The usage of marker traits in plants for evaluation of resistance of the winter wheat to pest insects

A new method of selection of the winter wheat varieties has been tested for resistance to the pest insects' complex by the traits of plants that are the markers of plant resistance. It makes it possible to use this method from year to year independently of the pests' density.     

Protective immune mechanisms against Theileria parva: evolution of vaccine development strategies.

Theileria parva is an intracellular sporozoan parasite that infects and transforms bovine lymphocytes, causing a severe lymphoproliferative disease known as East Coast fever in eastern, central and southern Africa. In this article, Declan McKeever and colleagues summarize the current understanding of immune mechanisms provoked by the parasite with regard to their role in both pathogenesis and protection. In particular, the influence of genomic polymorphism in parasite and host on the development of immunity is discussed, along with the evolution of current vaccine development strategies as a result of immunological research on the disease.     

Immune responses to Cowdria ruminantium infections.

Understanding the basis of protective immunity to Cowdria ruminantium will facilitate the development of an effective subunit vaccine against heartwater in ruminants and contribute to a better definition of protective immune mechanisms to obligate intracellular pathogens in general. Until recently, immunological studies of heartwater in ruminants concentrated solely on antibody responses. Since 1995, the mechanisms underlying cell-mediated immunity of heartwater have been analysed. Progress achieved in these areas is discussed here by Philippe Totté and colleagues, with special emphasis on ruminants, the natural hosts of C. ruminantium.     

Discovery and optimization of adamantyl carbamate inhibitors of 11β-HSD1

Synthesis of 2-adamantyl carbamate derivatives of piperidines and pyrrolidines led to the discovery of 9a with an IC₅₀ of 15.2 nM against human 11β-HSD1 in adipocytes. Optimization for increased adipocyte potency, metabolic stability and selectivity afforded 11k and 11l, both of which were >25% orally bioavailable in rat.     

Trans-Species Polymorphism and Selection in the MHC Class II DRA Genes of Domestic Sheep

Highly polymorphic genes with central roles in lymphocyte mediated immune surveillance are grouped together in the major histocompatibility complex (MHC) in higher vertebrates. Generally, across vertebrate species the class II MHC DRA gene is highly conserved with only limited allelic variation. Here however, we provide evidence of trans-species polymorphism at the DRA locus in domestic sheep (Ovis aries). We describe variation at the Ovar-DRA locus that is far in excess of anything described in other vertebrate species. The divergent DRA allele (Ovar-DRA*0201) differs from the sheep reference sequences by 20 nucleotides, 12 of which appear non-synonymous. Furthermore, DRA*0201 is paired with an equally divergent DRB1 allele (Ovar-DRB1*0901), which is consistent with an independent evolutionary history for the DR sub-region within this MHC haplotype. No recombination was observed between the divergent DRA and B genes in a range of breeds and typical levels of MHC class II DR protein expression were detected at the surface of leukocyte populations obtained from animals homozygous for the DRA*0201, DRB1*0901 haplotype. Bayesian phylogenetic analysis groups Ovar-DRA*0201 with DRA sequences derived from species within the Oryx and Alcelaphus genera rather than clustering with other ovine and caprine DRA alleles. Tests for Darwinian selection identified 10 positively selected sites on the branch leading to Ovar-DRA*0201, three of which are predicted to be associated with the binding of peptide antigen. As the Ovis, Oryx and Alcelaphus genera have not shared a common ancestor for over 30 million years, the DRA*0201 and DRB1*0901 allelic pair is likely to be of ancient origin and present in the founding population from which all contemporary domestic sheep breeds are derived. The conservation of the integrity of this unusual DR allelic pair suggests some selective advantage which is likely to be associated with the presentation of pathogen antigen to T-cells and the induction of protective immunity.     

A polymorphism,R653Q,in the trifunctional enzyme methylenetetrahydrofolate dehydrogenase/methenyltetrahydrofolate cyclohydrolase/formyltetrahydrofolate synthetase is a maternal genetic risk factor for neural tube defects: report of the Birth Defects Research Group

Women who take folic acid periconceptionally reduce their risk of having a child with a neural tube defect (NTD) by >50%. A variant form of methylenetetrahydrofolate reductase (MTHFR) (677C-->T) is a known risk factor for NTDs, but the prevalence of the risk genotype explains only a small portion of the protective effect of folic acid. This has prompted the search for additional NTD-associated variants in folate-metabolism enzymes. We have analyzed five potential single-nucleotide polymorphisms (SNPs) in the cytoplasmic, nicotinamide adenine dinucleotide phosphate-dependent, trifunctional enzyme methylenetetrahydrofolate dehydrogenase/methenyltetrahydrofolate cyclohydrolase/formyltetrahydrofolate synthetase (MTHFD1) for an association with NTDs in the Irish population. One SNP, R653Q, in this gene appears to be associated with NTD risk. We observed an excess of the MTHFD1 "Q" allele in the mothers of children with NTD, compared with control individuals. This excess was driven by the overrepresentation of QQ homozygotes in the mothers of children with NTD compared with control individuals (odds ratio 1.52 [95% confidence interval 1.16-1.99], P=.003). We conclude that genetic variation in the MTHFD1 gene is associated with an increase in the genetically determined risk that a woman will bear a child with NTD and that the gene may be associated with decreased embryo survival.     

Acute lesions of the ventromedial hypothalamus reduce sympathetic activation and thermogenic changes induced by PGE1

The aim of this experiment was to evaluate the effects of an intracerebroventricular (icv) injection of prostaglandin E1 (PGE₁) on the sympathetic activation and the thermogenic changes in rats with acute lesions of the ventromedial hypothalamus (VMH). Four groups of six Sprague-Dawley male rats were anesthetized with ethyl-urethane. The firing rate of the sympathetic nerves innervating the interscapular brown adipose tissue (IBAT) and the colonic and IBAT temperatures were monitored both before and after one of the following treatments: 1) VMH lesion plus icv injection of PGE₁ (500 ng); 2) VMH lesion plus icv injection of saline; 3) sham lesion plus icv injection of PGE₁; and 4) sham lesion plus icv injection of saline. PGE₁ induced an increase in the firing rate of IBAT nerves and the colonic and IBAT temperatures. These effects were reduced by VMH lesion. The findings indicate that acute lesions of the VMH reduce the effects of PGE₁ and seem to suggest a possible role played by the VMH in the control of the sympathetic activation and the thermogenic changes during PGE₁ hyperthermia.     

Analysis of genetic diversity at the DQA loci in African cattle: evidence for a BoLA-DQA3 locus

 We describe the development of a polymerase chain reaction (PCR)-based approach for analysis of genetic diversity at the DQA loci in African Bos indicus and Bos taurus cattle. This approach, equally effective in European and Asian cattle breeds, detects the presence or absence of DQA1 and most duplicated DQA2 genes. Nucleotide and predicted amino acid sequence analysis of the highly polymorphic second exons, in addition to analysis of the locus-specific and relatively non-polymorphic transmembrane, cytoplasmic, and 3-prime untranslated regions, has provided evidence for considerable diversity between each of the duplicated DQA2 genes. Therefore, we propose the designation BoLA-DQA3 for the previously unpublished alleles at the second DQA2 locus. Fourteen distinct PCR restriction fragment length polymorphism (RFLP) patterns, each identifying families of alleles at three DQA loci, can be distinguished. Nucleotide sequence analysis of new PCR-RFLP patterns from 193 Kenyan Boran, Ethiopian Arsi (B. indicus), and Guinean N’Dama (B. taurus) cattle identified 13 DQA1 alleles within eight major allelic families, five DQA2 alleles within a single allelic family, and seven DQA3 alleles within three major allelic families. Received: 19 February 1997 / Revised: 28 February 1997