Human immunodeficiency virus type 1 recombinant B/G subtypes circulating in Coimbra, Portugal.

An increasing prevalence of HIV-1 non-B variants is being noticed in several European regions, particularly in countries such as Portugal, which have closer contacts with African endemic areas, where multiple HIV subtypes cocirculate. HIV-1 subtyping by phylogenetic analyses of reverse transcriptase, protease and env (C2-V3) genomic regions was carried out in plasma collected from 18 HIV-1-infected subjects living in Coimbra, Portugal, and suspected to be infected with non-B variants. Three (16.7%) subjects carried recombinant B/G viruses (BV3/BRT/Gpro; GV3/URT/Bpro; AV3/GRT/Bpro), whereas all the remaining individuals were infected with HIV-1 subtype B. This is the first report of recombinant B/G subtypes in Portugal

Community Impacts of Prosopis Juliflora Invasion: Biogeographic and Congeneric Comparisons

We coordinated biogeographical comparisons of the impacts of an exotic invasive tree in its native and non-native ranges with a congeneric comparison in the non-native range. Prosopis juliflora is taxonomically complicated and with P. pallida forms the P. juliflora complex. Thus we sampled P. juliflora in its native Venezuela, and also located two field sites in Peru, the native range of Prosopis pallida. Canopies of Prosopis juliflora, a native of the New World but an invader in many other regions, had facilitative effects on the diversity of other species in its native Venezuela, and P. pallida had both negative and positive effects depending on the year, (overall neutral effects) in its native Peru. However, in India and Hawaii, USA, where P. juliflora is an aggressive invader, canopy effects were consistently and strongly negative on species richness. Prosopis cineraria, a native to India, had much weaker effects on species richness in India than P. juliflora. We carried out multiple congeneric comparisons between P. juliflora and P. cineraria, and found that soil from the rhizosphere of P. juliflora had higher extractable phosphorus, soluble salts and total phenolics than P. cineraria rhizosphere soils. Experimentally applied P. juliflora litter caused far greater mortality of native Indian species than litter from P. cineraria. Prosopis juliflora leaf leachate had neutral to negative effects on root growth of three common crop species of north-west India whereas P. cineraria leaf leachate had positive effects. Prosopis juliflora leaf leachate also had higher concentrations of total phenolics and L-tryptophan than P. cineraria, suggesting a potential allelopathic mechanism for the congeneric differences. Our results also suggest the possibility of regional evolutionary trajectories among competitors and that recent mixing of species from different trajectories has the potential to disrupt evolved interactions among native species

Community Impacts of <em>Prosopis juliflora</em> Invasion: Biogeographic and Congeneric Comparisons

<div><p>We coordinated biogeographical comparisons of the impacts of an exotic invasive tree in its native and non-native ranges with a congeneric comparison in the non-native range. <em>Prosopis juliflora</em> is taxonomically complicated and with <em>P. pallida</em> forms the <em>P. juliflora</em> complex. Thus we sampled <em>P. juliflora</em> in its native Venezuela, and also located two field sites in Peru, the native range of <em>Prosopis pallida.</em> Canopies of <em>Prosopis juliflora</em>, a native of the New World but an invader in many other regions, had facilitative effects on the diversity of other species in its native Venezuela, and <em>P. pallida</em> had both negative and positive effects depending on the year, (overall neutral effects) in its native Peru. However, in India and Hawaii, USA, where <em>P. juliflora</em> is an aggressive invader, canopy effects were consistently and strongly negative on species richness. <em>Prosopis cineraria</em>, a native to India, had much weaker effects on species richness in India than <em>P. juliflora</em>. We carried out multiple congeneric comparisons between <em>P. juliflora</em> and <em>P. cineraria</em>, and found that soil from the rhizosphere of <em>P. juliflora</em> had higher extractable phosphorus, soluble salts and total phenolics than <em>P. cineraria</em> rhizosphere soils. Experimentally applied <em>P. juliflora</em> litter caused far greater mortality of native Indian species than litter from <em>P. cineraria</em>. <em>Prosopis juliflora</em> leaf leachate had neutral to negative effects on root growth of three common crop species of north-west India whereas <em>P. cineraria</em> leaf leachate had positive effects. <em>Prosopis juliflora</em> leaf leachate also had higher concentrations of total phenolics and L-tryptophan than <em>P. cineraria,</em> suggesting a potential allelopathic mechanism for the congeneric differences. Our results also suggest the possibility of regional evolutionary trajectories among competitors and that recent mixing of species from different trajectories has the potential to disrupt evolved interactions among native species.</p> </div

Total phenolic content (mean + SE) of soil amended with <i>Prosopis cineraria</i> (gray bar) and <i>P. juliflora</i> (black bar) leaf leachates and unamended soil (control, white bar). (A)

<p>Different letters above bars indicate significant differences (ANOVA, post-ANOVA Tukey’s test; p<0.05). <b>(B)</b> Total phenolic content (mean ± SE) of soil treated with no litter (white circles), <i>P. cineraria</i> (gray circles) or <i>P. juliflora</i> leaf litter (black circles) at rate of 12 mg/g soil, and incubated at 30–34°C under 12 h/12 h light/dark cycle for 0, 1, 2, 3, 4, 6, 8, 10 and14 days.</p

Root length (proportion of control, %) of <i>Brassica campestris</i> (upper panel), <i>B. juncea</i> (middle panel) and <i>Sorghum bicolor</i> (lower panel) seedlings grown in soil treated with different amounts (60, 150 and 300 µL/g soil) of <i>Prosopis cineraria</i> (gray bars) or <i>Prosopis juliflora</i> (black bars) leaf leachate.

<p>Soil treated with distilled water served as untreated control (white bars). Error bars represent +1SE of mean. F and P values are shown for two way ANOVAs.</p

Plant species richness (mean + SE) beneath canopies of <i>P. juliflora,</i> its native congener <i>P. cineraria</i>, and from open areas.

<p>Differences in plant species richness beneath <i>P. cineraria</i> and <i>P. juliflora</i> canopies and open areas were tested using one way-ANOVA and post-hoc Tukey’s test (p<0.05).</p

Chemical properties – pH (A), electrical conductivity (B), organic carbon (C), PO₄^3–Phosphorus (D), total organic nitrogen (E) and total phenolic content (F) of soil from the rhizosphere of <i>Prosopis juliflora</i>, <i>Prosopis cineraria</i> and soil from adjacent open area in Punjab, India.

<p>Error bars represent +1SE of mean. Different letters above bars indicate significant differences (one way ANOVA, post-ANOVA Tukey’s test; p<0.05).</p

<i>Prosopis juliflora</i> in its native range of Venezuela (A); the invaded range of Haryana, India (B), along the National Highway to Rajasthan (C), at the boundaries of an agricultural field in India (D), and in Hawaii, USA (E); <i>Prosopis cineraria</i> in its native range, Rajasthan, India (F).

<p>Photo credits: Pascual J. Soriano (A); Inderjit (B, C, D and F) and Timothy J. Gallaher (E).</p

Mortality (mean + SE) of different species - <i>Acacia nilotica, Brassica campestris, Brassica juncea, Chloris dolichostachya, Dalbergia sissoo</i> and <i>Prosopis cineraria</i> - when grown in soil amended with leaf litter of <i>Prosopis juliflora</i> (black box), <i>P. cineraria</i> (gray box) or without litter (white box).

<p>Different letters above bars indicate significant differences (one way ANOVA, post-ANOVA Tukey’s test; p<0.05).</p