Postembryonic development of the parasitic amphipodHyperia galba

Hyperia galba Montagu is associated with gelatinous zooplankton as are many species of the Hyperiidea. The hosts preferred in the European seas are the large scyphomedusaeAurelia aurita, Chrysaora hysoscella, Rhizostoma pulmo, Cyanea capillata andCyanea lamarckii, which harbour the first developmental stages. The anamorphic development produces young that are incapable of swimming at the time of hatching. They are characterized by an embryonic abdomen without extremities and external segmentation; the eyes are not completely developed and the mouth is primitive lacking bristles, molar and incisor. The postembryonic development, described in detail, is subdivided into two phases: the pantochelis phase and the protopleon phase; the former comprises only one stage; the latter can be subdivided into four stages. In the course of postnatal development the larval organs are reduced and characters typical of the adult are gradually differentiated.H. galba plays an important role as obligatory endoparasite of scyphomedusae at least during the first stages of development; without a host this amphipod cannot survive, neither benthically nor in the plankton. The transition from life in the female's marsupium to endoparasitism in the jellyfish generally occurs during stage of the postembryonic development which is the first stage of the protopleon phase. The specific adaptations of its reproductive biology to a parasitic mode of life such as moult inhibition under starvation, development of larval organs and the behavioural patterns of the females as well as the young are described. Further, the influence of external factors such as temperature and food supply on the course of development is examined. Dedicated to Prof. Dr. H. Mergner on the occasion of his 70th birthday.     

Specificity of restriction endonucleases and methylases--a review

The properties and sources of all known restriction endonucleases and methylases are listed. The enzymes are cross-indexed (Table I), classified according to their recognition sequence homologies (Table II), and characterized within Table II by the cleavage and methylation positions, the number of recognition sites on the double-stranded DNA of the bacteriophages lambda, phi X174 and M13mp7, the viruses Ad2 and SV40, the plasmids pBR322 and pBR328, and the microorganisms from which they originate. Other tabulated properties of the restriction endonucleases include relaxed specificities (integrated into Table II), the structure of the generated fragment ends (Table III), and the sensitivity to different kinds of DNA methylation (Table V). In Table IV the conversion of two- and four-base 5'-protruding ends into new recognition sequences is compiled which is obtained by the fill-in reaction with Klenow fragment of the Escherichia coli DNA polymerase I or additional nuclease S1 treatment followed by ligation of the modified fragment termini [P3]. Interconversion of restriction sites generates novel cloning sites without the need of linkers. This should improve the flexibility of genetic engineering experiments. Table VI classifies the restriction methylases according to the nature of the methylated base(s) within their recognition sequences. This table also comprises restriction endonucleases which are known to be inhibited or activated by the modified nucleotides. The detailed sequences of those overlapping restriction sites are also included which become resistant to cleavage after the sequential action of corresponding restriction methylases and endonucleases [N11, M21]. By this approach large DNA fragments can be generated which is helpful in the construction of genomic libraries. The data given in both Tables IV and VI allow the design of novel sequence specificities. These procedures complement the creation of universal cleavage specificities applying class IIS enzymes and bivalent DNA adapter molecules [P17, S82].     

Increased carbohydrate substitution of lipoteichoic acid during inhibition of protein synthesis.

Decreases in electrophoretic mobilities of intracellular lipoteichoic acid, intracellular deacylated lipoteichoic acid, and extracellular deacylated lipoteichoic acid were observed during inhibition of protein synthesis in Streptococcus faecium after exposure to chloramphenicol or valine deprivation. Increased carbohydrate content, and thus an increased mass-to-charge ratio, rather than changes in ester alanine content or novel fatty acid substitutions, appeared to account for the decreased electrophoretic mobilities. The increase in carbohydrate content, as judged from mobility measurements, was progressive over time and appeared to occur on biosynthetically new lipoteichoic acid as well as on lipoteichoic acid made before inhibition of protein synthesis.     

Ultrastructure of synaptosomes from one-day old and adult rat brain stem

Summary The ultrastructure and protein content of the five subfractions of the crude mitochondrial fraction from the brain stem of the 1-day old and adult rat was examined. The morphological composition of the subfractions after fixation in glutaraldehyde and osmiumtetroxide in the adult rat brain stem resembled that previously reported for the whole brain; synaptosomes sedimented in a sucrose gradient in subfractions C and D. In the 1-day old rat, mature synaptosomes were found in subfractions A, B, C and D; E contained mainly free mitochondria. 80–95% of the processes in the adult and 10–30% in the 1-day old rat contained synaptic vesicles which were of four types: (1) small agranular vesicles (2) large dense core vesicles (3) large agranular vesicles (4) coated vesicles. Pre- and postsynaptic membrane thickenings were demonstrated in many nerve-ending particles. In the subfractions of the 1-day old rat the protein content was one half and the distribution resembled that in the adult. Evidently nerve endings develop faster in the brain stem than in cortical areas; a serotoninor adrenergic origin of the early synaptosomes is suggested.This study was supported by a grant from the Paulo Foundation.     

Gallium-67 Scans in the Diagnosis of Pyelonephritis

Gallium-67 (⁶⁷Ga) citrate was administered intravenously (50 microcuries per kg of body weight) to patients in whom acute and chronic urinary tract infections were suspected. Scanning was done, using both the Anger-type scintillation camera and the rectilinear scanner, 24 to 78 hours after injection of the isotope.The preliminary results imply that ⁶⁷Ga renal uptake is present in patients with pyelonephritis whether overt or silent, as well as in patients with uretero-sigmoidostomies. However, ⁶⁷Ga renal uptake is not present in patients with radiographic evidence of chronic pyelonephritis without active infection and in patients without renal disease.     

Cold-sensitive Mutations in Salmonella typhimurium Which Affect Ribosome Synthesis

A number of mutations (45) expressed as cold-sensitive conditional lethal pheno-types were screened by transduction for their linkage to the streptomycin-resistance locus; 7 showed such linkage. Of these, two were studied in greater detail. The sedimentation profiles of ribosomes from cultures grown at low temperature differed from wild type and from one another. Both mutants lost ribonucleic acid control at low temperature. It is suggested that a high proportion of mutants expressing a cold-sensitive phenotype harbor mutations in genes affecting ribosome synthesis or regulation.     

Physiologische und biochemische Beiträge zur Taxonomie der Gattung Chlorella

Zusammenfassung Es wurde die Verwendbarkeit von Glutaminsäure, Glutamin, Nicotinsäure, Nicotinsäureamid und Purin als Stickstoffquelle für die Kultur von 71 autotrophen Chlorella-Stämmen, die 8 Arten angehören, untersucht. Im Licht zeigen mit Glutaminsäure 63 und mit Glutamin 67 Stämme gutes Wachstum. Nicotinsäure wird dagegen nur von 1 Stamm, Nicotinsäureamid von 9 und Purin von 16 Stämmen verwertet. Die Verwendbarkeit der 5 geprüften organischen Stickstoffverbindungen als N-Quelle ist innerhalb der Gattung Chlorella als taxonomisches Merkmal zur Charakterisierung von Arten nicht geeignet. Lediglich die 7 Stämme von Chlorella kessleri unterscheiden sich durch gutes Wachstum mit Nicotinsäureamid von der sonst recht ähnlichen Chlorella luteoviridis sowie von den übrigen Arten.

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Physiological and biochemical contributions to the taxonomy of the genus Chlorella IV. Utilization of organic nitrogen compounds

Summary The utilization of glutamic acid, glutamine, nicotinic acid, nicotinamide, and purine as sources of nitrogen for growth in the light of 71 autotrophic Chlorella strains belonging to 8 species was studied. Whereas 63 strains grow well with glutamic acid and 67 with glutamine, nicotinic acid is used by 1, nicotinamide by 9, and purine by 16 strains only. Utilization of the 5 organic nitrogen compounds tested cannot serve as a taxonomic character in the genus Chlorella. However, the 7 strains of Chlorella kessleri differ in their good growth with nicotinamide from the otherwise rather similar Chlorella luteoviridis and from the other species.

     

Inhibition of nitrite assimilation by uncouplers of phosphorylation

Summary Carbonyl cyanide m-chlorophenylhydrazone (CCCP) and pentachlorophenol (PCP), two powerful uncouplers of phosphorylation, specifically inhibit the assimilation of nitrite in the course of nitrate reduction. These results support our former conclusion that high-energy phosphate is involved in the metabolism of nitrite.