Oxytropis

Abstract: The genetic diversity of 44 rhizobial isolates from Astragalus, Oxytropis, and Onobrychis spp. originating from different geographic locations was evaluated by mapped restriction site polymorphism (MRSP) analysis of 16S rRNA genes and by PCR DNA fingerprinting with repetitive sequences (REP-PCR). A comparison of tree topologies of reference strains constructed with data obtained by MRSP and by 16S rRNA gene sequence analyses showed that the topologies were in good agreement, indicating that the MSRP approach results in reasonable estimates of rhizobial phylogeny. The isolates were distributed into 14 distinct 16S rRNA gene types clustering into three major groups which corresponded with three of the genera within the legume symbionts. Most of the isolates were within the genus Mesorhizobium. Five were identified with different genomic species nodulating Lotus spp. and Cicer arietinum. Three Astragalus isolates were classified as Bradyrhizobium, one being similar to Bradyrhizobium elkanii and another being similar to Bradyrhizobium japonicum. Six of the isolates were related to species within the genus Rhizobium. Two were similar to Rhizobium leguminosarum, and the remainder were identified as Rhizobium gallicum. DNA fingerprinting by REP-PCR revealed a high level of diversity within single 16S ribosomal DNA types. The 44 isolates were distributed into 34 REP groups. Rhizobial classification at the genus and probably also the species levels was independent of geographic origin and host plant affinity.

Abstract: The polyhydroxy alkaloid glycosidase inhibitors swainsonine [1] and calystegine B2 [6] have been identified as constituents of the seeds of the Australian plant Ipomoea sp Q6 [aff calobra] (Weir vine) by gas chromatography-mass spectrometry and by their biological activity as inhibitors of specific glycosidases This plant, which is known only from a small area of southern Queensland, has been reported to produce a neurological disorder when consumed by livestock The extract of the seeds showed inhibition of alpha-mannosidase, beta-glucosidase, and alpha-galactosidase, consistent with the presence of 1 and alkaloids of the calystegine class Histological examination of brain tissue from field cases of sheep and cattle poisoned by Weir vine showed lesions similar to those observed in animals poisoned by the swainsonine-containing poison peas (Swainsona spp) of Australia and locoweeds (Astragalus and Oxytropis spp) of North America These results indicate that Weir vine poisoning is an additional manifestation of the induced lysosomal storage disease, mannosidosis, possibly exacerbated by inhibition of the enzymes beta-glucosidase and alpha-galactosidase by calystegine B2 This is the first reported example of a single plant species capable of producing structurally distinct glycosidase inhibitors, namely, alkaloids of the indolizidine and nortropane classes

Abstract: Locoweeds (species of Oxytropis and Astragalus containing the toxin swainsonine) cause severe adverse effects on reproductive function in livestock All aspects of reproduction can be affected: mating behavior and libido in males; estrus in females; abortion/embryonic loss of the fetus; and behavioral retardation of offspring While much research has been done to describe and histologically characterize these effects, we have only begun to understand the magnitude of the problem, to define the mechanisms involved, or to develop strategies to prevent losses Recent research has described the effects of locoweed ingestion in cycling cows and ewes Briefly, feeding trials with locoweeds in cycling and pregnant cows have demonstrated ovarian dysfunction in a dose-dependent pattern, delayed estrus, extended estrous cycle length during the follicular and luteal phases, delayed conception (repeat breeders), and hydrops and abortion Similar effects were observed in sheep In rams, locoweed consumption altered breeding behavior, changed libido, and inhibited normal spermatogenesis Neurological dysfunction also inhibited normal reproductive behavior, and some of these effects were permanent and progressive In this article we briefly review the pathophysiological effects of locoweeds on reproduction