A model for the tertiary structure of transfer ribonucleic acids

In view of the possible changes of the structure of DNA at different relative humidities, a similar model for tRNA is proposed. In the native form, the sugar phosphate backbone folds repeatedly on itself resulting in a circular rod structure of about 50 Å in length and about 25 Å in diameter. Both the amino-acyl end and the anticodon site are surrounded by segments of base sequences common to different tRNA’s.     

Biological activity of 125iodine labelled globin mRNA in an Ehrlich ascites cell-free system

Globin mRNA was isolated from avian erythroblasts and labelled with ¹²⁵iodine to a specific activity of 4.5×10⁶ dpm μg^-1 mRNA. The labelling procedure was modified as compared to common techniques in order to protect the mRNA against degradation. When this RNA is translated in an Ehrlich ascites cell-free system globin chains are synthesized as is demonstrated by the analysis of the in vitro synthesized products. The biological activity of ¹²⁵iodine labelled mRNA has proven to be 30% of that of unlabelled mRNA.     

Immune response in human subjects at high altitude

Levels of immunoglobulins were determined in persons exposed to high altitude. The individuals studied included high altitude natives, sea level residents at high altitude for 2 years, and recent arrivals at high altitude. Increased IgG and IgA levels were found in high altitude natives and sea level residents at high altitude for 2 years when compared with sea level residents. In recent arrivals marked increase of IgG and IgG levels and slight rise in IgM was seen. Recent arrivals who suffered from high altitude pulmonary oedema showed marked elevation of IgG, IgM, and IgA. Immunoglobulin responses to both primary and secondary TAB inoculation were of a higher magnitude and more sustained at high altitude than at sea level.     

Transfer RNA genes ofZea mays chloroplast DNA

A minimum of 37 genes corresponding to tRNAs for 17 different amino acids have been localized on the restriction endonuclease cleavage site map of theZea mays chloroplast DNA molecule. Of these, 14 genes corresponding to tRNAs for 11 amino acids are located in the larger of the two single-copy regions which separate the two inverted copies of the repeat region. One tRNA gene is in the smaller single-copy region. Each copy of the large repeated sequence contains, in addition to the ribosomal RNA genes, 11 tRNA genes corresponding to tRNAs for 8 amino acids. The genes for tRNA₂ ^Ile and tRNA^Ala map in the ribosomal spacer sequence separating the 16S and 23S ribosomal RNA genes. The three isoaccepting species for the tRNAs^Leu and the three for tRNAs^Ser, as well as the two isoaccepting species for tRNA^Asn, tRNA^Gly, tRNAs^Ile, tRNAs^Met, tRNAs^Thr, are shown to be encoded at different loci. Two independent methods have been used for the localization of tRNA genes on the physical map of the maize chloroplast DNA molecule: (a) cloned chloroplast DNA fragments were hybridized with radioactively-labelled total 4S RNAs, the hybridized RNAs were then eluted, and identified by two-dimensional polyacrylamide gel electrophoresis, and (b) individual tRNAs were³²P-labelledin vitro and hybridized to DNA fragments generated by digestion of maize chloroplast DNA with various restriction endonucleases.     

Gill Monogenea of deepwater and surface fish in southeastern Australia

The faunas of gill Monogenea of marine teleost fishes in deep and surface waters of southeastern Australia are compared, based on extensive surveys: 1563 fish (66 or 67 species, 35 families, 15 orders) in deepwater; 1862 fish (46 species, 26 families, 7 orders) in surface water. Relative species diversity (number of species of Monogenea/all fish species examined) is approximately five times greater in surface waters. There is a similarly low relative species diversity of Monogenea in the northwestern Pacific and northwestern Atlantic deepwater. Deepwater Monogenea in all seas belong mainly to the Diclidophoroidea (13 of 19 species in southeastern Australia, 14 of 17 species in the northwestern Pacific, at least 9 of 12 (?) species in the northwestern Atlantic) predominantly Diclidophoridae. Important groups of surface Monogenea in southeastern Australia are the Microcotylidae (34 of 83 species), Dactylogyridae Ancyrocephalinae (15 species) and Capsaloidea (12 species); only 10 species belong to the Diclidophoroidea and 2 of those to the Diclidophoridae. It is concluded that deepsea Monogenea in southeastern Australia show no or very little relationship with surface Monogenea of the same geographical area, but close relationship with Monogenea in the deepsea of other geographical areas. Some deepsea Monogenea have a wide geographical distribution in the Atlantic and Pacific Oceans. Arctic and Antarctic Monogenea also are not related to deepwater forms. The main group of deepsea Monogenea is considered to be archaic.