The reconstitution of a hybrid histone octamer containing avian 110Cys-des-thio-histone H3 and sea-urchin 73Cys-histone H4

A hybrid histone octamer was reconstituted from erythrocyte H2A and H2B, avian [110 Cys-des-thio]histone H3 and the sea-urchin sperm [73Cys]H4 variant. [110Cys-Des-thio]histone H3 was prepared by reaction of natural H3 with Raney nickel. The ability of the hybrid octamer to crystallize to the same form as the natural octamer demonstrated that the chemical modification of cysteine to alanine in H3 and the mutation from threonine to cysteine in sperm H4 do not alter histone-histone interactions in the octamer. Since the sulfhydryl groups of both H4 molecules are fully accessible to 5,5'-dithiobis(2-nitrobenzoate) these residues provide suitable sites for the introduction of a single cysteine-specific label per H4 molecule in the octamer.     

Preservation of capsular material of streptococcal cells by specific lectins determined by immunoelectron microscopy

Summary We describe the use of lectins as specific stabilizing agents for the polysaccharide capsular components of two Gram-positive bacteria,Streptococcus agalactiae andStreptococcus bovis. Treatment of bacterial suspensions with wheatgerm agglutinin and concanavalin A allowed better morphological preservation as well as immunoelectron microscopic localization of a capsular component (lipoteichoic acid) by employing specific antibodies and the protein A-gold technique. Data obtained indicate that lectins are useful agents in preserving highly water-soluble capsular components during the electron microscopy procedures for both unembedded and embedded samples.     

Influence of steady-state and fluctuating salinities on the oxygen consumption and activity of some brackish water shrimps and fishes

Oxygen consumption, locomotory activity and, in some cases, osmoregulatory responses of different populations of Palaemon adspersus (Rathke) and Pomatoschistus microps (Krøyer) from the Isefjord ($\text{S 19‰}$) and Karrebaek Fjord ($\text{S 12‰}$) in Denmark and the Barther Bodden ($\text{S 6‰}$) in the G.D.R. to short-term salinity fluctuations, and after long-term adaptation, were tested. The same tests were performed on populations of Gasterosteus aculeatus (L.), Palaemonetes varions (Leach) (both from Barther Bodden, G.D.R.) and Palaemon elegans (Rathke) (Black Sea, Bulgaria, $\text{S 18‰}$). The steady-state experiments showed that the standard metabolic rates of P. adspersus and Pomatoschistus microps reach their lowest levels at mean biotope salinities at both 10 and 20°C. In contrast, the routine metabolic rates of both species are independent of salinity in the ecological salinity range.All Palaemon adspersus and Pomatoschistus microps populations responded to sudden changes in salinity with increased locomotory activity and respiration regardless of the direction of stressing. Metabolic adaptation in these euryhaline species, which is not synchronous with osmotic readjustment, takes from 5 to 12 h, depending on the salinity gradient.The polystenohaline Palaemon elegans from the Black Sea and the holeuryhaline Palaemonetes varians from the Barther Bodden exhibit similar short adaptation times (≈ 2 h) to identical salinity gradients but in different salinity zones.     

Ultrastructural localization of the mannose 6-phosphate receptor in rat liver

An affinity-purified rabbit antibody against rat liver mannose 6- phosphate receptor (MP-R) was prepared. The antibody was directed against a 215 kd-polypeptide and it recognized both ligand-occupied and free receptor. Anti-MP-R was used for immunofluorescence and immunoelectron microscopy of cryosections from rat liver. MP-R was demonstrated in all parenchymal liver cells, but not in endothelial lining cells. MP-R labeling was found at the entire plasma membrane, in coated pits and coated vesicles, in the compartment of uncoupling receptor and ligand, and in the Golgi complex. Lysosomes showed only scarce MP-R label. In double-labeling immunoelectron microscopy, MP-R co-localized with albumin in the Golgi cisternae and in secretory vesicles with lipoprotein particles. Cathepsin D was associated with MP- R in the Golgi cisternae. This finding indicates that MP-R/cathepsin D complexes traverse the Golgi complex on their way to the lysosomes. The possible involvement of CURL in lysosomal enzyme targeting is discussed.     

Morphofunctional study of the digging system of the Namib Desert Golden mole (Eremitalpa granti namibensis): cinefluorographical and anatomical analysis

Digging locomotion of Namib Golden moles has been studied by making X–ray cinematograph films, and the morphology of their locomotor system investigated by means of radiographs and dissections. Biomechanical interpretations of the data so obtained show that moving forwards results from a cyclical compacting and decompacting of the surrounding sand. The whole step–cycle IS made up of a buttressing phase followed by several digging propulsion phases.     

Butyrophilin,an apical plasma membrane-associated glycoprotein characteristic of lactating mammary glands of diverse species

Lipid globule membranes were isolated from human and bovine milk and from the milk of sheep, goat, pig, rat and guinea pig, and their polypeptide compositions were analyzed. The major polypeptides with molecular weights similar to that of bovine butyrophilin were separated by gel electrophoresis, isolated and characterized with respect to isoelectric point, molecular weight, immunological cross-reactivity and peptide composition after proteolytic cleavage. We show that in all species examined these proteins are similar to bovine butyrophilin in (i) their relative insolubility in buffers of low and high ionic strength and in non-denaturing detergents, (ii) the occurrence of several isoelectric variants, and (iii) patterns of peptides obtained by protease digestion. It is concluded that closely related proteins are major constituents of the cytoplasmic coat structures associated with milk lipid globule membranes of many species, and we propose the name butyrophilins for this group of proteins. Bovine and human butyrophilins are glycosylated with relatively large amounts of glucosamine, mannose, glucose and galactose but little fucose, sialic acids or galactosamine. Most if not all of the sugar residues are associated with an acetone-soluble peptide fragment of $\text{M}{}_{\mathrm{<mtext>r</mtext>}}$ 12 000–16 000 focusing at about pH 4.0. We suggest that this fragment contains a membrane-spanning peptide sequence and is involved in the attachment of the cytoplasmic coat to the membrane of the milk lipid globule.     

Glucose Metabolism in Neisseria gonorrhoeae

The metabolism of glucose was examined in several clinical isolates of Neisseria gonorrhoeae. Radiorespirometric studies revealed that growing cells metabolized glucose by a combination on the Entner-Doudoroff and pentose phosphate pathways. A portion of the glyceraldehyde-3-phosphate formed via the Entner-Doudoroff pathway was recycled by conversion to glucose-6-phosphate. Subsequent catabolism of this glucose-6-phosphate by either the Entner-Doudoroff or pentose phosphate pathways yielded CO(2) from the original C6 of glucose. Enzyme analyses confirmed the presence of all enzymes of the Entner-Doudoroff, pentose phosphate, and Embden-Meyerhof-Parnas pathways. There was always a high specific activity of glucose-6-phosphate dehydrogenase (EC 1.1.1.49) relative to that of 6-phosphogluconate dehydrogenase (EC 1.1.1.44). The glucose-6-phosphate dehydrogenase utilized either nicotinamide adenine dinucleotide phosphate or nicotinamide adenine dinucleotide as electron acceptor. Acetate was the only detectable nongaseous end product of glucose metabolism. Following the disappearance of glucose, acetate was metabolized by the tricarboxylic acid cycle as evidenced by the preferential oxidation of [1-(14)C]acetate over that of [2-(14)C]acetate. When an aerobically grown log-phase culture was subjected to anaerobic conditions, lactate and acetate were formed from glucose. Radiorespirometric studies showed that under these conditions, glucose was dissimilated entirely by the Entner-Doudoroff pathway. Further studies determined that this anaerobic dissimilation of glucose was not growth dependent.