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Biomedical subjects

J T Wood

Publications and source records attributed to J T Wood.

8 recordsLinked to original sources
PubMed2006

The variable codons of H3 influenza A virus haemagglutinin genes.

We have analyzed several sets of well-studied haemagglutinin (HA) gene sequences of H3 subtype influenza A viruses to identify codons that are unusually variable, using a simple pairwise sliding window method, DnDscanning. For two of the sets there were results of detailed phylogenetic modeling studies of selection already published. A third set had been the subject of an antigen mapping study, the results of which provide a completely independent benchmark of selected changes in H3 HA genes. Our analyses show that the codons with greatest DnDscan scores (i.e. the most variable) were mostly those reported in the published studies as being positively selected; indeed the DnDscan results matched the antigenic mapping results more closely than did those of the phylogenetic modeling methods. These results suggest that codons under selection can be found even when, as with some sets of virus sequences, a phylogeny is uncertain or cannot be obtained because, for example, the sequences are recombinants, or when selection is not necessarily linked with phylogeny, as in host-switching events. The program DnDscan is available at (biojanus.anu.edu.au).

Algorithms↗
PubMed2005

Marker-based quantitative genetics in the wild?: the heritability and genetic correlation of chemical defenses in eucalyptus.

Marker-based methods for estimating heritability and genetic correlation in the wild have attracted interest because traditional methods may be impractical or introduce bias via G x E effects, mating system variation, and sampling effects. However, they have not been widely used, especially in plants. A regression-based approach, which uses a continuous measure of genetic relatedness, promises to be particularly appropriate for use in plants with mixed-mating systems and overlapping generations. Using this method, we found significant narrow-sense heritability of foliar defense chemicals in a natural population of Eucalyptus melliodora. We also demonstrated a genetic basis for the phenotypic correlation underlying an ecological example of conditioned flavor aversion involving different biosynthetic pathways. Our results revealed that heritability estimates depend on the spatial scale of the analysis in a way that offers insight into the distribution of genetic and environmental variance. This study is the first to successfully use a marker-based method to measure quantitative genetic parameters in a tree. We suggest that this method will prove to be a useful tool in other studies and offer some recommendations for future applications of the method.

Australian Capital Territory↗
PubMed1983

Haematology of Indonesian large ruminants.

Haematology parameters were measured in buffalo, Bali, Madura, Ongole and Grati (Friesian cross) bulls fed on either a high concentrate or a high roughage-based diet. Animals fed the high concentrate diet had the higher packed cell volumes and haemoglobin concentrations but lower red blood cell and white blood cell counts. Species differences were significant for all blood parameters measured, except red blood cell count. The buffalo and Bali had the highest packed cell volumes, haemoglobin concentrations and white blood cell counts followed by the Madura, Ongole and Grati bulls. When growth rate and feed efficiency were related to liveweight and blood values, only haemoglobin concentration and red blood cell count had significant partial regression coefficients. Within breed or species blood and performance parameters were significantly related only for buffalo and Madura bulls.

Animals↗
PubMed1981

Changes of aging parameters among rats on diets differing in fat quantity and quality.

Portion rats in a life span study were fed three diets which differed in the quantity and quality of total fats but were supplied in calorically equal amounts. In an attempt to comparing aging rates, we used a combination of tests involving different organ systems. This holistic approach to measuring aging included the assessment of changes in multifactorially regulated systems of glucose homeostasis and oxygen consumption; changes in tension responses of the extracellular protein collagen and accumulation of lipofuscin pigment in adrenal glands were also measured. Glucose tolerance and oxygen consumption changed in age largely as expected and there were no consistent differences between the aging rates for the three different diets. Accumulation of the intracellular aging pigment lipofuscin and the breaking time of tail tendons also showed the expected increases with increasing age. Dietary differences were noted with the 2-year-old rats consuming the low fat stock diet showing the greatest accumulation of lipofuscin and the longest tail tendon breaking times.

Adrenal Glands↗
PubMed1979

Aspergillus nidulans as a test organism for assessing radio-induced chromosomal non-disjunction.

A genetically marked heterozygous diploid of Aspergillus nidulans was synthesized and the feasibility of using this system for the simultaneous estimation of radio-induced mitotic crossing-over and non-disjunction has been investigated. In the case of the latter, serious experimental problems have been encountered. Nevertheless, induction curves for non-disjunction with 15-MeV electrons, 50-kVp X-rays, beta-particles and alpha-particles are presented showing an increase in non-disjunction with increasing LET.

Aspergillus nidulans↗