Use of tissue culture to bypass wheat hybrid necrosis

Summary Hybrid necrosis in wheat is a barrier to gene transfer in wheat breeding practice. It is based on two complementary genes, Ne1 and Ne2. Recovery mutants (Re1, Re2 and Re3) which can grow to maturity were recovered from immature embryo cultures of necrotic hybrids between T. aestivum and T. durum. Cytological observation demonstrated that Re1 had 34 chromosomes instead of 35. This indicated that one of the chromosomes carrying the Ne genes was lost. Genetic study suggested that for Re1, the lost chromosome was chromosome 5B of the durum parental line. Re mutants are male sterile but can be maintained through a young ear culture method. Re mutants could be successfully pollinated by either parental line and the BC1 progeny is partially fertile. Re mutants were repeatedly induced in about 1% of the regenerated plants from immature embryo culture. This technique provides a practical way to bypass hybrid necrosis.     

Evaluation of the ability to solve the Revecz-Krushinski? test in corvine birds

Reasoning ability in crows was investigated by means of the Revecz-Krushinski? test, in which the bird has to apprehend the rule of stimulus (food bait) displacement: "In each next trial the food bait is hidden in a new place--one step further along the row". By means of computer modelling the criteria of statistical evaluation of this problem solving were established. The test was considered solved when the number of trials which preceded the detection of food was less than those which were calculated for chance performance. High level of reasoning ability in crows is discussed.     

The inhibition of succinate, beta-oxybutyrate and glutamate transport in the liver mitochondria of hibernating susliks

Studies have been made on the permeability of the inner membrane of the liver mitochondria from hibernating and active ground squirrels for succinate, glutamate, hydroxybutyrate and inorganic phosphate. The permeability was calculated from the rate of mitochondrial swelling in 100 mM ammonium salts of the substrates and phosphate. It was shown that the rate of mitochondrial swelling in hibernating animals is 2--3 times lower than in active ones, being essentially identical in a solution of ammonium phosphate. It was concluded that the permeability of the inner mitochondrial membrane for the substrates decreases in hibernating animals, remaining unaffected for phosphate. Calcium-induced activation of membrane phospholipase A2 facilitates the transport of oxidative substrates into the mitochondria of hibernating ground squirrels, significant increase in the mitochondrial respiration being simultaneously observed. The data obtained suggest that inhibition of transport of oxidative substrates is one of the main factors which account for a low respiration rate in the mitochondria of hibernating animals.     

Phospholipid composition of plasma and erythrocytes in the neonate

The total phospholipids and their various classes in erythrocytes and blood plasma were determined quantitatively by means of two-dimensional thin-layer chromatography. The total amount of phospholipids in neonate plasma was approximately half of that found in adult plasma, however, the amount of phospholipids in erythrocytes of the neonate was significantly higher. The differences were observed in some classes of phospholipids in the plasma and erythrocytes of neonates as well as adult human beings.     

Military antishock garment reevaluated

In Los Angeles, a substantial increase in the number of infections due to Neisseria meningitidis has been noted. More alarming has been an associated mortality rate of 21%. The prompt recognition of meningococcal disease based on a high index of suspicion and the early institution of effective antibiotic treatment are essential for preventing complications and reducing mortality.     

Drosophila neuroglian: a member of the immunoglobulin superfamily with extensive homology to the vertebrate neural adhesion molecule L1

Drosophila neuroglian is an integral membrane glycoprotein that is expressed on a variety of cell types in the Drosophila embryo, including expression on a large subset of glial and neuronal cell bodies in the central and peripheral nervous systems and on the fasciculating axons that extend along them. Neuroglian cDNA clones were isolated by expression cloning. cDNA sequence analysis reveals that neuroglian is a member of the immunoglobulin superfamily. The extracellular portion of the protein consists of six immunoglobulin C2-type domains followed by five fibronectin type III domains. Neuroglian is closely related to the immunoglobulin-like vertebrate neural adhesion molecules and, among them, shows most extensive homology to mouse L1. Its homology to L1 and its embryonic localization suggest that neuroglian may play a role in neural and glial cell adhesion in the developing Drosophila embryo. We report here on the identification of a lethal mutation in the neuroglian gene.     

The occurrence of endotoxin in sows with coliform mastitis

The purpose of this study was to determine the role of endotoxins in the etiology of coliform mastitis /CM/ in sows under field conditions, by using the Limulus amebocyte lysate /LAL/ test for the detection of endotoxins in the blood of pigs. For this purpose, blood samples from 40 healthy sows and 46 sows with clinical signs of CM were drawn once between 24 and 72 h post partum and tested accordingly. Only one clinically healthy sow 2.5% showed the presence of endotoxins in the serum. In sows clinically affected with one or more symptoms of the CM, the bacterial toxins were detected in 15 cases /32.5%/. The results of these studies support the observation that in only a certain percentage of all CM cases the occurrence of endotoxin in blood can be shown. Sampling time in relation to the occurrence of clinical symptoms and sampling frequency may have had an influence on the detectability of circulating endotoxins. Consequently, not all cases with endotoxemia may have been identified. The usefulness of the LAL test for endotoxin detection in the blood of pigs was confirmed.     

Homologous plasmid recombination is elevated in immortally transformed cells.

The levels of intramolecular plasmid recombination, following transfection of a plasmid substrate for homologous recombination into normal and immortally transformed cells, have been examined by two independent assays. In the first assay, recovered plasmid was tested for DNA rearrangements which regenerate a functional neomycin resistance gene from two overlapping fragments. Following transformation of bacteria, frequencies of recombinationlike events were determined from the ratio of neomycin-resistant (recombinant) colonies to ampicillin-resistant colonies (indicating total plasmid recovery). Such events, yielding predominantly deletions between the directly repeated sequences, were substantially more frequent in five immortal cell lines than in any of three normal diploid cell strains tested. Effects of plasmid replication or interaction with T antigen and of bacterially mediated rejoining of linear molecules generated in mammalian cells were excluded by appropriate controls. The second assay used limited coamplification of a control segment of plasmid DNA, and of the predicted recombinant DNA region, primed by two sets of flanking oligonucleotides. Each amplified band was quantitated by reference to a near-linear standard curve generated concurrently, and recombination frequencies were determined from the ratio of recombinant/control DNA regions. The results confirmed that recombinant DNA structures were generated within human cells at direct repeats in the transfected plasmid and were markedly more abundant in an immortal cell line than in the diploid normal cells from which that line was derived.     

Enhancement of major histocompatibility class I protein synthesis by DNA damage in cultured human fibroblasts and keratinocytes.

Exposure of primary human fibroblasts or simian virus 40-transformed human keratinocytes to several different classes of DNA damage, including UV light C (254 nm), resulted in a rapid increase in the expression of human major histocompatibility class I (MHC-I) proteins. MHC-I induction was also detected after exposure to low doses of the protein synthesis inhibitor cycloheximide, suggesting that MHC-I induction by DNA damage may be a component in a derepressible cellular SOS pathway.