Resistance to <Emphasis Type="Italic">Thielaviopsis basicola</Emphasis> in the cultivated A genome cotton

Black root rot (BRR), incited by the soilborne pathogen Thielaviopsis basicola has the potential to cause significant economic loss in cotton (Gossypium spp.) production. Cultivated tetraploids of cotton (G. hirsutum and G. barbadense) are susceptible although resistant types have been identified in a possible tetraploid progenitor, G. herbaceum. Genetic mapping was used to detect the chromosomal locations of quantitative trait loci (QTL) that confer resistance to the BRR pathogen. A population of F₂ individuals (G. herbaceum × G. arboreum) and F_2:3 progeny families were examined. Phenotypic variation between resistant and susceptible reactions could be explained partly by three QTL. The BRR5.1, BRR9.1, and BRR13.1 QTL each explained 19.1, 10.3 and 8.5% of the total phenotypic variation, respectively. The combination of all three in a single genetic model explained 32.7% of the phenotypic variation. Comparative analysis was conducted on significant QTL regions to deduce the cotton–Arabidopsis synteny relationship and examine the correspondence between BRR QTL and Arabidopsis pathogen defense genes. Totally 20 Arabidopsis synteny segments corresponded within one of three BRR QTL regions. Each synteny segment contains many potential Arabidopsis candidate genes. A total of 624 Arabidopsis genes, including 22 pathogen defense and 36 stress response genes, could be placed within the syntenic regions corresponding to the BRR QTL. Fine mapping is needed to delineate each underlying BRR R-gene and possible Arabidopsis orthologs. Research and breeding activities to examine each QTL and underlying genes in Upland cotton (G. hirsutum) are ongoing. Chen Niu, Harriet E. Lister, and Bay Nguyen contributed equally to this work.     

Researching little-known species: the African bat Otomops martiensseni (Chiroptera: Molossidae)

Listed as 'vulnerable' by the International Union for theConservation of Nature, the molossid bat Otomopsmartiensseni occurs widely in Africa and, according to someauthorities, in Madagascar. Apart from a few known cave roosts, there are fewrecords of O. martiensseni, although around Durban, SouthAfrica, the species is common and roosts in buildings. Originally described asthree species, populations of O. martiensseni differsignificantly in size (length of forearm) between East Africa and Durban orMadagascar, but not between Durban and Madagascar. Seventeen buildings used asroosts by O. martiensseni averaged 34.5 ± 15.8years old. In the Durban area, bats entered roosts by landing andcrawling. Roost populations ranged from 7 to 29 individuals, typicallyconsisting of one adult male, several adult females and young (bats withunossified epiphyses), suggesting a harem social structure. The ratio of adultfemales to young was virtually 1:1, and among young the ratio of males:femalesaveraged 2:1. Radio-tracking showed that individuals used several day and nightroosts, and foraged widely in a landscape dominated by sugarcane and urbandevelopment. The echolocation and many social calls of O.martiensseni are readily audible to human observers, allowing anon-contact, low technology method for monitoring the local distribution andactivity of these bats. Although listed as a species of special concern inKwaZulu Natal, there these bats appear to be candidates for inclusion on a'blue' list of species, ones showing stabilized or increasedabundance. We recommend that O. martiensseni be recognizedas a 'flagship' species in the Durban area, r epresenting theresilience of nature.     

Leptin treatment increases suppressors of cytokine signaling in central and peripheral tissues.

Leptin concentrations are elevated in the majority of obese individuals raising the possibility that leptin resistance contributes to their obesity. Peripheral leptin administration for 48 h caused a several-fold increase in mRNA encoding the suppressors of cytokine signaling SOCS-3 and CIS in hypothalamus and peripheral tissues. Paradoxically, CIS and SOCS-3 mRNAs are also elevated in the leptin-deficient ob/ob mouse. Forced expression of CIS in insulinoma cells prevented transactivation mediated by leptin. Thus tissues continuously exposed to leptin and/or other factors associated with obesity accumulate excessive amounts of SOCS-3 and CIS which could provide a potential mechanism for leptin resistance.     

Horizontal transmission, vertical inactivation, and stochastic loss of mariner-like transposable elements

Horizontal transmission has been well documented as a major mechanism for the dissemination of mariner-like elements (MLEs) among species. Less well understood are mechanisms that limit vertical transmission of MLEs resulting in the "spotty" or discontinuous distribution observed in closely related species. In this article we present evidence that the genome of the common ancestor of the melanogaster species subgroup of Drosophila contained an MLE related to the mellifera (honey bee) subfamily. Horizontal transmission, approximately 3-10 MYA, is strongly suggested by the observation that the sequence of the MLE in Drosophila erecta is 97% identical in nucleotide sequence with that of an MLE in the cat flea, Ctenocephalides felis. The D. erecta MLE has a spotty distribution among species in the melanogaster subgroup. The element has a high copy number in D. erecta and D. orena, a moderate copy number in D. teissieri and D. yakuba, and was apparently lost ("stochastic loss") in the lineage leading to D. melanogaster, D. simulans, D. mauritiana, and D. sechellia. In D. erecta, most copies are concentrated in the heterochromatin. Two copies from D. erecta, denoted De12 and De19, were cloned and sequenced, and they appear to be nonfunctional ("vertical inactivation"). It therefore appears that the predominant mode of MLE evolution is vertical inactivation and stochastic loss balanced against occasional reinvasion of lineages by horizontal transmission.      

Analysis of the Heterogeneity of the 40,000 Molecular Weight Tuber Glycoprotein of Potatoes by Immunological Methods and by NH(2)-Terminal Sequence Analysis

Among the major soluble tuber proteins of potato (Solanum tuberosum L.) is a group of glycoproteins having apparent molecular weights of approximately 40,000. This group of proteins as purified by ion-exchange and affinity chromatography has been given the trivial name `patatin.' Patatin exists in a number of charge forms which differ between potato cultivars and in some cases can also be resolved into a number of bands by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. However, by immunodiffusion and immunoelectrophoresis, it was found that the isoforms of patatin are immunologically identical both within a cultivar as well as between cultivars. A high degree of homology between the isoforms of patatin is also indicated by NH₂-terminal amino acid sequence analysis.     

Pulmonary metabolic function in the awake lamb: effect of development and hypoxia

The effect of postnatal development and acute alveolar hypoxia on pulmonary metabolic function was studied in conscious newborn lambs. Measurements of the ability of the lungs of these animals to metabolize [3H]benzoyl-L-phenyl-alanyl-L-alanyl-L-proline ([3H]BPAP; a synthetic substrate for angiotensin-converting enzyme, ACE) and to remove 5-hydroxy-[14C]tryptamine (5-[14C]HT) were made by modified indicator-dilution techniques during normoxic and hypoxic (fraction of inspired O2 = 0.10) conditions at 1 day, 1 wk, and 1 mo of age. Six additional sheep (8-23 wk old) were studied acutely as "adult" controls. BPAP metabolism in the 1-day-old group was 48 +/- 3% and increased slowly to 57 +/- 1% (P less than 0.05) at 1 mo of age and to 79 +/- 3% (P less than 0.01) by 23 wk of age. Pulmonary 5-[14C]HT removal was adultlike at birth (69 +/- 2%). Alveolar hypoxia significantly decreased BPAP only in the 1-day-old group (41 +/- 3%; P less than 0.05) and had no significant effect on 5-[14C]HT removal over the range of ages studied. These data demonstrate a selective and gradual postnatal development of pulmonary ACE which could be due to alterations in either the affinity or maximal capacity of pulmonary ACE, or increased endothelial cell surface area secondary to rapid growth of small blood vessels in this period. Alveolar hypoxia does not appear to closely regulate either ACE activity or 5-HT removal in conscious lambs greater than 1 day old when trace amounts of substrate are used.