Molecular Characterization of a Barley Gene Induced by Cold Treatment

A cDNA library was made from low positive temperature (6 ?C/2?C) grown barley shoot meristems. Several genes which are differentiallyexpressed, as measured by mRNA abundance, were selected fromthe library using a differential screen. This paper reportsan analysis of in vivo expression in several cultivars, theDNA sequence, copy number and chromosomal location of one gene(BLT14). In addition, genomic restriction fragment length polymorphismfor this gene in the 10 most widely UK-grown spring and 9 mostwidely UK-grown winter barley cultivars is analysed. Key words: Hordeum vulgare, low temperature, RFLP, differential expression, cDNA sequence     

Subdivision of equine Tf into H1 and H2

Subdivision of equine TfH into two variants, designated H1 (faster) and H2 (slower), has been accomplished by high voltage, thin layer polyacrylamide gel electrophoresis at pH 7.9. Transferrin H1 and H2 have been shown to be controlled by codominant alleles and gene frequencies of the Tf alleles have been determined in the Australian Thoroughbred, Standardbred. Quarter Horse and Arabian Horse breeds.     

The Production of Leaves and Stolon Branches on Established White Clover Cuttings in Relation to Temperature and Soil Moisture in the Field

Successive sets of cuttings of three white clover genotypeswere raised in a 15 °C growth room and transferred to thefield at 14 d intervals over the course of a year. Rates ofleaf appearance (leaves per stolon growing point per unit time)were found to be closely correlated with 10 cm soil temperatures.Petiole lengths, and weights of the lamina+petiole increasedin May and decreased towards the end of August, but also exhibiteda marked response to a mid-season water deficit. In the conditionsof the experiment (i.e. in the absence of competition from neighbouringplants) the vast majority of axillary buds developed into visiblebranches at all times of the year. There was, however, an increasein the nodal age at which bud development was first observedin winter. Deferred bud development was also observed, particularlyin one genotype, during periods characterized by dry soil surfaceconditions. The results are discussed in relation to observedpatterns of stolon branching in sward conditions. White clover, Trifolium repens, axillary bud development, branching, growing points, leaf appearance rate, petiole length, soil moisture, soil temperature     

Expansion of the canine A blood group system

A detailed study of the canine A blood group system was undertaken, resulting in the expansion of this system into a three-factor, four-allelic one with the recognition of an additional subtype, a3. The serological and extensive family data supported the proposed genetic theory of four alleles with dominance with the order being Aa1, Aa2, Aa3 and A-. Gene frequencies of the alleles were determined in various breeds of dogs with frequencies in the general Brisbane population being 0.244 (Aa1), 0.042 (Aa2), 0.045 (Aa3) and 0.669 (A-).     

An Evaluation of EPR Measurements of the Organic Free Radical Content of Individual Seeds in the Non-destructive Testing of Seed Viability

Hepburn, H. A., Goodman, B. A., McPhail, D. B., Matthews, S.and Powell, A. A. 1986. An evaluation of EPR measurements ofthe organic free radical content of individual seeds in thenon-destructive testing of seed viability.—J. exp. Bot.37: 1675–1684. Electron paramagnetic resonance (EPR) spectra of individualintact seeds of a range of legumes and brassicas have been obtainedin order to measure their organic free radical contents. Norelationship was found between free radical content and seedviability or early seedling growth for both legumes and brassicas.The testa had a much greater free radical concentration thaneither the embryo axes or the cotyledons for all cultivars ofseed tested. The general high free radical content of the testasuggests that there is little possibility of EPR being usedto predict the viability of individual seeds. The spectroscopicsplitting factor of g = 2·0045 reported for the intactseeds is consistent with the radicals' arising from melanictype compounds. Key words: Seed viability, free radical content     

Vertical community structure and resource utilization in neotropical forest cockroaches

ABSTRACT.

• 1 Patterns of vertical habitat use of ten species of cockroaches are examined. Three assemblages of cockroaches are recognized on the basis of morphology, foraging behaviour, foraging heights, and overlaps and breadths of vertical distributions.
• 2 Three apterous and brachypterous species occur near the ground and comprise one assemblage. They feed mainly on material in the leaf-litter.
• 3 Species that perch higher either migrate into the leaf-litter on a diel basis and feed on both leaf-litter and epiphyllic materials, or some are strictly arboreal and forage on algae, liverworts, lichens, spores, pollen and trichomes on the surfaces of leaves.
• 4 Trophic and behavioural correlations with perch height are described and the functions of perching are examined.
• 5 We conclude that studies of interactions among species are confounded by our lack of understanding of stage- and sex-specific interactions of coexisting species. A simplistic ‘species’approach to such interactions is inadequate because it does not recognize intraspecific variation.

     

The life-history of the leaf-curling plum aphid Brachycaudus helichrysi in Northern Ireland and its ability to transmit potato virus YC(AB)

The life-history of leaf-curling plum aphid, Brachycaudus helichrysi was studied in Northern Ireland from 1977–1980. It was shown that the life cycle differed in several respects from those of geographically distinct populations, reported by other authors, especially with regard to the timing of egg hatch. Body length and antennal segment measurements of the adult stages on Prunus spinosa and Trifolium pratense correlated well with published dimensions for the species. Virological studies showed B. helichrysi to be capable of transmitting potato virus Y^C(AB) with a vector efficiency of 34%. This value is higher than previous estimates and enhances the significance of the species as a virus vector in potato crops early in the growing season.     

The Importance of Genetically Determined Seed Coat Characteristics to Seed Quality in Grain Legumes

Comparisons of five pairs of isogenk lines of peas, differingonly in the A gene for seed coat colour showed that white seeds(genotype aa) imbibed more rapidly than coloured seeds (AA),suffered greater imbibition damage revealed by dead tissue onthe cotyledons, and higher solute leakage. Seed-coat pigmentationwas closely associated with slow water uptake, since when expressionof the A gene was suppressed by the recessive pollens gene,the resulting white seeds {palpal AA) imbibed rapidly. The slowwater uptake by coloured seeds was not due to the restrictionof water entry by the seed coat since the differences in imbibitionrate were maintained when a portion of the seed coat was removedand seeds were imbibed with the exposed cotyledon in contactwith moist filter paper. Imbibition of similarly treated seedsby immersion in polyethylene glycol solutions (1–4%) whichincreased the seed/solution wettability, had little effect onthe water uptake of coloured seeds compared to imbibition inwater whereas that of white seeds increased in the first 10mins imbibition. Poor wettability of the inner surface of colouredseed coats did not therefore explain the slow imbibition ofthese seeds. The white seed coats loosened rapidly during imbibitionwhilst the coloured seed coats remained closely associated withthe cotyledons suggesting that the adherence of the seed coatto the cotyledons and therefore the ease of access of waterbetween the testa and cotyledons determines the rate of imbibition.The rapid water uptake by white-coated seeds and the subsequentimbibition damage may explain the high incidence of infectionof these seeds by the soil-bome fungus Pythhan after 2 d insoil. Improved seed quality and emergence may therefore be achievedby breeding for seed coat characteristics leading to reducedrates of imbibition Pisum sativum, isogenic lines, A gene, seed coat colour, imbibition, imbibition damage, wettability, pollens gene, seed quality, grain legumes