短额负蝗与中华蚱蜢精子比较：直翅目：蝗总科

短额负蝗与中华蚱蜢精子比较（直翅目：蝗总科）奚耕思,郑哲民（陕西师范大学动物研究所陕西省西安市７１００６２）短额负蝗Ａｔｒａｃｔｏｍｏｒｐｈａｓｉｎｅｎｓｉｓ与中华蚱蜢Ａｃｒｉｄａｃｉｎｅｒｅａ为中国两种常见的蝗虫。由于头顶细纵沟,后足股节外侧花纹及...     

Sperm morphology in five species of cicadettine cicadas (Hemiptera: Cicadomorpha: Cicadidae)

Mature spermatozoa from five species of cicadas of the subfamily Cicadettinae (Quintilia wealei, Melampsalta leucoptera, Stagira simplex, Xosopsaltria thunbergi and Monomatapa matoposa) were examined by light and electron microscopy. In each species sperm are elongate, aggregated into organized bundles with their heads embedded in a homogenous matrix to form spermatodesmata, and exhibit polymegaly. The head of the sperm consist of an anteriorly positioned conical acrosome that has a tubular substructure and a deep, posterior invagination that forms the subacrosomal space (eccentrically positioned anteriorly). The acrosome is flattened anteriorly; posteriorly it extends along either side of the nucleus as two tubular processes that gradually decrease in diameter. The filiform nucleus tapers anteriorly and intrudes into the subscrosomal space. Posteriorly the nucleus has a lateral invagination that houses material of the so-called centriolar adjunct. Posterior to the centriolar adjuct and the nucleus are two crystalline mitochondrial derivatives and a centriole, respectively, the latter giving rise to the axoneme, which has a 9 + 9 + 2 arrangement of microtubules. In these respects the sperm are similar to those of platypleurine cicadas. However, some features seem unique to cicadettines, including the structural organization of an enlarged centriolar adjunct and the dimensions of the tails. The enlarged centriolar adjunct has a lamella-like substructure and can be considered a synapomorphic character in the Cicadettinae. It is, therefore, potentially useful in the separation of this subfamily from the Cicadinae. In addition, the great length of the sperm nucleus of long-headed sperm in M. matoposa could be a synapomorphy of this genus and related taphurine and cicadettine species.     

四种癞蝗精子的比较研究（直翅目：蝗总科）

本文通过对丽突鼻蝗ＲｈｉｎｏｔｍｅｔｈｉｓｐｕｌｃｈｒｉｓＸｉｅｔＺｈｅｎｇ、景泰突颜蝗ＥｏｔｍｅｔｈｉｓｊｉｎｔａｉｅｎｓｉｓＸｉｅｔＺｈｅｎｇ、友谊华癞蝗ＳｉｎｏｔｍｅｔｈｉｓａｍｉｃｕｓＢ．－Ｂｉｅｎｋｏｔ和短翅华癞蝗ＳｉｎｏｔｍｅｔｈｉｓｂｒａｃｈｙｐｔｅｒｕｓＺｈｅｎｇｅｔＸｉ精子的比较研究,发现它们的精子的线粒体衍生体超微形态结构及精子发生过程中第７、８两期精细胞线粒体衍生体周围微管排数十分相似,而在精子的外形长度、中心粒侧体超微形态结构及线粒体衍生体的大小等项特征方面存在着一定差异,这些差异只是在种间精子的鉴别方面有一定的意义,而不具有属级水平的鉴别意义。     

两种网翅蝗精子的比较研究：直翅目：蝗总科

通过对青脊竹蝗Ｃｅｒａｃｒｉｓ ｎｉｇｇｒｉｃｏｒｎｉｓ ｎｉｇｒｉｃｏｒｎｉｓ Ｗａｌｋ及宽翅曲背蚯 Ｐａｒａｒｃｙｐｔｅｒａ ｍｉｃｒｏｐｔｅｒａ ｍｅｒｉｄｉｏｎａｌｉｓ 精子的比较。发它们的精子的线粒体衍生体和中心粒 本的超微形态结构以及精子发生过程中七,八两期精 细胞线粒体衍生体周围微的排数十分相似。     

斑腿蝗科三个种类精子的比较研究：直翅目：蝗总科

本文通过对日本黄脊蝗Ｐａｔａｎｇａｊａｐｏｉｎｃａ（Ｉ．Ｂｄ）,短角直斑腿蝗ＳｔｅｎｏｃａｔａｎｔｏｐｓｍｉｓｔｓｈｅｎｋｏｉＷｉｌｌ和霍山蹦蝗ＳｉｎｏｐｏｄｉｓｍａｈｏｕｓｈａｎａＨｕａｎｇ精子的比较,发现了它们的精子的线粒体衍生体和中心粒侧体的超微形态结构十分相似,在精子发生过程中７、８两期精细胞线粒体衍生体周围微管的排数相一致,这３个种精子间的差异主要反映在外形头和尾的长度,线粒体衍生体的大     

Sperm tail differentiation in the nudibranch mollusc Hypselodoris tricolor (gastropoda,opisthobranchia)

The sperm axoneme of Hypselodoris tricolor forms from a single centriole that is located initially beneath the plasma membrane and then migrates to the nuclear surface. A conspicuous centriolar adjunct-like formation is present in the neck of midspermatids, but it becomes very reduced at the end of spermiogenesis. In spermatocyte and spermatid mitochondria, intracristal bodies originate from the accumulation of a dense material in some cristae. From our observations and foregoing reports, it may be concluded that the process of sperm tail differentiation in opisthobranchs resembles that in pulmonates, whereas it differs in many respects from that occurring in prosobranchs. The appearance of intracristal bodies in modified mitochondria seems to be a special feature of spermatogenesis in the opisthobranchs that does not occur in the two other groups of gastropod molluscs.     

The ultrastructure of the spermatozoa of Boa constrictor occidentalis, with considerations on its mating system and sperm competition theories

Sperm ultrastructure has been described for several families of Squamata in which it has been considered a valuable character source for phylogenetic studies. However, sperm competition and mating systems have been demonstrated to influence variations in the sperm morphology and dynamics. The mating system of Boa constrictor occidentalis is likely to have a high degree of sperm competition. We investigated, for the first time, the ultrastructure of the spermatozoa of B. c. occidentalis and, thus, of the family Boidae. Active mating groups were captured from the field, and the spermatozoa of the males was collected by ejaculation and processed to obtain transmission electron micrographs and fluorescence micrographs. The spermatozoa are filiform and their morphology fits the general model described for snakes, and several synapomorphies belonging to the squamates can be identified in these cells. Nevertheless, the head is 25% longer and the midpiece presents a lower frequency of mitochondrial transformations than that of other snakes. We propose that this last trait, along with the extraordinary elongation of the midpiece and the system of multilaminar membranes covering this section (both synapomorphies of the snake spermatozoa), are adaptive responses to processes of sperm competition and sperm storage.     

Spermiogenesis in three species of cicadas (Hemiptera: Cicadidae)

Spermiogenesis in three species of cicadas representing one cicadettine (Monomatapa matoposa Boulard) and two cicadines (Diceroprocta biconica [Walker] and Kongota punctigera [Walker]) was investigated by light and electron microscopy. Although spermiogenesis was occurring in the testis of adult males of all species, earlier spermiogenic stages were observed in D. biconica only. While spermiogenesis was similar to that described for other insects, some differences were noted. For example granular material did not assemble around the centriole to form a centriolar adjunct but did accumulate in the cytoplasm of early spermatids adjacent to a region of the nuclear membrane where nuclear pores were aggregated. In late spermatids this material accumulated anterior to the mitochondrial derivatives in a developing postero‐lateral nuclear groove. While this material has been named the ‘centriolar adjunct’ by previous authors, its formation away from the centriole raises questions about its true identity. Second, during acrosome maturation an ante‐acrosomal region of cytoplasm develops. Although present in later spermatids, this region is lost in spermatozoa. Interspecific variations in chromatin condensation patterns and the number of microtubule layers encircling the spermatid nucleus during spermiogenesis were noted.     

Sperm competition mechanisms in birds: models and data

This study presents three models to explain the mechanism oflast male sperm precedence in birds. Because passive loss ofsperm from the female reproductive tract occurs, all modelsincorporate this process. The three models are passive spermloss alone, stratification with passive sperm loss, and displacementwith passive sperm loss. With two inseminations containing thesame number of sperm, the models make the following predictions.For passive sperm loss alone, (1) differential paternity ispositively and linearly related to the time interval betweeninseminations, (2) with a slope that is equal to rate of lossof sperm from the female reproductive tract, (3) with an interceptthat is the same as the differential fertilizing capacity betweenthe semen of the two inseminations, and (4) the ratio of offspringfrom two inseminations remains constant over time. For stratification,(1) the relationship between differential paternity and theinterval between inseminations is nonlinear and exhibits a "brokenstick" pattern, with a substantial first-insemination precedencefor short intervals, and (2) the proportion of offspring fatheredby the first insemination increases over time. For displacement,the relationship between differential paternity and the intervalbetween inseminations is nonlinear and also exhibits a "brokenstick" pattern, but in contrast to the stratification model,sperm from the last insemination have precedence. Data fromthree experimental studies of the domestic fowl and one forthe turkey provide the opportunity to test these models, albeitto different extents. The data from all studies are consistentwith the passive sperm-loss model, except that one aspect ofone data set provided ambiguous support for stratification.None of the data provided any support for the displacement model.     

An ultrastructural analysis of mature sperm from the crayfish Pacifastacus leniusculus,Dana

Sperm from the crayfish, Pacifastacus leniusculus, resemble other reptantian sperm in that they are composed of an acrosome, subacrosomal region, nucleus, membrane lamellar complex, and spikes which radiate from the nuclear compartment. The acrosome (PAS positive vesicle) can be subdivided into three regions: the apical cap, crystalline inner acrosomal material, and outer acrosomal material which is homogeneous except for a peripheral electron dense band. The nucleus contains uncondensed chromatin and bundles of microtubules which project into the spikes. The orientation of the microtubule bundles relative to the nuclear envelope near the base of the subacrosomal region suggests that the nuclear envelope may function in the organization of the spike microtubules.     

Sperm competition games: the risk model can generate higher sperm allocation to virgin females

We examine the risk model in sperm competition games for cases where female fertility increases significantly with sperm numbers (sperm limitation). Without sperm competition, sperm allocation increases with sperm limitation. We define 'average risk' as the probability q that females in the population mate twice, and 'perceived risk' as the information males gain about the sperm competition probability with individual females. If males obtain no information from individual females, sperm numbers increase with q unless sperm limitation is high and one of the two competing ejaculates is strongly disfavoured. If males can distinguish between virgin and mated females, greater sperm allocation to virgins is favoured by high sperm limitation, high q, and by the second male's ejaculate being disfavoured. With high sperm limitation, sperm allocation to virgins increases and to mated females decreases with q at high q levels. With perfect information about female mating pattern, sperm allocation (i) to virgins that will mate again exceeds that to mated females and to virgins that will mate only once, (ii) to virgins that mate only once exceeds that for mated females if q is high and there is high second male disadvantage and (iii) to each type of female can decrease with q if sperm limitation is high, although the average allocation increases at least across low q levels. In general, higher sperm allocation to virgins is favoured by: strong disadvantage to the second ejaculate, high sperm limitation, high average risk and increased information (perceived risk). These conditions may apply in a few species, especially spiders.     

The short spermatodesm of Arge pagana (Hymenoptera: symphyta)

In the seminal vesicle of the 'symphyta'Arge pagana the spermatozoa are stored in motile spermatodesm bundles, maintained by an anterior cap of extracellular material. This cap consists of a denser cortex and of an internal matrix, where part of the sperm heads are embedded. The number of spermatozoa per bundle is variable. The spermatozoa are short, only 30microm long, with a head region of about 23microm, and a very short flagellum of about 7microm. The head includes the acrosome, with a perforatorium, and the nucleus. The flagellum consists of an axoneme, with a 9+9+2 microtubule pattern, a centriolar adjunct, two mitochondrial derivatives and two accessory bodies. The mitochondrial derivatives are very slender and of different lengths. The longer begins at the base of the nucleus, while the shorter one starts just below the base of the centriolar adjunct. This latter is asymmetric and appears at the nuclear base, extending parallel to the axoneme up to the anterior end of the smaller mitochondrial derivative. The short spermatodesmata and the small mitochondrial derivatives characterize the A. pagana sperm. In addition, the centriolar adjunct asymmetry and the occurrence of spermatodesm bundles might be considered plesiomorphic states present in the basal Tenthredinoidea.     

长吻鮠精子超微结构的观察

用透射电镜和扫描电镜观察了长吻（ＬｅｉｏｃａｓｓｉｓｌｏｎｇｉｒｏｓｔｒｉｓＧｕｎｔｈｅｒ）精子的超微结构。长吻精子具有椭圆的头部和复杂的中片;近侧中心粒和远侧中心粒靠近核的中央;鞭毛呈９＋２轴丝结构,并具有由外膜折迭形成的波浪形的鳍状结构。研究表明,长吻精子具有某些区别于其它鱼类精子的不同结构。     

Ultrastructure of Sperm in <Emphasis Type="Italic">Mercenaria stimpsoni</Emphasis> and <Emphasis Type="Italic">Mactra chinensis</Emphasis> (Mollusca: Bivalvia) from the Sea of Japan

The ultrastructure of the sperm of the common bivalve species Mercenaria stimpsoni and Mactra chinensis from Peter the Great Bay is described. The sperm structure is typical for animals with external insemination. The sperm consists of a head, middle part, and flagellum. The sperm head of M. stimpsoni has a curved crescent form and includes the nucleus and acrosome; the head length is 9.8 μm. The acrosome is subdivided to the acrosome granule and the periacrosomal material. There are 4 mitochondria of about 0.8 μm in size in the middle part of the spermatozoon. The mitochondria surround the centriolar apparatus, which consists of proximal and distal centrioles located at a right angle. The axoneme originates from the distal centriole. The sperm of M. chinensis is barrel-shaped, with a head length of 3.2 μm. The acrosome is relatively larger, and its height is 1–1.2 μm. There are also 4 mitochondria 0.6–0.8 μm in the middle part of the spermatozoon. The sperm structure of the described species is typical of the families to which the mollusks belong, with insignificant variations.     

Pitfalls in experiments testing predictions from sperm competition theory

As females of many species mate with more than one male, ejaculates often face competition from the sperm of other males. In recent years, numerous papers have been published on theoretical predictions of evolutionary, behavioural and physiological responses to variation in the strength of sperm competition (SC). These theoretical predictions have also been extensively tested. However, although predictions from SC theory are relatively straightforward, extra caution has to be paid in the design of experiments testing them. One difficulty is for example to disentangle immediate and mean SC risk and intensity. Without carefully designed experiments, it is also very easy to simultaneously increase SC risk and the probability of intense SC--a situation for which we currently have no clear predictions, as the theoretical models to date only assume variation in either SC risk or intensity. In this paper, we discuss these and some other pitfalls related to manipulations of SC risk and intensity and suggest how to avoid them.