GABA neurones in retinas of different species and their postnatal development in situ and in culture in the rabbit retina

Summary The localisation of GABA immunoreactive neurones in retinas of a variety of animals was examined. Immunoreactivity was associated with specific populations of amacrine neurones in all species examined, viz. rat, rabbit, goldfish, frog, pigeon and guinea-pig. All species, with the exception of the frog, possessed immunoreactive perikarya in their retinal ganglion cell layers. These perikarya are probably displaced amacrine cells because GABA immunoreactivity was absent from the optic nerves and destruction of the rat optic nerve did not result in degeneration of these cells. GABA immunoreactivity was also associated with the outer plexiform layers of all the retinas studied; these processes are derived from GABA-positive horizontal cells in rat, rabbit, frog, pigeon and goldfish retinas, from bipolar-like cells in the frog, and probably from interplexiform cells in the guinea-pig retina.The development of GABA-positive neurones in the rabbit retina was also analysed. Immunoreactivity was clearly associated with subpopulations of amacrine and horizontal cells on the second postnatal day. The immunoreactivity at this stage is strong, and fairly well developed processes are apparent. The intensity of the immunoreactivity increases with development in the case of the amacrine cells. The immunoreactive neurones appear fully developed at about the 8th postnatal day, although the immunoreactivity in the inner plexiform layer becomes more dispersed as development proceeds. The immunoreactive horizontal cells become less apparent as development proceeds, but they can still be seen in the adult retina.The GABA immunoreactive cells in rabbit retinas can be maintained in culture. Cultures of retinal cells derived from 2-day-old animals can be maintained for up to 20 days and show the presence of GABA-positive cells at all stages. In one-day-old cultures the GABA immunoreactive cells lacked processes but within three days had clearly defined processes. After maintenance for 10 days a meshwork of GABA-positive fibres could also be seen in the cultures.     

绕茧蜂属寄生于云杉四眼小蠹成虫的—新种记述并附本属世界种检索表(膜翅目:茧蜂科)

绕茧蜂属Ropalophorus Curtis,1837是茧蜂科中的一个小属,迄今世界上仅记载有2种。一种为R.clavicornis(Wesmael),1835,分布于欧州及日本,寄生于云杉八齿小蠹Ips typographus及I.amitinus成虫体内;另一种为R.wisconsinensis Shenefelt,1960,仅分布于美国,由于该种是用诱捕器捕到的,因此,其奇主不详,但有可能为I.pini(Shenefelt,1960)。     

Behavioral response of 12 ungulate species in captivity to the presence of humans

Twelve species of captive ungulates were studied to determine behavioral responses to the presence of a zookeeper within the exhibit and in front of the exhibit, with and without zoo visitors present. Significant differences in behavior occurred between species for nearly all behaviors observed. A significantly greater occurrence of vigilance and approach behavior was directed toward the zookeeper while within the exhibit relative to when the zookeeper stood in front of the exhibit. A significantly lower occurrence of eating or drinking occurred when the zookeeper was inside the exhibit. Significant differences occurred across size categories in the occurrence of approaching the zookeeper. The most frequently scored behavior was visual orientation. Statistically significant differences in the occurrence of visual orientation directed by females toward the zookeeper existed across size category, with more vigilance by species with larger body size. A statistically higher occurrence of vigilance toward the zookeeper was directed by female ungulates but not by males when the zoo was closed to the public. Although no statistical significance was found regarding the intraspecific vigilance of males, data on females revealed significant differences across species and across size categories. When data regarding vigilance toward the public were analyzed, statistically significant differences existed between species for females only. Likewise, when data regarding interspecific vigilance were examined, statistically significant differences were found across size categories for females, but not for males. The potential roles of vigilance in the wild are discussed in reference to its role in captivity.     

Isozyme differentiation among sibling species and among populations of the Echinogammarus berilloni-group (Crustacea, Amphipoda)

The sibling species of the Echinogammarus berilloni-group are endemic for the Iberian Peninsula and southern France. These species show wide morphological variability with some overlap in their dianostic characters making their distinction difficult. Reroductive isolation and enzmatic jivergence amon allopatric and sympatric populations of four species sharing the same chromosome number has been studied. The results show a clear genetic differentiation of E. longiserosus and E. calvus versus the other two species. However, E. margalefi and E. echinosetosus show no clear genetic differentiation between them, confirming their crose relationship. All four species often coexist in the same drainage system. Isozme analysis was employed to check the hypothesis Of Margalef that sympathy would occur age, long-term phenomena of speciation inside of a given basin with subsequent contact and overlap between the differentiated forms. Electrophoretic data were also used to determine whether one flow among gammarids populations exists. A model proosed by other authors according to which the heterozyosity decreases towards the headwaters foes not fit to the data we have obtained from E. calvus. Thus, populations of this species from sources and springs of the Duero basin show the hiFhest values of mean heterozygosity. The differentiation in this basin can be explained by drift. Migration between populations of different rivers is prevented by natural barriers. The lowest river stretches are without amhipods interrupting the gene flow amon populations. A correction between genetic and geographic fistances among subbasins and basins was found applying a double logarithmic model. A model of migration of E. calvus in the Duero basin is proposed on the basis of allelic frequencies and on the distribution of mean hetero-zygosities.     

Conservatism of sites of tRNA loci among the linkage groups of severalDrosophila species

Summary The sites of seven tRNA genes (Arg-2, Lys-2, Ser-2b, Ser-7, Thr-3, Thr-4, Val-3b) were studied by in situ hybridization.¹²⁵I-labeled tRNA probes fromDrosophila melanogaster were hybridized to spreads of polytene chromosomes prepared from fourDrosophila species representing different evolutionary lineages (D. melanogaster, Drosophila hydei, Drosophila pseudoobscura, andDrosophila virilis). Most tRNA loci occurred on homologous chromosomal elements of all four species. In some cases the number of hybridization sites within an element varied and sites on nonhomologous elements were found. It was observed that both tRNA ₂ ^Arg and tRNA ₂ ^Lys hybridized to the same site on homologous elements in several species. These data suggest a limited amount of exchange among different linkage groups during the evolution ofDrosophila species.     

Ocean current variability and the spawning season of Hawaiian reef fishes

Synopsis The spawning patterns of four Hawaiian reef fishes with similar reproductive habits, but different biogeographic distributions were studied from September 1980 to October 1981. Two species are Hawaiian endemics [Centropyge potteri (Pomacanthidae) and Chaetodon multicinctus (Chaetodontidae)] and the other two have pan-tropical Pacific distributions [Ctenochaetus strigosus and Zebrasoma flavescens (Acanthuridae)]. All showed increased spawning activity from January to July, the prevalent pattern among a majority of coastal marine fishes in Hawaii. Environmental correlatives to the period of peak reproduction include cycles of (a) daylight length and temperature which probably function as proximate cues and (b) seasonal variations in ocean current patterns which may ultimately affect survival of larvae and dispersal. Peak reproduction takes place during months when (1) mesoscale eddies most likely occur, and (2) the probability is greatest of drifting objects remaining near the islands.     

The habitat diversity and fish reproductive function of floodplain ecosystems

Synopsis Fish reproduction in floodplain ecosystems, based on relative abundance and total biomass of 0+ juveniles, was studied using the synchronic approach to typological analysis in conjunction with Point Abundance Sampling by modified electrofishing. In 3 different flood plains of the Upper Rhône River, 1015 point samples yielding 4573 juveniles (0+) from 21 species were collected from 48 ecosystems of various geomorphological origin. The results demonstrate the lotic-to-lentic succession of floodplain ecosystems to be a series of non-sequential reproductive zones, with spawning conditions being reflected by the specific composition and guild structure of the YOY fish assemblages. The habitat diversity and the fish reproductive potential of floodplain ecosystems are strongly influenced by geomorphological origin and by past and present hydrological conditions. The YOY assemblages of autogenically driven ecosystems (usually of anastomose or meander origin) tend to differ both in composition and in quantity from those found in allogenically driven ecosystems (generally of braided origin). Ecosystems of intermediate character, and fish reproduction thereof, occur as the result of either ecosystem rejuvenation or senescence: autogenically driven ecosystems by allogenic mechanisms, or allogenically driven ecosystems by anthropic and/or autogenic mechanisms, respectively. Because of co-occurrence of ecosystems at similar and at different successional status, the flood plain as an entity is seen as stable with respect to fish reproduction.     

云南西部狭臀蚤属四新种记述：蚤目：多毛蚤科

本文报告云南西部狭臀蚤属Steni(?)chia 4新种:1)金氏狭臀蚤,新种 S.chini sp.nov.与锐额狭臀蚤 S.angustifrontalis Xie et Gong接近;2)李氏狭臀蚤,新种 S.liae sp.nov.与金氏狭臀蚤新种和锐额狭臀蚤接近;3)柳氏狭臀蚤,新种 S.liui sp.nov.与李氏狭臀蚤新种和高山狭臀蚤S.montanis xie et Gong接近。4)吴氏狭臀蚤,新种 S.wui sp.nov.与卢氏狭臀蚤 S.lewis Smit接近。本文认论了李氏狭臀蚤新种与金氏狭臀蚤新种的形态分类及本属蚤类的宿主等生态问題,并编制本属14种的检索表。     

珠恙螨属一新种：真螨目：恙螨科

本文描述1个珠恙螨属 Doloisia一新种,采自广东省罗定县社鼠 Rattus confucianus 鼻内,其感器双角状,盾板后侧毛的分枝长密,前侧毛光裸;足指数795。