Trophi Structure in Bdelloid Rotifers

Bdelloids show a rather uniform morphology of jaws (trophi), named ramate. The most recognizable feature is the presence of a series of teeth forming unci plates. The unci are not uniform in size; each plate has 1–10 major median teeth. Using SEM pictures of trophi and data from the literature, we analyzed the number of major unci teeth in relation to trophi size, total number of teeth, and environmental features. Variability in the number of major unci teeth in bdelloids is not related to trophi size or to total number of unci teeth, while total number of unci teeth and trophi size seem to be related to each other: larger trophi in general have more teeth than smaller trophi. Few major teeth are more common in species living in water bodies where they possibly eat unicellular algae, while more major teeth are more common in species living outside water bodies, among mosses and lichens, where they possibly eat bacteria.     

Rotifers from the Canadian high arctic (Devon Island,Northwest territories)

Samples from eight water bodies in the region of Truelove and Sparbo Hardy Lowland, Devon Island (75 ° 30 N, 86 ° 00 W) yielded 70 taxa (4 Bdelloidea, 66 Monogononta) of rotifers, nineteen of which are new records for the Canadian High Arctic.     

Contributions to the knowledge of African Rotifers I. Rotifers from Senegal

24 plankton samples, collected in different parts of the Republic of Senegal (W. Africa) were examined for their rotifer content. Seventy taxa were identified to species level, some of which were present in different forms. Thirty three taxa and forms are new to Senegal, three species are new to Africa. Attention is paid to a cruciform population of Asplanchnella sieboldi and to a Brachionus quadridentatus population of very small dimensions. Two new taxa are described: Brachionus cf. angularis and Brachionus bidentatus senegalensis Koste & De Ridder.     

CNS--endocrine pancreas system. III. Further studies on the vagal responsiveness to insulin deficiency

Distribution and activity of acetylcholinesterase (AChE) in the neurons of the central vagal nuclei at the level of the medulla oblongata were studied in intact and alloxan-diabetic adult male rats by Gomori's histochemical method. Peculiarities of intracellular distribution of the enzyme in the Nucl. dorsalis n. vagi (ND) and Nucl. ambiguus n. vagi (NA) of intact animals were demonstrated. Changes in the ratio of cholinergic neurons with moderate and strongly-positive AChE staining reactions were revealed in the ND of alloxan-diabetic rats. The dynamics of the changes attested to increased AChE activity of these neurons in response to insulin deficiency. The data obtained are additional evidence for the responsiveness of ND neurons to insulin deficiency, which was demonstrated earlier in alloxan-diabetic rats by karyometry (Akmayev and Rabkina, 1976 b). It is suggested that changes in the plasma glucose or insulin levels may be the stimulus that influences the activity of the ND cholinergic neurons. By means of this mechanism the central vagal nucleus at the medulla oblongata level may be implicated in the feedback control of insulin secretion.     

Radiation damage to bull sperm motility. III. Further x-ray studies.

The results of previous radiation experiments, which indicated that the centriole serves as a control center for bull sperm motility, appear to be in conflict with experiments showing that the bull sperm flagellum is an autonomous oscillator. To resolve this conflict experiments were conducted to calibrate absolutely the dose-response curves for the radiation damage, and to measure the force production and the mechanochemical energy conversion after irradiation in bull sperm. The results indicate that the centriole acts as a mechanical anchor for the contractile fibers.     

Rotifers from the Balearic archipelago

Ecological and historical factors of the Balearic archipelago (Western Mediterranean Sea) result is some peculiarities to its rotifer fauna. A group of warm-stenothermous species are frequent seasonally in the islands. Among them the occurrence of Keratella procurva (Thorpe, 1912), a pantropical species, is remarkable, and this is found more or less abundantly on each island. We briefly describe the different habitat categories of the archipelago. Clustering the collected species we relate each community type to its habitat; in this sense we distinguish 4 community type in the islands corresponding to different environments. This work also summarizes all the obtainable data on the rotifer fauna of the Balearic archipelago, adding the results of the investigations done in the last survey (spring, 1989); a checklist, including 100 species from the archipelago, is shown (69 Majorca, 72 Minorca, 24 Ibiza, 25 Formentera). Some examples of pantropical distribution are given, and the biotic and abiotic factors which determine the colonization of the islands by these species are discussed.     

Contributions to the rotifer fauna of ORISSA,India

This paper deals with 36 species of monogonont rotifers (belonging to 10 eurotatorien families) collected from Sambalpur (Orissa State) in Eastern India. Of the reported taxa, 15 species have been added as new records to the previous list from this region while one species represents a new record from this country.     

Further studies on the thymocyte stimulating factor.

The thymocyte-stimulating activity produced by spleen cells cultured in the presence of PHA (cell. Immunol.17, 495, 1975) was further investigated. It was found that this activity is caused by a factor having the chemical properties of a protein with a molecular weight of 30,000–32,000 that, at high concentration, probably dimerizes to a molecule of molecular weight about 55,000 as measured by Sephadex gel filtration. This factor is produced also in mixed lymphocyte cultures of CBA and C57 spleen cells. The observation that the factor produced in the presence of PHA and the factor produced in the mixed lymphocyte cultures have the same molecular weight and the same rate of denaturation at two different temperatures suggests that they are the same, or very similar, substance. The fact that spleen cells of nu/nu mice do not produce thymocyte-stimulating factor suggests that thymus-dependent cells are involved in the production of this factor. This assumption is consistent with the observation that spleen cells of mice less than two weeks old (which show a very small response to PHA) do not produce significant amounts of thymocyte-stimulating factor. On the other hand, results of experiments with hydrocortisone-injected mice suggest that the target cell for thymocyte-stimulating factor is the immature, cortisone-sensitive thymocyte. The properties of thymocyte-stimulating factor are discussed and compared to those of factors with similar actions reported in the literature.     

Further studies on the genus Berkeleya Grev.

Detailed light and electron microscopical studies on the diatom genus Berkeleya Grev. clarify relationships between the four species and support the separtion of B. fragilis and B. micans as two distinct taxa.     

Further studies on prostaglandins. III. Effect of prostaglandins on thyroid activity as assessed by 125I.

The effect of crude prostaglandins extraced from prostate glands of camels as well as that PGE1, on the thyroid activity of male immature Boskat rabbits, was investigated. The iodinated amino acid fractions (T1, T2, T3 and T4) in the serum of the injected groups were determined in control and treated animals. Cytological work on sections of the thyroid glands of the treated and control rabbits were performed to study the effect on subcellular level. The results indicate that both crude and pure prostaglandins have a stimulating effect on thyroid activity. This was indicated by the increased 125I uptake of the thyroids of rabbits and evidenced histologically. PGE1, was found to be more effective as compared with the crude prostaglandins. The indinated amino acid and hormone fractions in the serum of the treated groups showed that T2 was increased as a result of injection of the crude prostaglandins, and T4 was increased after PGE1 injection. Tables and figures explained diversed effect.     

Studies on peroxisomes III. Further studies on the intraparticulate localization of peroxisomal components in the liver of the rat

The peroxisome-rich fraction prepared from rat liver homogenate was treated by various procedures and the behavior of the peroxisomal core on sucrose density gradient centrifugation was investigated.Peroxisomes were destroyed by various treatments, such as pH 9.0, VirTis blender, sonication and deoxycholate, resulting in the solubilization of catalase from the particles. Urate oxidase was not solubilized at all such treatments. Although D-amino acid oxidase was solubilized by treatments with deoxycholate and VirTis blender, this enzyme was found to be resistant to solubilization by treatment with pH 9.0 or sonication, in contrast to catalase.When the peroxisomal core was investigated, using urate oxidase activity as a marker, its density proved to be changed when submitted to various treatments. These results indicated that the peroxisomes consist of four compartments: a catalase-containing compartment (matrix), a urate oxidase containing compartment (core), a D-amino acid oxidase containing compartment and a low density compartment which is proposed for the first time in the present paper. Furthermore, it was also found that the last two compartments seem to be bound to the core, though the binding might be weak.     

Further studies on endo-beta-N-acetylglucosaminidase D1.

The purification procedure for endo-beta-N-acetylglucosaminidase D was improved to yield an enzyme preparation which was homogeneous upon gel electrophoresis. The molecular weight of the enzyme as estimated by Sephadex G-200 column chromatography was 280,000, while SDS-gel electrophoresis after reduction with 2-mercaptoethanol gave a value of 150,000. The purified enzyme did not show any chitinase, hyaluronidase or lysozyme activity. In the presence of exoglycosidases removing peripheral sugars, the endoglycosidase acted on serum glycoproteins such as transferrin and fetuin. The enzyme also hydrolyzed an oligosaccharide, (Man)5(GlcNAc)2, indicating that the peptide portion of substrates does not have much effect on susceptibility to the enzyme.     

Further studies on the smooth-surfaced membranes isolated from rat brain

The light and heavy smooth-surfaced membranes (LSM and HSM), which had densities corresponding to 1.08 M and 1.28 M sucrose, respectively, were isolated from rat brain and some of their biochemical properties were investigated. Both LSM and HSM showed high Na+,K+-ATPase activity and, in particular, in HSM the activity was four times (21.55 mumol/mg protein/h) higher than that of the brain homogenate. High 2',3'-cyclic nucleotide 3'-phosphodiesterase activity (293.4 mumol/mg protein/h) was characteristic of LSM. 5'-Nucleotidase and acetylcholinesterase activities were also higher in LSM than in HSM. SDS-polyacrylamide gel electrophoresis showed that LSM and HSM had many protein component and that low molecular weight proteins such as proteolipid protein and basic protein were almost absent, in contrast with myelin and myelin-like membrane. GM1 ganglioside constituted the major class of total ganglioside in both LSM and HSM. These biochemical findings suggested that LSM is a membrane that has not previously been described, or a membrane fraction related to the oligodendroglial plasma membrane.