T-DNA presence and opine production in tumors of Picea abies (L.) Karst induced by Agrobacterium tumefaciens A281

The hypervirulent Agrobacterium tumefaciens strain A281 formed frequent tumors (31%) on Picea abies (Norway spruce), an economically important tree species in Swedish forests. Three-month-old seedlings were inoculated and tumors were established that grew hormone-independently in culture. Tumors contained agropine and mannopine/mannopinic acid as determined by acid pH paper electrophoresis. In addition, DNA hybridization studies showed that the DNA from these tumor lines contained sequences homologous to Ti plasmid T-DNA, whereas wild-type spruce seedling DNA did not. These results suggest that Agrobacterium vectors can be used for gene transfer into this important forest species.     

Identifying DNA polymorphisms in human TCRA/D variable genes by direct sequencing of PCR products

 The T-cell receptor (TCR) is a highly variable molecule composed of two polypeptide chains that recognize antigenic peptides in the context of major histocompatibility complex (MHC) molecules. In this study, we describe a sequence-based search for germline polymorphisms in the variable (V) gene segments of the human TCRA/D locus. Thirty different V gene segments were amplified from six to eight unrelated individuals and sequenced from low melting point agarose. Twenty-seven polymorphisms were identified in 15 V gene segments. These polymorphisms are mainly single nucleotide substitutions, but an insertion/deletion polymorphism and a single dinucleotide repeat with variable length were also seen. Of the 15 sequence variations found in the coding regions, six are silent and nine encode amino acid changes. All of the amino acid changes are found at non-conserved residues, frequently in the hypervariable regions, where they may influence MHC and/or peptide recognition. Therefore, it is possible that germline variations in TCR genes could influence an individual’s immune response, and may also contribute to susceptibility to diseases such as autoimmunity. Received: 9 January 1996 / Revised: 22 February 1996     

Endurance training alters alanine and glutamine release from muscle during contractions

The release of alanine and glutamine from perfused muscle of trained and control animals was investigated. Release rates did not differ between trained and control muscle at rest. During contractions in trained muscle, alanine release was higher than at rest, while glutamine release was transiently increased. Phenylalanine release did not differ between trained and control muscle, implying that protein degradation was not increased in trained muscle. The muscle cellular adaptations to training include a selective modification of amino acid output, which could potentially influence gluconeogenic flux and alter muscle ammonia levels during contractions.     

Approaches to breeding for salinity tolerance - a case study on Porteresia coarctata

Cereals are the world's major source of food for human nutrition. Among these, rice (Oryza sativa) is the most prominent and represents the staple diet for more than two-fifths (2.4 billion) of the world's population, making it the most important food crop of the developing world (Anon., 2000a). Rice production in vast stretches of coastal areas is hampered due to high soil salinity. This is because rice is a glycophyte and it does not grow well under saline conditions. In order to increase rice production in these areas there is a need to develop rice varieties suited to saline environments. Research has shown that Porteresia coarctata, a highly salt tolerant wild relative of rice growing in estuarine soils, is an important material for transferring salt tolerant characteristics to rice. It is quite possible that Porteresia may be used as a parent for evolving better and truly salt resistant varieties. The inadequate results and the difficulties associated with conventional breeding techniques necessitate the use of the tools of crop biotechnology in unravelling some of the characteristics of Porteresia that have been highlighted in this report. In view of the limited resources available for increasing salinity tolerance to the breeders to wild rice germplasm, Porteresia is undoubtedly one of the key source species for elevating salinity tolerance in cultivated rice.     

Needle aspiration cytology of a benign and a malignant schwannoma

The histologic and cytologic features of an uncommon solitary, malignant schwannoma and a benign schwannoma are presented. The benign tumor revealed characteristic interlacing fascicles of spindle-shaped cells on both histology and cytology. The malignant schwannoma produced a variable histologic pattern that was selectively sampled from a recurrence in a scar; only obviously malignant, undifferentiated, spindle-shaped cells not capable of further characterization were seen on cytology. Preliminary experience with immunoperoxidase staining for the neural crest marker S-100 protein has been encouraging and may permit identification of these tumors on aspiration smears.     

Effects of temperature,ph, salinity,and inorganic nitrogen on the rate of ammonium oxidation by nitrifiers isolated from wetland environments

Ammonium-oxidizing bacteria were examined in two wetland environments, a freshwater marsh and an estuarine bay, during a 2-year period. Two predominant types were consistently isolated, one from each environment. Both isolates were identified as species ofNitrosomonas. Using a closed culture, high cell density assay, the effects of temperature, pH, salinity, Na⁺, K⁺, nitrite, nitrate, and ammonium concentrations on ammonium oxidation were determined. Maximum activity was observed for the freshwater isolate at 35°C, pH 8.5, salinities of 0.3 to 0.5% Na⁺ and K⁺, and ammonium concentrations greater than 0.5 g/l. For the estuarine isolate, maximum activity was observed at 40°C, pH 8.0, salinities of 0.5 to 1.0%, 1.0% Na⁺ and K⁺, and 0.2 g/l ammonium. The estuarine isolate had a Na⁺ requirement which could be partially substituted by the K⁺, suggesting that the organism is a true estuarine bacterium. Nitrite inhibited both isolates at concentrations greater than 5 mg/l, whereas nitrate had no significant effect on either isolate.     

Peptide map comparisons of epidermal and spleen H-2 molecules

Peptide map comparisons of molecules encoded in the mouseH-2 complex isolated from epidermal cell preparations have been carried out. We previously showed that the Ia molecules from both theI-A andI-E subregions are synthesized by nonlymphoid bone-marrow-derived cells, probably Langerhans cells. The K and D or transplantation molecules are synthesized by both true epidermal cells and nonlymphoid bone-marrow-derived cells. The tryptic maps generated by separating tryptic peptides by high pressure liquid chromatography (HPLC) of epidermal H-2 molecules are identical to their spleen-cell counterparts. The biological significance of this finding is discussed.