Nuclear and Mitochondrial DNA Polymorphisms in three parthenogenetic meloidogyne SPP

In order to expand our understanding of the genetics of root-knot nematodes, thevariation in nuclear DNA and mitochondrial DNA in Meloidogyne incognita, M.arenaria and M. javanica was investigated. Despite the obligate mitoticparthenogenetic mode of reproduction, a large number of AFLP polymorphismswere observed among all 16 populations studied. Both UPGMA and principlecoordinate analyses revealed three distinct groups that corresponded with therespective species identities of the 16 populations. M. incognita was geneticallymost distinct. Amplification of 63 bp tandem repeats (TR) in mtDNA from singleindividuals enabled the calculation of diversity measures at three hierarchicallevels: within individuals, among individuals of a single population and amongpopulations. For all three species, the highest diversity was observed withinindividuals explaining 43 to 65% of the total diversity. Many individualscontained more than one mtDNA size variant. M. incognita harboured the mostheteroplasmic individuals and was the most homogenous at the population level.Only 13% of the total diversity was observed among populations, while thisfigure was 35% for M. arenaria. Both TR and AFLP data showed that M.arenaria is the most heterogeneous species. The comparison of the geneticdistances based on AFLPs and mtDNA size variants revealed a significantcorrelation for the six M. arenaria populations, whereas no consistent correlationwas observed for the populations of the other two species

Meloidogyne spp. во Македонија: дистрибуција и вирулентност за Mi резистентност во домати

Појавата на Meloidogyne во неколку области во Македонија беше испитувана. Седумдесет и три исолати од 9 локации (полски и оранжериски) беа идентификувани и нивното однесување кон две осетливи и две Mi-отпорни доматни сорти беше испитувано. M. incognita (47,9) и M. javanica (35,6%) беа предоминантни видови, додека М. аренариа (13,7%) беше поретко застапена, а M. hapla беше детектирана спорадично. Во скоро сите локации е утврдено присуство на повеќе од еден вид. Вирулентни изолати беа најдени во M. incognita (11%), M. javanica (46%) како и во M. arenaria (50%). M. hapla изолатите беа компатибилни со сите испитувани генотипови од доматот. Влијанието на присуството на вирулентни популации за Mi-генотипови на домати е дискутирано

Serological Differentiation of Plant-parasitic Nematode Species with Polyclonal and Monoclonal Antibodies

Although several attempts have been made to differentiate nematode species with polyclonal antisera, these efforts thus far have met with limited success because of extensive crossreactivities of the sera. Since the hybridoma technique offers the opportunity to develop more specific serological reagents, some research groups have recently started to apply this technology to the problem of species identification in nematology. Monoclonal antibodies (MA) that differentiate the potato-cyst nematodes Globodera rostochiensis and G. pallida, as well as MA specific for Meloidogyne species, have been developed. The possibilities of developing serodiagnostic tools for identification of nematodes recovered from soil samples and the implications of such monitoring of nematode infestations in view of integrated control of plant-parasitic nematodes are discussed

β-d-glucosyl-hydroxymethyluracil: A novel modified base present in the DNA of the parasitic protozoan T. brucei

We have previously shown that the DNA of the unicellular eukaryote T. brucel contains about 0.1% of a novel modified base, called J. The presence of J correlates with a DNA modification associated with the silencing of telomeric expression sites for the variant surface antigens of trypanosomes. Here we show that J is 5-((β-d-glucopyranosyloxy)-methyl)-uracil (shortened to β-d-glucosyl-hydroxymethyluracil), a base not previously found in DNA. We discuss putative pathways for the introduction of this base modification at specific positions in the DNA and the possible contribution of this modification to repression of surface antigen gene expression. © 1993

Endogenous cellulases in animals: Isolation of β-1,4-endoglucanase genes from two species of plant-parasitic cyst nematodes

β-1,4-Endoglucanases (EGases, EC 3.2.1.4) degrade polysaccharides possessing β-1,4-glucan backbones such as cellulose and xyloglucan and have been found among extremely variegated taxonomic groups. Although many animal species depend on cellulose as their main energy source, most omnivores and herbivores are unable to produce EGases endogenously. So far, all previously identified EGase genes involved in the digestive system of animals originate from symbiotic microorganisms. Here we report on the synthesis of EGases in the esophageal glands of the cyst nematodes Globodera rostochiensis and Heterodera glycines. From each of the nematode species, two cDNAs were characterized and hydrophobic cluster analysis revealed that the four catalytic domains belong to family 5 of the glycosyl hydrolases (EC 3.2.1, 3.2.2, and 3.2.3). These domains show 37–44% overall amino acid identity with EGases from the bacteria Erwinia chrysanthemi, Clostridium acetobutylicum, and Bacillus subtilis. One EGase with a bacterial type of cellulose-binding domain was identified for each nematode species. The leucine-rich hydrophobic core of the signal peptide and the presence of a polyadenylated 3′ end precluded the EGases from being of bacterial origin. Cyst nematodes are obligatory plant parasites and the identified EGases presumably facilitate the intracellular migration through plant roots by partial cell wall degradation