摘要:

Migrating primordial germ cells ofRana dalmatinaembryos were labelled byDolichos biflorusagglutinin. Confocal microscopy analysis demonstrates the nuclear localisation of the labelling. The glycoconjugate is expressed by primordial germ cells throughout the entire migration process, but it is no longer detectable in late intragonadal primordial germ cells. These data suggest that the a‐N‐acetylgalactosamine‐containing glycoconju‐gates in the nucleus of primordial germ cells may play a functional role in primordial germ cells protection against differentiation during the migration process. The temporal correlation between disappearance of nuclearDolichos biflorusagglutinin positivity and colonisation of the gonadal ridges, may be explained by a change in the functional status of primordial germ cells nuclear glycoconjugates in relation with the onset of primordial germ cells differentiation.

ISSN:1125-0003    

DOI:10.1080/11250008809386754

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The morphological comparison of the facial skeleton and tongue between young nestlings and subadults has shown thatMeropsdesmognatism is due to the ossification of theprocessus prenasalisandsolum nasi.The maxillo‐palatines are not fused along the midline and the pterigoid is fused to the vomer. The heterochrony in the development of the skull ofMeropswas suggested to be due to protracted parental care so that only when the bird captures its prey, do the stresses produced in the killing actions induce ossification of thesolum nasiand of theprocessus prenasalis.

ISSN:1125-0003    

DOI:10.1080/11250008809386755

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The lactate dehydrogenase activity was examined in skeletal muscles of specimens of 53 species of Orthoptera belonging to five families of Ensifera and four of Caelifera. The results showed that: (1) the five families of Ensifera contain a low level of lactate dehydrogenase activity in their jumping muscles, whereas two families of Caelifera, Catantopidae and Acrididae, contain a far higher level; (2) in the four families of Caelifera, there are two well‐distinct levels of activity of lactate dehydrogenase in leg muscles, and (3) the lactate dehydrogenase activity in the jumping femurs is, in general, more than double that of the non‐jumping femurs. It was suggested that this difference in activity between specialized and non‐specialized leg segments represents a metabolic adaptation to burst muscular activity.

ISSN:1125-0003    

DOI:10.1080/11250008809386756

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The gypsy mothLymantria dispar,like many other forest defoliator species, exhibits periodic population outbreak dynamics, whose variability in different years and in different places can be attributed to different microclimatic parameters. This study was focused on the correlation between climatic variations in two different localities of Sardinia over a three‐year period and on changes in sensitivity of the male antennal olfactory receptors. Our electrophysiological results show that olfactory EAG responses to the sex pheromone of the antennae are inversely correlated with rainfall during gypsy moth larval development. On the other hand, male antennal sensitivity and ambient temperature were not correlated, possibly due to the fact that no significant climatic variations were detected in the period examined. Our findings, especially for rainfall, are in good agreement with data in the literature concerning the effects of weather on gypsy moth population dynamics.

ISSN:1125-0003    

DOI:10.1080/11250008809386757

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

An adult maleRattus norvegicns,with a greyish‐brown sandy colour, similar to the mutantbrownassociated with the normalagouti’allele, was trapped near Pavia in the year 1958. In 1960 we started a line by crossing this unusual animal with an albino female. After several years (in 1987), the progeny of these crosses produced a female affected by motor disorder corresponding to the description of the mutantwaltzer.The close correspondence of the observed phenotypes withbrownandwaltzersuggest alle‐lism between the mutants responsible; however a direct test to confirm allelism was unfeasible. The origin of the mutants, their observed phenotypic properties and inheritance and, with regard towaltzer,degree of penetrance, are here reported.

ISSN:1125-0003    

DOI:10.1080/11250008809386758

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Nuclei of amphibian oocytes contain spheres, either attached at specific loci of lampbrush chromosomes or free in the nucleo‐plasm, the structure and function of which have been investigated for long time. These spheres were initially shown to contain components involved in pre‐mRNA splicing, pre‐rRNA processing and histone pre‐mRNA 3’ end formation. Later, the spheres were labelled by B24/3monoclonal antibody, which recognizes a maternal protein of 104 kDa. Recently, a cDNA clone encoding protein B24has been isolated inTriturus carnifexand analysis of the nu‐cleotide sequence has shown that B24protein belongs to the Mcm/P1 family, which is thought to play an important and conserved role in initiation of DNA replication. To test the function of B24protein microinjections of B24/3mAb were made into one blastomere of two and four‐cell stage embryos. The injected cell degenerated and only hemi‐embryos or underdeveloped embryos were obtained, because B24protein plays an important role in cell division during early development. The results show that the spheres appear as complex accumulation sites of several maternal factors.

ISSN:1125-0003    

DOI:10.1080/11250008809386759

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Hypervariable minisatellite markers have widely been used in forensic, paternity, and mating system studies, and applied to population genetics of animals and plants. In birds, minisatellite DNA fingerprinting was first developed through the use of 33.15 and 33.6 poly‐core probes. To date, few studies exist where other fingerprinting probes have been used. The aim of the present analysis is to extend the use of the M13 minisatellite probe to the genetic study of natural populations of passerine and non‐passerine birds through the optimization of an easy‐to‐make procedure, in order to address questions related with the biogeography, ecology, reproductive biology, and systematics of this group. The M13 fingerprinting probe yielded multibanded fingerprints from the genomes of all species analysed, and the average number of bands was comparable with values obtained in literature using different multilocus probes. Similarity values varied according to the phylogenetic distances among taxonomic units. InPasser montanus,the analysed populations proved to be genetically distinct, and the within‐population similarity values were comparable with those obtained, using the same technique, in a congeneric species.

ISSN:1125-0003    

DOI:10.1080/11250008809386760

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Populations ofZootoca viviparaappear karyologically well differentiated by heterochromatin distribution both in autosomes and sex‐chromosomes; allopatric oviparous populations possess few elements with centromeric heterochromatin and W acrocen‐tric sex‐chromosomes with heterochromatin only on the centromere; Alpine, as well as central‐western European viviparous populations possess conspicuous centromeric bands of heterochromatin on all of the chromosome pairs and a metacentric W chromosome with paracentromeric and telomeric heterochromatin bands; viviparous populations, living east and possibly north of the Carpathian Mountains, have many elements with interstitial and telomeric heterochromatin and an acrocentric W chromosome with telomeric and subtelomeric heterochroma. These data suggest an origin and evolution of sex‐chromosomes in this species, that, interestingly, parallels the recent hypothesis (Heulinet al.,1993) on the rise and evolution of viviparity and speciation inZootoca.

ISSN:1125-0003    

DOI:10.1080/11250008809386761

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Cellulose acetate electrophoresis of allozymes was used to differentiate the two endangered Mediterranean killifishes,Aphanius iberusandA. fasciatus.Thirty‐eight putative enzyme‐coding loci were examined in two populations from the Albuixec lagoon (Spain) and from the Biguglia coastal pond (Corsica). Low within‐population polymorphism was detected. The mean number of al‐leles per locus, percentage of polymorphic loci, and heterozygos‐ity were A = 1.2 (SE 0.1), P99= 21.1%, H = 0.050 (SE 0.018) inA. iberus,and A = 1.3 (SE 0.1), P99= 28.9%, H = 0.057 (SE 0.019) inA. fasciatus.A general concordance with the Hardy‐Weinberg equilibrium was detected. Allelic distribution for 13 loci proved diagnostic at species level. The genetic distance between the two species analysed was relatively high (D = 0.539), indicating considerable genetic divergence between the two congeneric species. These results represent a valuable basis for further studies on the genetic structure of Mediterranean cyprinodontids to ensure sustainable management of these species.

ISSN:1125-0003    

DOI:10.1080/11250008809386762

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The status and the ecological correlates of occurrence of the leopard (Panthera pardusLinnaeus, 1758) from rainforests of southeastern Nigeria are presented in this paper. A total of 47 randomly selected forest patches with at least some patches of primary vegetation were examined, and eight different environmental variables were recorded from each study site. Canonical Analysis and Principal Component Analysis were used toassesswhich variables were positively correlated with the presence of the leopards, which proved extremely rare over the whole study region. In fact, the presence of the leopard was ascertained only in two sites (4.25% of the total number of surveyed areas), whereas it was a possibility in four other sites (8.5% of the total number of surveyed areas). Scats and tracks were found in only one of the former localities, whereas the skull of a recently killed adult specimen was seen in the other of the two sites. The various environmental parameters include total wooded surface (TWS), linear distance from the closest creek or pond (LDW), and the presence of some potential prey types (Cercopithecusmonkeys; PM, andCephalophusantelopes, PA). Some conservation implications of the observed patterns are also discussed.

ISSN:1125-0003    

DOI:10.1080/11250008809386763

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor