Release of Membrane-Bound Trails by Trypanosoma cruzi Amastigotes onto Modified Surfaces and Mammalian Cells

ABSTRACT. Upon incubation at 37° C onto glass coverslips coated with Concanavalin A, poly-L-lysine, or a monoclonal antibody (1D9) directed to the parasite major surface glycoprotein Ssp-4, extracellular Trypanosoma cruzi amastigotes release trails of material barely visible by light microscopy. This release is not associated with parasite movements. Immunolabeling studies confirmed that the material is derived from the parasite's membrane since thin section through samples labeled with 1D9 revealed that the trails are membrane-bound structures. Scanning electron microscopy showed that the ∼0.1-μm thick trails of material emerging from the amastigotes can be uniform or beaded, indicating a tendency to vesiculation. The trails are preferentially released from the flagellar pocket region and/or at the opposite posterior end of the parasite body, and seem to be devoid of microtubules. The release is time and temperature-dependent and fixed parasites do not form trails. All attempts to inhibit trail release using drugs (antimycin A, sodium azide, cytochalasin D, nocodazole, genistein, staurosporine, EGTA) failed. The observation of trails associated with intracellular parasites and amastigotes invading Vero cells suggests that this is probably a physiological process.     

A new species of Exostyles (Leguminosae, Papilionoideae, Swartzieae s.l.), from Paraná State, Brazil

A new species Exostyles godoyensis Soares-Silva & Mansano (Leguminosae, Papilionoideae, Swartzieae), endemic to Paraná state in southern Brazil, is described and illustrated. The new species is distinct from all the other species of Exostyles in having a leaf with up to five leaflets, while the other species have at least seven leaflets per leaf. The new species is distinct from Exostyles amazonica Yakovlev in its longer stamen filaments and ovary stipe and from E. glabra Vogel and E. venusta Schott by its shorter anthers. In addition to these morphological characters E. godoyensis has a disjunct geographical distribution.  © 2004 The Linnean Society of London, Botanical Journal of the Linnean Society , 2004, 146 , 103–106.     

Summer distribution of Red-legged Partridges Alectoris rufa in relation to water availability on Mediterranean farmland

The suggestion that the summer distribution of Red-legged Partridges Alectoris rufa in the Mediterranean region is determined by the availability of surface water was examined on the agricultural farm, Alto Alentejo, southern Portugal. Partridge coveys were surveyed between 15 July and 15 August in 1993 and 1994. Using a vector-based Geographic Information System, we assessed, for each covey location and for the locations of a double number of random points, the distance to the nearest water point, distance to field boundaries, distance to water lines and land use classes. Univariate comparisons were made between the two groups of locations, and three multivariate logistic models were fitted through forward stepwise selection to the 1993, 1994 and pooled data sets to estimate the probability of sighting partridge coveys in the study area. Distance to water was significantly lower for partridge locations than for random points in both years and was the only variable selected for all logistic models. Apart from water availability, Red-legged Partridge locations were also affected by land use and distance to field boundaries.     

Ten polymorphic tetranucleotide microsatellite markers isolated from the Anolis roquet series of Caribbean lizards

The Anolis roquet series of Caribbean lizards provides natural replicates with which to examine the role of historical contingency and ecological determinism in shaping evolutionary patterns. Here, we describe 10 polymorphic tetranucleotide microsatellites to facilitate studies on population differentiation and gene flow. All loci successfully amplified in several species from this series. Genotyping 96 individuals from two A. roquet populations demonstrated the markers’ suitability as population genetic markers: genetic diversity was high (9–22 alleles per locus); there were no instances of linkage disequilibrium; and, with one exception, all genotypic frequencies conformed to Hardy–Weinberg equilibrium expectations.     

The effect of ponderal index at birth on the relationships between common LEP and LEPR polymorphisms and adiposity in adolescents

This study examined the effect of ponderal index (PI) at birth on the relationships between eight common polymorphisms of the leptin (LEP) and leptin receptor (LEPR) genes and adiposity in adolescents. A total of 823 European adolescents (45.4% girls) aged 14.8 ± 1.4 years were genotyped for the LEP (rs2167270, rs12706832, rs10244329, rs2071045, and rs3828942) and LEPR (rs1137100, rs1137101, and rs8179183) polymorphisms. The PI was calculated from parental reports of birth weight and length. Fat mass index (FMI) was calculated. Analyses were adjusted for relevant confounders. An "adiposity-risk-allele score" based on genotypes at the three single-nucleotide polymorphisms (SNPs) associated with adolescents' FMI in adolescents within the lower tertile of PI was calculated. The LEP rs10244329 and rs3828942 polymorphisms were associated with higher FMI only in adolescents within the lower PI tertile (+0.55 kg/m(2) per minor T allele, P = 0.040, and +0.58 kg/m(2) per major G allele, P = 0.028, respectively). The LEPR rs8179183 polymorphism was significantly associated with higher FMI in adolescents within the lower PI tertile (+0.87 kg/m(2) per minor C allele, P = 0.006). After correction for multiple comparisons, only the association between the LEPR rs8179183 and FMI persisted. However, each additional risk allele conferred 0.53 kg/m(2) greater FMI in adolescents within the lower tertile of PI (P = 0.008). In conclusion, our results suggest that those adolescents born with lower PI could be more vulnerable to the influence of the LEP rs10244329 and rs3828942 polymorphisms and LEPR rs8179183 polymorphism on total adiposity content. Due to the relatively small sample size, these findings should be replicated in further larger population samples.     

In Vitro Responses of Brassica Juncea and Vigna radiata to the Antibiotic Kanamycin

Growth responses of Brassica juncea and Vigna radiata were studiedin vitro in the presence of the antibiotic kanamycin. The dataindicate that the kanamycin concentration for the inhibitionof growth varied considerably in both the species as well asin different explants of the same species. Brassica juncea, mustard, kanamycin, Vigna radiata, mung bean     

The roles of allopatric divergence and natural selection in quantitative trait variation across a secondary contact zone in the lizard Anolis roquet

Populations of the Caribbean lizard, Anolis roquet, are thought to have experienced long periods of allopatry before recent secondary contact. To elucidate the effects of past allopatry on population divergence in A. roquet, we surveyed parallel transects across a secondary contact zone in northeastern Martinique. We used diagnostic molecular mitochondrial DNA markers to test fine‐scale association of mitochondrial DNA lineage and geological region, multivariate statistical techniques to explore quantitative trait pattern, and cline fitting techniques to model trait variation across the zone of secondary contact. We found that lineages were strongly associated with geological regions along both transects, but quantitative trait patterns were remarkably different. Patterns of morphological and mitochondrial DNA variation were consistent with a strong barrier to gene flow on the coast, whereas there were no indications of barriers to gene flow in the transitional forest. Hence, the coastal populations behaved as would be predicted by an allopatric model of divergence in this complex, while those in the transitional forest did not, despite the close proximity of the transects and their shared geological history. Patterns of geographical variation in this species complex, together with environmental data, suggest that on balance, selection regimes on either side of the secondary contact zone in the transitional forest may be more convergent, while those either side of the secondary contact zone on the coast are more divergent. Hence, the evolutionary consequences of allopatry may be strongly influenced by local natural selection regimes.     

Morphotypes,varieties, or subspecies?: genetic diversity and differentiation of four Saintpaulia (Gesneriaceae) morphotypes from the East Usambara Mountains,Tanzania

Saintpaulia (H. Wendl.) is a forest-dependent, endangered plant genus endemic to Tanzania and Kenya. The taxonomy of Saintpaulia from the Usambara Mountains and adjacent lowlands in north-eastern Tanzania is problematic because of the morphological similarity of the species and the presence of considerable intraspecific variation. Conventional molecular phylogenetic methods have failed to reveal the genetic structure of this Saintpaulia complex. In this study, we assessed the genetic composition of 12 Saintpaulia populations, representing four different morphotypes, from the East Usambara Mountains using inter-simple sequence repeat (ISSR) markers. Relatively high genetic diversities were observed within populations (mean h  = 0.320), indicating their adaptive potential. Little genetic differentiation amongst populations (mean F _st  = 0.063) and the genetic divergence of the rosulate and trailing morphotypes support the hypothesis of ongoing divergent evolution within the East Usambara metapopulation(s) of Saintpaulia .  © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society , 2008, 157 , 347–355.