Some notes on reproduction in the Patagonian Mountain viscacha, Lagidium boxi (Mammalia: Rodentia)

The material consists of the ovaries from a pregnant female and observations on a live female of the Patagonian species of Mountain viscacha (Lagidium boxi). The study is reported because it shows that L. boxi, like the Peruvian Mountain viscacha (JL. peruanum), appears to ovulate only from the right ovary (Pearson, 1949). Features of the material are compared with information known for other hystricomorph rodents.     

Ancient diversity and geographical sub-structuring in African buffalo Theileria parva populations revealed through metagenetic analysis of antigen-encoding loci

An infection and treatment protocol involving infection with a mixture of three parasite isolates and simultaneous treatment with oxytetracycline is currently used to vaccinate cattle against Theileria parva. While vaccination results in high levels of protection in some regions, little or no protection is observed in areas where animals are challenged predominantly by parasites of buffalo origin. A previous study involving sequencing of two antigen-encoding genes from a series of parasite isolates indicated that this is associated with greater antigenic diversity in buffalo-derived T. parva. The current study set out to extend these analyses by applying high-throughput sequencing to ex vivo samples from naturally infected buffalo to determine the extent of diversity in a set of antigen-encoding genes. Samples from two populations of buffalo, one in Kenya and the other in South Africa, were examined to investigate the effect of geographical distance on the nature of sequence diversity. The results revealed a number of significant findings. First, there was a variable degree of nucleotide sequence diversity in all gene segments examined, with the percentage of polymorphic nucleotides ranging from 10% to 69%. Second, large numbers of allelic variants of each gene were found in individual animals, indicating multiple infection events. Third, despite the observed diversity in nucleotide sequences, several of the gene products had highly conserved amino acid sequences, and thus represent potential candidates for vaccine development. Fourth, although compelling evidence for population differentiation between the Kenyan and South African T. parva parasites was identified, analysis of molecular variance for each gene revealed that the majority of the underlying nucleotide sequence polymorphism was common to both areas, indicating that much of this aspect of genetic variation in the parasite population arose prior to geographic separation.     

Toxigenic bacteria and sudden infant death syndrome (SIDS): nasopharyngeal flora during the first year of life

Many developmental and environmental risk factors for sudden infant death syndrome (SIDS) are similar to those for susceptibility to respiratory tract infection, and toxigenic bacteria have been implicated in some SIDS cases. We assessed nasopharyngeal flora of healthy infants in relation to risk factors to determine which species best lit the mathematical model proposed for the common bacterial toxin hypothesis and if these findings complemented results obtained from SIDS cases which occurred during the period of the survey. Longitudinal studies were carried out between April 1993 and March 1996 on 253 healthy infants and their mothers. 150 from a multiply deprived area, 103 from an affluent area. Concurrent SIDS infants (37) were screened for nasopharyngeal flora. Among healthy infants < or = 3 months of age, the predominant isolate was Staphylococcus aureus 57% compared with 86% for SIDS infants in that age range (P< 0.02). There were significant associations between isolation of different species from both mother and baby but no association between isolation of any species with: area of residence: parental smoking habits; breast or bottle feeding; symptoms of viral infection: seasonality. We conclude that S. aureus fits the mathematical model for SIDS. Both staphylococci and/or their toxins were identified in a significant proportion of SIDS cases. Isolation of staphylococci from healthy infants was associated with the 2-4-month age range, a risk factor consistently found in all epidemiological studies of SIDS. This might reflect the developmental stage in which 80-90% of infants express the Lewis(a) antigen which we have shown to be one of the receptors for S. aureus.     

Descent measures for two loci with some applications

For any four genes, two at each of two loci, in a population, a 15 component descent measure has been introduced. These components are the probabilities of the 15 possible arrangements on a set of initial gametes of those genes of which the four of interest are copies. Since identity by descent of genes is equivalent to their being copies of a single gene on an initial gamete, descent measures have inbreeding coefficients as special cases. The individual descent measure, defined for four genes on two uniting gametes can be evaluated for any pedigree by means of an algorithm developed here. If initial gametic frequencies are specified, descent measures allow genotypic frequencies and disequilibria functions at one and two loci to be found. The procedures are illustrated for selfing and for sib mating. Several applications of the descent measures are discussed.     

Phytotoxic polyacetylenes from roots of Russian knapweed (Acroptilon repens (L.) DC.)

There are several factors thought to assist invasive weeds in colonization of ecosystems. One of these factors is allelopathy, the negative effect of chemicals produced by one plant on neighboring plants, frequently mediated through root exudates and other plant leachates. Acroptilon repens (Asteraceae) is one of the most invasive and ecologically threatening weed species in western North America. A bioassay-guided fractionation of the root extracts of this plant led to the isolation of five polyacetylenic compounds, of which one [5′-methoxy-1′-(5-prop-1-yn-1-yl-2-thienyl)-hexa-2′,4′-diyin-6′-yl acetate] was hitherto unknown. The structures of these compounds were elucidated on the basis of spectroscopic analysis (IR, ESIMS, ¹H, ¹³C NMR and 2D NMR). All of the compounds obtained, except 1-chloro-4-(5-penta-1,3-diyn-1-yl-2-thienyl)but-3-yn-2-ol, showed phytotoxic activity against Arabidopsis thaliana seedlings. The presence of 4′-chloro-1′-(5-penta-1,3-diyn-1-yl-2-thienyl)-but-2′-yn-3′-ol was detected in the root exudates of aeroponically grown A. repens plants. None of the polyacetylenes isolated in this study were found in Colorado soils collected between September 2006 and July 2007 in an A. repens colonized site. However, polyacetylene 5 in A. repens infested soil from Washington was found in June, 2007. Contrary to our previous report, the compound 7,8-benzoflavone (6) was not detected in root exudates, nor was it encountered in extracts of roots, aerial parts or infested soil. Since we could not repeat this work, the original report has been retracted [Stermitz, F.R., Bais, H.P., Foderaro, T.A., Vivanco, J.M., 2003. 7,8-Benzoflavone: a phytotoxin from root exudates of invasive Russian knapweed [A retraction]. Phytochemistry 64, 493-497.].