological control programs. Here, we studied aggressive behavior that D. basalis females show toward conspecific competitors and subsequent host exploitation strategies. We further investigated factors that classically affect contest intensity and outcomes in animals, such as the effect of ownership status, by manipulating the residency period before the intruder's arrival. In addition, we tested the effect of the size of female reproductive tissue (measured in terms of egg load) and the quality of the habitat previously experienced by females (either rich or poor in hosts). These two factors are expected to influence the value that females place on the host and therefore the costs they are willing to pay to win it. Finally, we discussed the consequences of agonistic behaviors on females' host exploitation strategies. Our results suggest that contest competition may actually enhance host control by favoring parasitoid dispersion, rather than disrupting it.     

Cytokinin‐dependent specification of the functional megaspore in the Arabidopsis female gametophyte

The life cycle of higher plants alternates between the diploid sporophytic and the haploid gametophytic phases. In angiosperms, male and female gametophytes develop within the sporophyte. During female gametophyte (FG) development, a single archesporial cell enlarges and differentiates into a megaspore mother cell, which then undergoes meiosis to give rise to four megaspores. In most species of higher plants, including Arabidopsis thaliana, the megaspore closest to the chalaza develops into the functional megaspore (FM), and the remaining three megaspores degenerate. Here, we examined the role of cytokinin signaling in FG development. We characterized the FG phenotype in three triple mutants harboring non‐overlapping T–DNA insertions in cytokinin AHK receptors. We demonstrate that even the strongest mutant is not a complete null for the cytokinin receptors. Only the strongest mutant displayed a near fully penetrant disruption of FG development, and the weakest triple ahk mutant had only a modest FG phenotype. This suggests that cytokinin signaling is essential for FG development, but that only a low threshold of signaling activity is required for this function. Furthermore, we demonstrate that there is elevated cytokinin signaling localized in the chalaza of the ovule, which is enhanced by the asymmetric localization of cytokinin biosynthetic machinery and receptors. We show that an FM‐specific marker is absent in the multiple ahk ovules, suggesting that disruption of cytokinin signaling elements in Arabidopsis blocks the FM specification. Together, this study reveals a chalazal‐localized sporophytic cytokinin signal that plays an important role in FM specification in FG development.     

Sex allocation and investment into pre- and post-copulatory traits in simultaneous hermaphrodites: the role of polyandry and local sperm competition

Sex allocation theory predicts the optimal allocation to male and female reproduction in sexual organisms. In animals, most work on sex allocation has focused on species with separate sexes and our understanding of simultaneous hermaphrodites is patchier. Recent theory predicts that sex allocation in simultaneous hermaphrodites should strongly be affected by post-copulatory sexual selection, while the role of pre-copulatory sexual selection is much less clear. Here, we review sex allocation and sexual selection theory for simultaneous hermaphrodites, and identify several strong and potentially unwarranted assumptions. We then present a model that treats allocation to sexually selected traits as components of sex allocation and explore patterns of allocation when some of these assumptions are relaxed. For example, when investment into a male sexually selected trait leads to skews in sperm competition, causing local sperm competition, this is expected to lead to a reduced allocation to sperm production. We conclude that understanding the evolution of sex allocation in simultaneous hermaphrodites requires detailed knowledge of the different sexual selection processes and their relative importance. However, little is currently known quantitatively about sexual selection in simultaneous hermaphrodites, about what the underlying traits are, and about what drives and constrains their evolution. Future work should therefore aim at quantifying sexual selection and identifying the underlying traits along the pre- to post-copulatory axis.     

马哈利樱桃大孢子发生和雌配子体的发育

采用石蜡切片法对马哈利樱桃大孢子发生和雌配子体发育过程进行观察研究。结果表明:(1)马哈利樱桃雌配子体发育早期,在单室子房内可以看到2个倒生胚珠,但在后期其中一个退化,另一个发育为种子;其胚珠具双珠被,为厚珠心。(2)大孢子母细胞减数分裂形成直线型四分体,功能大孢子位于合点端;胚囊发育为蓼型,成熟胚囊为七细胞八核。(3)根据不同时间花的外部形态特征与内部解剖学对比的观察结果,在陕西关中地区,三月下旬是马哈利樱桃雌性生殖细胞分化和发育的重要时期,果园在此期间应加强肥水管理。     

雌性哺乳动物生殖干细胞：在争议中前进

100多年以来,雌性哺乳动物出生后是否存在生殖干细胞的争议尚无定论．2004年,研究人员从出生后的小鼠卵巢中发现并分离到雌性生殖干细胞(female germline stem cells,FGSCs),挑战了存在近半个世纪的理论：哺乳动物出生后不会对卵母细胞库进行更新．随后很多研究不仅指出哺乳动物出生后卵巢中新生成的卵母细胞源自FGSCs,而且发现如果将FGSCs移植回受体卵巢,它们能够产生功能性的卵母细胞并由此得到健康的后代．可是,有的研究小组重复实验或者精心设计实验,却未得到相同的结果,甚至得出相反的结果．最近,有研究者从育龄女性卵巢中分离到了在体内外都能够分化出功能性卵母细胞的FGSCs,不过这些卵母细胞的受精能力还有待证实．本文回顾了哺乳动物FGSCs的研究历程,并对这一存在已久的争论以及FGSCs研究方向和将来的运用前景展开了评述．     

Differential regulation of cell death programs in males and females by Poly (ADP-Ribose) Polymerase-1 and 17 β estradiol

Cell death can be divided into the anti-inflammatory process of apoptosis and the pro-inflammatory process of necrosis. Necrosis, as apoptosis, is a regulated form of cell death, and Poly-(ADP-Ribose) Polymerase-1 (PARP-1) and Receptor-Interacting Protein (RIP) 1/3 are major mediators. We previously showed that absence or inhibition of PARP-1 protects mice from nephritis, however only the male mice. We therefore hypothesized that there is an inherent difference in the cell death program between the sexes. We show here that in an immune-mediated nephritis model, female mice show increased apoptosis compared to male mice. Treatment of the male mice with estrogens induced apoptosis to levels similar to that in female mice and inhibited necrosis. Although PARP-1 was activated in both male and female mice, PARP-1 inhibition reduced necrosis only in the male mice. We also show that deletion of RIP-3 did not have a sex bias. We demonstrate here that male and female mice are prone to different types of cell death. Our data also suggest that estrogens and PARP-1 are two of the mediators of the sex-bias in cell death. We therefore propose that targeting cell death based on sex will lead to tailored and better treatments for each gender.     

Der Einfluß von Vitamin A und β-Carotin auf die Fruchtbarkeit bei suboptimalen und optimalen Vitamin-B-Gaben

Die vorliegenden Untersuchungen sind Bestandteil eines komplexen Forschungsprogramms zur Weiterentwicklung der energetischen Futterbewertung im Nettoenergie‐Fett‐System. Sie wurden mit dem Ziel durchgeführt, neue Ergebnisse zur Erfassung des Zusammenhanges zwischen Ort und Art der Nährstoffverdauung und der energetischen Verwertung von Rationen bei der Tierart Rind zu erarbeiten. Für 9 Rationsvarianten mit jeweils 3 Varianten der Stärkeherkunft (Gerste, Mais, Kartoffeln) und ihres Rationsanteiles (50, 25 und 10 %) wurde an weitgehend ausgewachsenen Ochsen mit Hilfe von duodenalen Brückenfisteln auf dem Ernährungsniveau 1.7 die ruminale Nährstoffverdaulichkeit gemessen. Bei Stärkeeinnahmen zwischen 484 und 2573 g je Tier und Tag wurden Mengen an ruminai und postruminal verdauter Stärke zwischen 444 und 2336 bzw. 10 und 284 g je Tier und Tag bestimmt. Für die organische Substanz, Stärke, wasserlöslichen Kohlenhydrate und N‐freien Reststoffe wurden hohe relative Anteile der ruminai verdauten an den scheinbar verdauten Nährstoffen mit Werten zwischen 78 und 88, 83 und 98, 93 und 97 bzw. 88 und 100% ermittelt.     

Identifying MicroRNA and mRNA Expression Profiles in Embryonic Stem Cells Derived from Parthenogenetic, Androgenetic and Fertilized Blastocysts

MicroRNAs (miRNAs) are a class of highly conserved small non-coding RNA molecules that play a pivotal role in several cellular functions. In this study, miRNA and messenger RNA (mRNA) profiles were examined by Illumina microarray in mouse embryonic stem cells (ESCs) derived from parthenogenetic, androgenetic, and fertilized blastocysts. The global analysis of miRNA-mRNA target pairs provided insight into the role of miRNAs in gene expression. Results showed that a total of 125 miRNAs and 2394 mRNAs were differentially expressed between androgenetic ESCs (aESCs) and fertilized ESCs (fESCs), a total of 42 miRNAs and 87 mRNAs were differentially expressed between parthenogenetic ESCs (pESCs) and fESCs, and a total of 99 miRNAs and 1788 mRNAs were differentially expressed between aESCs and pESCs. In addition, a total of 575, 5 and 376 miRNA-mRNA target pairs were observed in aESCs vs. fESCs, pESCs vs. fESCs, and aESCs vs. pESCs, respectively. Furthermore, 15 known imprinted genes and 16 putative uniparentally expressed miRNAs with high expression levels were confirmed by both microarray and real-time RT-PCR. Finally, transfection of miRNA inhibitors was performed to validate the regulatory relationship between putative maternally expressed miRNAs and target mRNAs. Inhibition of miR-880 increased the expression of Peg3, Dyrk1b, and Prrg2 mRNA, inhibition of miR-363 increased the expression of Nfat5 and Soat1 mRNA, and inhibition of miR-883b-5p increased Nfat5, Tacstd2, and Ppapdc1 mRNA. These results warrant a functional study to fully understand the underlying regulation of genomic imprinting in early embryo development.     

外源激素对马尾松花芽分化及内源物质的影响

为探讨马尾松球花形成与植物激素水平的关系,该研究对贵州省都匀无性系种子园11年生马尾松进行不同浓度的 IAA、IBA、GA3、BAP等植物激素处理,采用考马斯亮蓝G-250染色法、蒽酮法分别对不同浓度不同激素处理后的枝条上针叶中的可溶性蛋白质和可溶性糖含量变化进行测定,并在第二年开花时对试验枝条的开花情况进行了调查。结果表明：在8－11月份,进行500 mg·L-1的BAP 处理有利于马尾松雌球花和雄球花的形成,100 mg·L-1的GA3处理有利于马尾松雌球花的形成;而GA3250 mg·L-1和GA3500 mg·L-1处理有利于马尾松雄球花的形成,IAA 250 mg·L-1对马尾松雌雄球花同枝的数量有提高作用。在10－11月份,对马尾松进行500 mg·L-1的BAP、IAA、GA3处理后,马尾松针叶内蛋白质含量变化有显著影响;在10月份时,进行BAP 100 mg·L-1处理后,其可溶性糖含量及可溶性蛋白含量均可达到极显著水平。而在8月份与10月份时,分别进行IBA 100 mg·L-1与IBA 250 mg·L-1处理后,其可溶性蛋白含量与其对照差异处于极显著水平;在11月份时,进行GA3100 mg·L-1处理后,其可溶性蛋白含量与其对照差异处于极显著水平;而在11月份时,进行IBA 500 mg·L-1处理后,其可溶性蛋白含量与对照差异处于显著水平。     

Early constraints in sexual dimorphism: survival benefits of feminized phenotypes

Sexual dimorphism (SD) has evolved in response to selection pressures that differ between sexes. Since such pressures change across an individual's life, SD may vary within age classes. Yet, little is known about how selection on early phenotypes may drive the final SD observed in adults. In many dimorphic species, juveniles resemble adult females rather than adult males, meaning that out of the selective pressures established by sexual selection feminized phenotypes may be adaptive. If true, fitness benefits of early female‐like phenotypes may constrain the expression of male phenotypes in adulthood. Using the common kestrel Falco tinnunculus as a study model, we evaluated the fitness advantages of expressing more feminized phenotypes at youth. Although more similar to adult females than to adult males, common kestrel fledglings are still sexually dimorphic in size and coloration. Integrating morphological and chromatic variables, we analysed the phenotypic divergence between sexes as a measure of how much each individual looks like the sex to which it belongs (phenotypic sexual resemblance, PSR). We then tested the fitness benefits associated with PSR by means of the probability of recruitment in the population. We found a significant interaction between PSR and sex, showing that in both sexes more feminized phenotypes recruited more into the population than less feminized phenotypes. Moreover, males showed lower PSR than females and a higher proportion of incorrect sex classifications. These findings suggest that the mechanisms in males devoted to resembling female phenotypes in youth, due to a trend to increase fitness through more feminized phenotypes, may provide a mechanism to constrain the SD in adulthood.