Parasitism on Ordovician Chitinozoa

Borings are common in chitinozoans. They are cylindrical or conical, widening towards the outer surface of the vesicle wall. It is suggested that the cylindrical borings were probably caused by bacteria. Actinomycota and lower Fungi including at least Chytridiomycota, and the conical borings mainly by chytridia. Two types of spore-like bodies, operculate and non-operculate, have been found in situ on two chitinozoan species. The spore-like bodies are of about the same size as the supposed boring organisms in chitinozoans but are never found in association with the borings. They are interpreted as cysts of ectoparasitic nannoorganisms that resemble ciliates and amoebae, and their possible use for determining the biochemical composition of the chitinozoans is briefly discussed.     

Insulin in Invertebrates and Cyclostomes

It seems increasingly clear that insulin is a hormone that doesnot occur exclusively in vertebrates. Several independent reportsnow exist giving evidence of insulin production in the digestivetissues of both deuterostomian and protostomian invertebrates.Cells with some light-microscopical and ultrastructural characteristicsof vertebrate B-cells have also been observed. Recently, evidencehas been obtained that insulin can act as a hypoglycemic hormone,promoting glycogen synthesis, also in a protostomian invertebrate,the gastropod mollusc, Strophocheilus oblongus. The endocrine pancreas of the cyclostomes occupies a key positionin the comparative endocrinology of the islet parenchyma andin the evolution of insulin production. It may represent anevolutionary link between the presumably gut-connected dispersedinsulin-producing cells of deuterostomian invertebrates andthe pancreatic islets of gnathostomian vertebrates. This hypothesiswas supported by the fact that cells with light-microscopicaland ultrastructural similarities to the islet B-cells were observedin the bile duct mucosa of the hagfish, Myxine glutinosa. However,immunofluorescent studies with antisera against human insulinand C-peptide did not show any immunoreactive material outsidethe B-cells of the endocrine pancreas. Particular attentionwas paid to elucidate the biological significance of the largecystic cavities that are so typical for the cyclostomian isletparenchyma. The working hypothesis that they may contain storedinsulin, proinsulin (or even "proto-proinsulin") was not supportedby immunofluorescence, autoradiographic, or ultrastructuralinvestigations, nor by proinsulin assays. It is possible thathagfish islet B-cells contain zinc, despite the fact that theamino acid residue in B₁₀-position is aspartic acid insteadof histidine. The biosynthesis of hagfish insulin shows a patternsimilar to that in gnathostomes. Its rate is related to theambient temperature and at 11 C the conversion of proinsulinto insulin lasts several days.     

Ultrastructural studies of some chitinozoan vesicles

Four species of Ordovician Chitinozoa from Öland, Sweden, Cyathochitina stentor, Desmochitina minor, Lagenochitina esthonica , and Lagenochitina tumida , have been investigated by transmission electron microscopy. There is very great variation in the vesicle wall ultrastructure of the specimens studied. The texture of the vesicle wall can be homogeneous or granular and can also contain denser zones. Ultrastructures such as pore canals and 'empty spaces' have been revealed. The systematic affinity of the Chitinozoa is discussed, and it is concluded that chitinozoans display typical metazoan structures represented in eggs and egg capsules of marine invertebrates and possibly also in fish.     

CHARACTERISTICS OF TERRITORIAL AND MATING CALLS IN WILLOW PTARMIGAN LAGOPUS L. LAGOPUS

ABSTRACT

During territorial behaviour and pair formation willow ptarmigan cocks and hens use several different calls. Cocks use mainly a “flight call”, a “ground call” and three different “threat calls”. Hens give similar calls to cocks. It is suggested that the structure of the calls is well adapted to (1) transmit their possible information content over long distances, and (2) make localization easier for birds during the territorial display periods, which take place mainly in poor light at dusk and dawn. We also suggest that the cock and hen calls express different degrees of aggressiveness, and that hen calls, in addition to attracting cocks, function as territorial “keep out” signals to other hens.     

Taxonomic Notes on the Swedish Domestic Reindeer, Genus Rangifer

In order to study the taxonomic relationship between domestic mountain and forest reindeer in Sweden nine skull characters on 126 and 62 animals, respectively, were measured and analysed. In addition antler width and shape of antler beam in cross-section were also measured. The differences indicate that the two groups of domestic reindeer are not entirely identical, although the differences are clearly not as plain as has been claimed. Comparing these results with earlier results it also appears that domestic forest reindeer are more in accordance with Rangifer tarandus tarandus than with R. t. jennicus , thus supporting the theory that possible influence of the latter subspecies on domestic reindeer has been considerably reduced as a result of long and intense cross breeding between the two groups of domestic reindeer.