Studien über die Morphologie der Chromosomen des Myrmus miriformis

Ohne Zusammenfassung     

Molecular taxonomy and phylogeny of the Geodiidae (Porifera, Demospongiae, Astrophorida) – combining phylogenetic and Linnaean classification

Cárdenas, P., Rapp, H. T., Schander, C. & Tendal, O. S. (2009). Molecular taxonomy and phylogeny of the Geodiidae (Porifera, Demospongiae, Astrophorida) – combining phylogenetic and Linnaean classification.—Zoologica Scripta, 39, 89–106. According to the fossil records, the Geodiidae represents one of the oldest families of demosponges (Phylum Porifera). There are approximately 220 described extant species, geographically and bathymetrically widely distributed around the world. Species of this family all share a two-layered cortex with ball-shaped spicules called ‘sterrasters’ in the endocortex. However, molecular studies have questioned the monophyly of the group. Moreover, the evolutionary history and the intrafamily relationships of the Geodiidae are not fully resolved. Using a partial sequence of the cytochrome c oxidase subunit 1 (COI) gene and a partial sequence of the 28S rDNA gene (D1–D2 domains), we present the first molecular phylogeny focusing on this group. The congruent results from the two gene fragments suggest that (i) the Geodiidae is monophyletic, (ii) the Erylinae/Geodinae subdivision sensu Sollas, 1888 is valid and that (iii) Isops and Sidonops are junior synonyms of Geodia. The synonymization of Isops and Sidonops implies that the oscule/pore morphology as a diagnostic character should be abandoned. Geodia hentscheli nom. nov. has been given for Geodia mesotriaena ( Hentschel, 1929 ). This study served as the basis for a revised phylogenetic classification of the Geodiidae. Well-supported clades led to the establishment of clade names following the PhyloCode. The Geodinae clade is strongly supported and notably composed of Depressiogeodia, Cydonium and Geodia. A morphological synapomorphy of Geodinae is the presence of euasters in the ectocortex. The Erylinae (Erylus, Penares, Caminus and Pachymatisma) form a strongly supported monophyletic group with three morphological synapomorphies: (i) loss of anatriaenes and protriaenes, (ii) microrhabds (or spherules) in the ectocortex and (iii) short-shafted triaenes. The Erylus monophyly is ambiguous. Erylus species are distributed in three well-supported clades. Finally, spicule homology in the cortex of the Geodiidae is discussed.     

Progressive atrophy of the thymus in mice carrying Lewis lung carcinoma grafts

Summary A rapid and progressive thymus atrophy in B₆D₂ mice following transplantation of Lewis lung carcinoma cells is reported. Spleen weight, however, increased in tumor-carrying animals. Tumor extracts failed to induce these alterations. The mechanism of these perturbations of the immune system in tumor-carrying animals is discussed.This work was supported by the Norwegian Cancer Society     

Experiments on clutch size and nest size in passerine birds

Summary Results of experiments on three passerine species suggest that brood size may be constrained by nest size, since the breeding success of pairs provided with large nestcups was greater than that of those provided with small artificial nestcups. These results may have important implications, e.g. to the design of experiments involving manipulation of clutch and brood size. A small nestcup is requisite for successful hatching during the incubation period, but a large one for successful rearing during the nestling period. In nature this difference may select for types of nesting materials that are elastic, such as mosses and lichens. However, experiments showed that such materials rapidly absorb rainwater but only slowly dry out. In addition, because large nests dry out more slowly than small nests, selection will favour small nests among those open-nesting species that have exposed nests. A further possible nest size constraint on open-nesters is nest predation. However, no difference in the predation rate was found in experiments with small and large artificial nests.     

Taxonomic and biological notes on a species of Iphitime (Polychaeta, Eunicida) associated with Pagurus prideaux from western Norway

On the basis of 658 specimens collected over an 11 year period, the symbiotic eunicid polychaete, Iphitime paguri Fage & Legendre, 1934, is redescribed, and its biology in its presumed preferred host, Pagurus prideaux Leach, 1815, is outlined. The main ecological part is based on sampling of Pagurus on five occasions throughout a year in Raunefjorden, southwest of Bergen. Iphitime paguri turned out to have a strong sexual dimorphism, both in outer appearance and in the morphology of the jaws. Both juveniles and mature individuals of both genders are described. The infestation rate of Pagurus prideaux was very high (as opposed to the low reported infestation rate in Pagurus bernhardus, generally regarded as the host of this species) and the symbiotic polychaetes turned out to have a distinct pattern of host utilization in different life stages. Ripe males and females were, at certain times of the year, generally found more or less intertwined in the apex of the gastropod shell inhabited by its host. Small larval stages were found in the same place. Intermediate size groups were found in the gill chamber and in a sulcus on the carapax of the pagurid host.     

Clinical mastitis in ewes; bacteriology,epidemiology and clinical features

Background  

Clinical mastitis is an important disease in sheep. The objective of this work was to identify causal bacteria and study certain epidemiological and clinical features of clinical mastitis in ewes kept for meat and wool production.     

Growth and sex ratio of nestlings in two species of crows: how important is hatching asynchrony?

Summary In experimental studies of avian hatching paterns offspring sex has been neglected. This may be a problem if nestling growth and mortality is sex biased, and if this bias is influenced by hatching spread. In a field study of two crow species, the magpie Pica pica and the hooded crow Corvus corone cornix, we manipulated hatching spread. Both species have asynchronous hatching, and adult males are larger than females by 12–14%. The sex ratios obtained from the different experimental groups on day 24 post-hatch (total sample n = 403) did not deviate significantly from unity, nor did the sex ratios obtained among young newly hatched in an incubator (total sample n = 305). Male and female offspring were of similar size at hatching but males were larger on day 24 post-hatch. Males seemed to be more costly to rear than females, judging by the 20% difference in the mean amounts of food found in the gizzards of the young on day 24 post-hatch. Dimorphism in body size did not seem to be influenced by degree of hatching spread. Asynchronous hatching did not seem to be needed to produce high quality offspring of the larger sex (i.e. males), nor did asynchronous hatching help to ensure equal parental investment in male and female progeny. One reason for the latter negative results may be that the size dimorphism of the two crow species studied were relatively small.