Genetic polymorphism at the mouse immunoglobulin J ϰ locus (Igk-J) as demonstrated by southern hybridization and nucleotide sequence analysis

Comparison of the nucleotide sequences of the C.C58 M75 myeloma chain gene and the BALB/c germ-line J segments suggested that the J regions of C.C58 and BALB/c might be distinguished by restriction enzyme polymorphisms. This was shown to be the case in Southern hybridizations of Hinf I and Ace I digests of liver DNA from these and other strains with a J-specific probe. Tests of a wide variety of inbred, congenic, recombinant, and recombinant-inbred strains provided evidence for three alleles, Igk-J ^a, Igk-J ^b, and Igk-J ^c, the type strains for which are C58/J, BALB/c, and SJL/J, respectively. Analysis of the B6.PL(85NS) congenic strain suggests that the Igk-J locus lies in the neighborhood of the Lyt-2/Lyt-3 loci, approximately 0.30 cM from the V gene segment determining the Igk-VSer and Igk-Efl polymorphisms. Finally, nucleotide substitutions lead to amino acid sequence differences between the C.C58 M 75 gene and the BALB/c germ line in J2 and J4. Two of these substitutions reflect true germ-line differences, raising the possibility that idiotype differences observed among strains could reflect J as well as V differences.     

Body size effects and rates of cytochrome b evolution in tube-nosed seabirds

Variation in rates of molecular evolution now appears to be widespread. The demonstration that body size is correlated with rates of molecular evolution suggests that physiological and ecological factors may be involved in molecular rate variation, but large-scale comparative studies are still lacking. Here, we use complete cytochrome b sequences from 85 species of tube-nosed seabirds (order Procellariiformes) and 5 outgroup species of penguins (order Sphenisciformes) to test for an association between body mass and rates of molecular evolution within the former avian order. Cladistic analysis of the 90 sequences estimates a phylogeny largely consistent with the traditional taxonomy of the Procellariiformes. The Diomedeidae, Procellariidae, and Pelecanoididae are monophyletic, while the Hydrobatidae are basal and paraphyletic. However, the two subfamilies within the Hydrobatidae (Hydrobatinae and Oceanitinae) are monophyletic. A likelihood ratio test detects significant deviation from clocklike evolution in our data. Using a sign test for an association between body mass and branch length in the seabird phylogeny, we find that larger taxa tend to have shorter terminal branch lengths than smaller taxa. This observation suggests that rates of mitochondrial DNA evolution are slower for larger taxa. Rate calibrations based on the fossil record reveal concordant body size effects. We interpret these results as evidence for a metabolic rate effect, as the species in this order exhibit large differences in metabolic rates, which are known to be highly correlated with body mass in this group. Our results support previous findings of body size effects and show that this effect can be significant even within a single avian order. This suggests that even lineage-specific molecular clocks may not be tenable if calibrations involve taxa with different metabolic rates.      

Molecular evolution of chloroplast DNA sequences

Comparative data on the evolution of chloroplast genes are reviewed. The chloroplast genome has maintained a similar structural organization over most plant taxa so far examined. Comparisons of nucleotide sequence divergence among chloroplast genes reveals marked similarity across the plant kingdom and beyond to the cyanobacteria (blue-green algae). Estimates of rates of nucleotide substitution indicate a synonymous rate of 1.1 x 10(-9) substitutions per site per year. Noncoding regions also appear to be constrained in their evolution, although addition/deletion events are common. There have also been evolutionary changes in the distribution of introns in chloroplast encoded genes. Relative to mammalian mitochondrial DNA, the chloroplast genome evolves at a conservative rate.      

Glycerokinase in rat and human adipose tissue: response to hormonal and dietary stimuli.

Glycerokinase activity was measured in homogenates of rat and human adipocytes. Human adipocyte glycerokinase activity was not altered by various dietary and hormonal treatments. In contrast, glycerokinase activity in rat adipocytes was decreased by fasting 48 hr and returned toward normal levels after refeeding for 36 hr. This increase in enzyme activity during refeeding was blocked by prior administration of uromycin. Glycerokinase activity was also significantly increased following prolonged incubation of rat adipocytes with dexamethasone in vitro. This stimulation of glycerokinase was further augmented by the simultaneous addition of insulin. Glycerokinase activity in rat and human adipocytes was also dependent on the body weight of the respective tissue donor. Other data presented indicate that glycerokinase is not involved in the "anti-lipolytic" action of insulin. The possible metabolic significance of glycerokinase in adipose tissue is discussed.     

<i>Trichoderma</i> spp. fostering growth on <i>Capsicum chinense</i> Jacq. seedlings and antagonistic against <i>Meloidogyne incognita</i>

Fourteen native strains of Trichoderma spp. from wildand agricultural pathosystems in the state of Yucatan, Mexico, with growth-promoting ability of Capsicum chinense Jacq. seedlings were evaluated and antagonistic effect of their filtrate against second-stage juveniles (J2) of Meloidogyne incognita. The strains Th05-02 and Th27-08 showed the best significant effects on plant hight variable increments 55.57 and 47.62%, theTh07-04 with 29.48% more root length, theTh02-01 and Th07-04 isolates increased from 48.71 to 84.61% in volume radical and 53.40% of total dry biomass. Statistical analysis (p≤0.001) of Th43 and Th43-13-14 filtrates caused 100% mortality at 24 and 48h. In the test of reversibility to 24 h after replacing the filtrates Th43-13, Th43-14, TH09-06 and TH20-07 by sterile distilled water, the J2 did not recover their viability, so they were considered as the best potential strains of Trichoderma spp. with antagonistic capacity in J2 of M.incognita.     

Clubroot resistance QTL are modulated by nitrogen input in <Emphasis Type="Italic">Brassica napus</Emphasis>

Key message

Nitrogen levels can modulate the effectiveness of clubroot resistance in an isolate- and host-specific manner. While the same QTL were detected under high and low nitrogen, their effects were altered.

Abstract

Clubroot, caused by Plasmodiophora brassicae, is one of the most damaging diseases of oilseed rape and is known to be affected by nitrogen fertilization. However, the genetic factors involved in clubroot resistance have not been characterized under nitrogen-limiting conditions. This study aimed to assess the variability of clubroot resistance under different nitrogen levels and to characterize the impact of nitrogen supply on genetic resistance factors. Linkage analyses and a genome-wide association study were conducted to detect QTL for clubroot resistance and evaluate their sensitivity to nitrogen. The clubroot response of a set of 92 diverse oilseed rape accessions and 108 lines derived from a cross between ‘Darmor-bzh’ (resistant) and ‘Yudal’ (susceptible) was studied in the greenhouse under high- and low-nitrogen conditions, following inoculation with the P. brassicae isolates eH and K92-16. Resistance to each isolate was controlled by a major QTL and a few small-effects QTL. While the same QTL were detected under both high and low nitrogen, their effects were altered. Clubroot resistance to isolate eH, but not K92-16, was greater under a low-N supply versus a high-N supply. New sources of resistance were found among the oilseed rape accessions under both low and high-N conditions. The results are discussed relative to the literature and from a crop improvement perspective.

     

A new ant genus from the Greater Antilles and Central America,Zatania (Hymenoptera: Formicidae), exemplifies the utility of male and molecular character systems

The ant genus Prenolepis (Hymenoptera: Formicidae) is the nominal member of the recently established Prenolepis genus‐group within the subfamily Formicinae. Our molecular phylogenetic analyses using fragments from five nuclear genes (arginine kinase, carbomoylphosphate synthase, elongation factor 1‐alpha F1, elongation factor 1‐alpha F2, wingless) and one mitochondrial gene (cytochrome oxidase I) indicate that this genus is polyphyletic. Although the majority of Prenolepis species was found to belong to the same monophyletic group (Prenolepis sensu stricto), a smaller subset of Prenolepis species, all found in either Central America or the Greater Antilles, was robustly inferred to comprise a distinct lineage that is sister to the Old World genus Paraparatrechina. Here we describe this newly discovered lineage within the larger Prenolepis genus‐group clade. The genus Zatania, gen.n. is composed of five extant species (Zatania albimaculata, Zatania cisipa, Zatania gibberosa, Zatania gloriosa, sp.n. and Zatania karstica) and one Dominican amber fossil species (Zatania electra^?, sp.n. ). These are medium‐sized ants (generally between 2.5 and 3 mm in total length) that are characterized by having long scapes and legs, and elongated mesosomata. A reliance on worker‐based taxonomy has previously prevented the discovery of this new lineage because of worker convergence consisting of various combinations of elongated mesosomata, long scapes and legs, and a constriction immediately behind the pronotum, observed in several distinct lineages within the Prenolepis genus‐group. However, we did find that male morphology complements our molecular results in revealing important diagnostic and potentially phylogenetically informative characters. Our study highlights the value for ant systematics to expand beyond its traditional foundation of worker‐based morphology and embrace character systems from other castes and molecular data.     

Non-steroidal dissociated glucocorticoid agonists: indoles as A-ring mimetics and function-regulating pharmacophores

We report a SAR of non-steroidal glucocorticoid mimetics that utilize indoles as A-ring mimetics. Detailed SAR is discussed with a focus on improving PR and MR selectivity, GR agonism, and in vitro dissociation profile. SAR analysis led to compound (R)-33 which showed high PR and MR selectivity, potent agonist activity, and reduced transactivation activity in the MMTV and aromatase assays. The compound is equipotent to prednisolone in the LPS-TNF model of inflammation. In mouse CIA, at 30 mg/kg compound (R)-33 inhibited disease progression with an efficacy similar to the 3 mg/kg dose of prednisolone.