Cell Biology and Algal Taxonomy and Evolution Absolute Orientations of Basal Bodies in Green Algae Evaluated by Light Microscopy

Using high magnification Nomarski interference microscopy a series of optical sections has been obtained through flagellated cells of several green algae in an attempt to establish the absolute orientation of their basal bodies. Using this technique we have confirmed that in Spermatozopsis similis basal bodies are displaced into the 1/7 o'clock position, whereas in gametes of Enteromorpha linza, and zoospores of Trebouxia erici basal bodies are displaced into the 11/5 o'clock position. In addition we report for the first time that in zoospores of Microthamnion kuetzingianum basal bodies are also displaced into the 11/5 o'clock position. Basal body absolute orientations can thus be determined by light microscopy and do not require serial section electron microscopy. The method should be useful for class-level recognition of unknown green algae at the light microscope level.     

Effects of diabetes and insulin on ketone bodies metabolism in heart

This work investigates the effect of alloxan-induced short-term diabetes (24 h) on D-3-hydroxybutyrate metabolism at physiological and non-physiological concentrations of the ketone body in the isolated non-working perfused rat heart. Also the effect of insulin (2 mU.ml⁻¹) on D-3-hydroxybutyrate metabolism was investigated in hearts from normal and diabetic rats. The rates of D-3-hydroxybutyrate utilization and oxidation and of acetoacetate production were proportional to D-3-hydroxybutyrate concentration. The utilization of D-3-hydroxybutyrate showed saturation kinetics in hearts from normal and diabetic rats, in the presence and absence of insulin. Acute short-term diabetes augmented D-3-hydroxybutyrate utilization and oxidation at 1.25 and 2.5 mM DL-3-HB, with no significant effect at higher concentrations, but increased acetoacetate production at all investigated concentrations. In hearts from normal rats, insulin enhanced D-3-hydroxybutyrate utilization and oxidation at 2.5, 5, and 10 mM DL-3-HB, but no effect was observed at the lowest (1.25 mM) and highest (16 mM) DL-3-HB concentrations. Insulin had no effect on D-3-hydroxybutyrate metabolism in hearts from diabetic rats. No significant effect of insulin on the rate of acetoacetate production in normal and diabetic states was observed.     

Woronin bodies in arthrinium genus

Woronin bodies are present near all septal pores and in conidia of Arthrinium strains and may regulate cytoplasmic flow in both injured and actively growing healthy colonies. They vary in size and frequency, the central one plugs the septal pores in actively developing colonies and in mature conidia. The septa are thinner in the Woronin-body region.     

Reserve substances inPaxillus involutus sclerotia

Summary The ectomycorrhizal fungus,Paxillus involutus, produces sclerotia in culture. These can be induced to form on agar medium by exposing mycelium grown at 25°C to various temperatures between6°C and 15°C. Sclerotia formed at 10°C and above were large and covered with drops of exudate, while those formed at 6°C or 8°C were very small and did not produce an exudate. Mature sclerotia were bounded by a compact rind and contained abundant storage reserves. Histochemistry of the larger sclerotia showed large quantities of protein stored as protein bodies in the cytoplasm, lipid present as small droplets, glycogen granules stored in the cytoplasm and polyphosphate present as small granules in the cytoplasm and in the protein bodies. Energy dispersive X-ray microanalysis confirmed the presence of phosphate in the granules and was used to map its distribution throughout the sclerotium. The smaller sclerotia induced at 8°C and below on the same medium had the same basic structure and composition, but lacked the complex phenolic cell network found in large sclerotia, and had abundant extracellular polysaccharides. The rind was not well developed and these small sclerotia are interpreted to have been arrested at an early stage of development.     

Nucleosomal organization of chromatin in sperm nuclei of the bivalve mollusc Aulacomya ater

The sperm nuclei of Aulacomya ater, family Mitylidae, contain three proteins (X, Aa5 and Aa6) which are specific to this cell type coexisting with a set of five somatic-type histones. Information about the chromatin structure resulting from this kind of association is scarce. Therefore, we have probed the structure of this sperm chromatin through digestion with micrococcal nuclease in combination with salt fractionation. The data obtained have allowed us to propose a nucleosomal arrangement for this chromatin. However, two types of nucleosomes would be present in agreement with their protein components.     

Isolation and partial characterization of a protein kinase NII from wheat germ chromatin

A protein kinase, type NII, has been purified from wheat germ chromatin. The enzyme, which uses both ATP and GTP as phosphoryl donors, catalyzes the phosphorylation of casein, phosvitin and E. coli RNA polymerase, but not of histone proteins. Polypeptide bands at 46 kDa, 37 kDa and 25 kDa were estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Autophosphorylation of the 25 kDa subunit was observed following incubation of the purified kinase with (-³²P)ATP and (-³²P)GTP.     

Ultrastructural visualization of exocytosis in the pig pineal gland

Summary The pinealocytes of the pig contain conspicuous dense bodies, the nature and role of which are not yet fully elucidated. The aim of this study was to demonstrate whether or not these structures are involved in the secretion process. The tannic acid-Ringer incubation (TARI)-method, which allows a clear-cut ultrastructural study of secretory discharge by exocytosis, has been used. The results indicate that pig pinealocytes release the content of the dense bodies with an amorphous inner structure into the extracellular space via exocytosis and that this secretion is quantitatively important. The secreted material is proteinaceous in nature; this indicates that polypeptides are released by the pineal.     

Purification of ribulose 1,5-bisphosphate carboxylase/oxygenase and of carboxysomes from Thiobacillus thyasiris the putative symbiont of Thyasira flexuosa (Montagu)

The bacterial symbionts of many marine invertebrates contain ribulose 1,5-bisphosphate (RuBP) carboxylase but apparently no carboxysomes, polyhedral bodies containing RuBP carboxylase. In the few cases where polyhedral bodies have been observed they have not been characterised enzymatically. Polyhedral bodies, 50–90 nm in diameter, were observed in thin cell sections of Thiobacillus thyasiris the putative symbiont of Thyasira flexuosa and RuBP carboxylase activity was detected in both soluble and particulate fractions after centrifugation of cell-free extracts. RuBP carboxylase purified 90-fold from the soluble fraction was of high molecular weight and consisted of large and small subunits, with molecular weights of 53,110 and 11,100 respectively. Particulate RuBP carboxylase activity was associated with polyhedral bodies 50–100 nm in diameter, as revealed by density gradient centrifugation and electron microscopy. Therefore, the polyhedral bodies were inferred to be carboxysomes. Native electrophoresis of isolated carboxysomes demonstrated a major band which comigrated with the purified RuBP carboxylase and three minor bands of lower molecular weight. Sodium dodecyl-sulphate (SDS) gel electrophoresis of SDS-dissociated carboxysomes demonstrated nine major polypeptides two of which were the large and small subunits of RuBP carboxylase. The RuBP carboxylase subunits represented 21% of the total carboxysomal protein. The most abundant polypeptide had a molecular weight of 40,500. Knowledge of carboxysome composition is necessary to provide an understanding of carboxysome function.Abbreviations FPLC fast performance liquid chromatography - IB isolation buffer - PAGE polyacrylamide gel electrophoresis - RuBP carboxylase - ribulose 1,5-bisphosphate carboxylase/oxygenase - SDS sodium dodecyl-sulphate     

一例硬皮病人自发抗核仁抗体的免疫荧光及其与银染的比较研究

从硬皮病人血清中筛选出一例含有自发抗核仁抗体的血清,利用这个血清对核仁抗原的性质及其在细胞中随分裂周期不同产生的分布变化做了初步研究,并把结果与核仁嗜银蛋白做了比较。间接免疫荧光染色及细胞化学分析表明,这种核仁抗原的性质是蛋白质,其分布与嗜银蛋白相似,在间期,抗原呈颗粒状簇集在核仁中,而在分裂中期,抗原颗粒与染色体NORs部位接合,但有证据指出,这种抗原蛋白与核仁嗜银蛋白有所不同,同时还发现,经长时间秋水仙素处理诱导产生微核化的多核细胞中尽管微核的数目远多于细胞中NORs的数目,免疫荧光染色和银染都显示出每个微核中类核仁小体的存在。这说明(1)类核仁小体也是由核仁物质构成;(2)某些类核仁小体的产生可能与NORs无关。对这个现象的意义进行了讨论。