Morphological convergence and molecular divergence: the taxonomic status of Sceloporus serrifer (squamata,phrynosomatidae) subspecies

Martínez‐Méndez, N., Mejía, O., Rocha‐Gómez, A. & Méndez‐De La Cruz, F. R. (2012) Morphological convergence and molecular divergence: the taxonomic status of Sceloporus serrifer (squamata, phrynosomatidae) subspecies. —Zoologica Scripta, 41, 97–108. The systematics of the subspecies included in Sceloporus serrifer has undergone several taxonomic and nomenclatural rearrangements. This species previously comprised two recognized subspecies, Sceloporus serrifer serrifer and Sceloporus serrifer prezygus, which inhabit contrasting habitats. In this study, we re‐evaluate the taxonomic status of both subspecies using molecular and morphological evidence. Sceloporus serrifer serrifer was recovered as a paraphyletic group, whereas S. s. prezygus was recovered as a polyphyletic group. The molecular results indicate the existence of two independent lineages that diverged at least 1.29 Myr, with the populations currently recognized as S. s. prezygus from the Cuchumatanes Mountains representing a secondary invasion of S. s. serrifer from the lowlands. The lack of meristic differences among the highland populations of different species suggests convergence in similar environments achieved by two different lineages.     

Identification of a platyhelminth neuropeptide receptor

We report the characterisation of the first neuropeptide receptor from the phylum Platyhelminthes, an early-diverging phylum which includes a number of important human and veterinary parasites. The G protein-coupled receptor (GPCR) was identified from the model flatworm Girardia tigrina (Tricladida: Dugesiidae) based on the presence of motifs widely conserved amongst GPCRs. In two different assays utilising heterologous expression in Chinese hamster ovary cells, the Girardia GPCR was most potently activated by neuropeptides from the FMRFamide-like peptide class. The most potent platyhelminth neuropeptide in both assays was GYIRFamide, a FMRFamide-like peptide known to be present in G. tigrina. There was no activation by neuropeptide Fs, another class of flatworm neuropeptides. Also active were FMRFamide-like peptides derived from other phyla but not known to be present in any platyhelminth. Most potent among these were nematode neuropeptides encoded by the Caenorhabditis elegans flp-1 gene which share a PNFLRFamide carboxy terminal motif. The ability of nematode peptides to stimulate a platyhelminth receptor demonstrates a degree of structural conservation between FMRFamide-like peptide receptors from these two distinct, distant phyla which contain parasitic worms.     

A covalent inhibitor targeting an intermediate conformation of the fusogenic subunit of the HIV-1 envelope complex

Peptide inhibitors corresponding to sequences in the six helix bundle structure of the fusogenic portion (gp41) of the HIV envelope glycoprotein have been successfully implemented in preventing HIV entry. These peptides bind to regions in HIV gp41 transiently exposed during the fusion reaction. In an effort to improve upon these entry inhibitors, we have successfully designed and tested peptide analogs composed of chemical spacers and reactive moieties positioned strategically to facilitate covalent attachment. Using a temperature-arrested state prime wash in vitro assay we show evidence for the trapping of a pre-six helix bundle fusion intermediate by a covalent reaction with the specific anti-HIV-1 peptide. This is the first demonstration of the trapping of an intermediate conformation of a viral envelope glycoprotein during the fusion process that occurs in live cells. The permanent specific attachment of the covalent inhibitor is projected to improve the pharmacokinetics of administration in vivo and thereby improve the long-term sustainability of peptide entry inhibitor therapy and help to expand its applicability beyond salvage therapy.     

Effects of hyperoxia periodic training on free radicals production,biological antioxidants potential and lactate dehydrogenase activity in the lungs of rats,Rattus norvigicus

Oxygen therapy has been widely used in lung injury (Li), adult respiraotory syndrome (ARDS) and inflammatory lung diseases as well as in mechanical ventilation in intensive care units. Exposure to hyperoxia is known to induct the production of reactive oxygen species (ROS) by mitochondria. Despite decades of research, the role of hyperoxia training in oxidative stress and ROS formation in the lungs is not known. The purpose of this study was to examine the effects of periodic-hyperoxia training on biological antioxidants (BAP) and lactate dehydrogenase (LDH) activities and free radicals (FR) production. Thirty adult male rats, matched with age and body weigh, were randomly assigned to three groups. The first group served as control (C) and the second (HP) was exposed to hyperoxia for 48. Animals in the third group (HP-T) were trained on hyperoxia for 1.5 h daily for three weeks. Following the exposure period for each group animals were sacrificed and lungs tissues were homogenized for BAP, LDH and FR determinations. LDH activity was determined by Randox protocol (Randox – UK). BAP and FR were determined using dROM method (H&D – Italy). Results showed that mean (±SD) BAP activity increased significantly (p < 0.05) from the baseline control of 7105.88 ± 2021.49 to 8611.20 ± 1245.26 (U/L) after hyperoxia training; then dropped to 6784.00 ± 1879.50 during hyperoxia exposure for 48 h. Whereas mean (±SD) FR production increased significantly (p < 0.05) from the baseline control of 262.50 ± 67.52 to 339.90 ± 64.84 during HP exposure for 48 h, then dropped to 211.13 ± 52.05 (Carr), during HP training. Similarly, LDH activity increased significantly (p < 0.05) from the baseline control of 210.31 ± 70.93 to 339.90 ± 64.84 during HP exposure for 48 h, then dropped to 159.30 ± 20.61(U/L), following HP-periodic training. Furthermore, the correlation (r = 0.67×) of LDH on FR was significant (p < 0.05), implying that reduction in ROS generation induced by HP-periodic training is related to reduced rate of cell apoptosis caused oxidative stress. Based on the results of the present study HP-periodic training is recommended in order to resist oxidative damage in the lungs.     

Phylogenetic placement and population structure of Indo‐Pacific bottlenose dolphins (Tursiops aduncus) off Zanzibar,Tanzania, based on mtDNA sequences

Phylogenetic placement of bottlenose dolphins from Zanzibar, East Africa and putative population differentiation between animals found off southern and northern Zanzibar were examined using variation in mtDNA control region sequences. Samples (n= 45) from animals bycaught in fishing gear and skin biopsies collected during boat surveys were compared to published sequences (n= 173) of Indo‐Pacific bottlenose dolphin, Tursiops aduncus, from southeast Australian waters, Chinese/Indonesian waters, and South African waters (which recently was proposed as a new species) and to published sequences of common bottlenose dolphin, Tursiops truncatus. Bayesian and maximum parsimony analyses indicated a close relationship between Zanzibar and South African haplotypes, which are differentiated from both Chinese/Indonesian and Australian T. aduncus haplotypes. Our results suggest that the dolphins found off Zanzibar should be classified as T. aduncus alongside the South African animals. Further, analyses of genetic differentiation showed significant separation between the T. aduncus found off northern and southern Zanzibar despite the relatively short distance (approximately 80 km) between these areas. Much less differentiation was found between southern Zanzibar and South Africa, suggesting a more recent common evolutionary history for these populations than for the northern and southern Zanzibar populations.     

Evolutionary History of the Live-Bearing Endemic Allotoca diazi Species Complex (Actinopterygii,Goodeinae): Evidence of Founder Effect Events in the Mexican Pre-Hispanic Period

The evolutionary history of Mexican ichthyofauna has been strongly linked to natural events, and the impact of pre-Hispanic cultures is little known. The live-bearing fish species Allotoca diazi, Allotoca meeki and Allotoca catarinae occur in areas of biological, cultural and economic importance in central Mexico: Pátzcuaro basin, Zirahuén basin, and the Cupatitzio River, respectively. The species are closely related genetically and morphologically, and hypotheses have attempted to explain their systematics and biogeography. Mitochondrial DNA and microsatellite markers were used to investigate the evolutionary history of the complex. The species complex shows minimal genetic differentiation. The separation of A. diazi and A. meeki was dated to 400–7000 years ago, explained by geological and climate events. A bottleneck and reduction of genetic diversity in Allotoca diazi was detected, attributed to recent climate fluctuations and anthropogenic activity. The isolation of A. catarinae occurred ~1900 years ago. No geological events are documented in the area during this period, but the date is contemporary with P’urhépecha culture settlements. This founder effect represents the first evidence of fish species translocation by a pre-Hispanic culture of Mexico. The response of the complex to climate fluctuation, geological changes and human activity in the past and the future according to the ecological niches predictions indicates areas of vulnerability and important information for conservation. The new genetic information showed that the Allotoca diazi complex consist of two genetic groups with an incomplete lineage sorting pattern: Pátzcuaro and Zirahuén lakes, and an introduced population in the Cupatitzio River.     

Optimizing Mycobacterial Culture in Smear-Negative,Human Immunodeficiency Virus-Infected Tuberculosis Cases

Introduction

Tuberculosis (TB) is a significant public health problem and the diagnosis in human immunodeficiency virus (HIV)—infected individuals is challenging. The use of mycobacterial culture remains an important complementary tool and optimizing it has important benefits. We sought to determine the effect of an increase in the number of specimens evaluated, addition of nutritional supplementation to the culture medium, sputum appearance and volume on diagnostic yield and time to detection of pulmonary TB among smear-negative, HIV-infected adults.

Methods

In this prospective study conducted at the Tshwane District Hospital and Academic TB Laboratory, Pretoria, South Africa we collected three sputum specimens an hour apart from presumptive TB cases at an antiretroviral treatment site. We analysed specimens from 236 patients. Specimen appearance and volume were recorded. All specimens were processed for culture using both standard and supplemented media.

Results

A single specimen identified 79% of PTB cases using standard media; the second and third specimens added 12.5% and 8.3% respectively. Media supplementation, sputum appearance and specimen volume had no effect on culture yield or contamination rates. The mean time to detection was reduced from 19.8 days in standard cultures to 11.8 days in nutrient supplemented cultures (p = 0.002). For every 1 ml increase in sputum volume, time to detection was decreased by a factor of 0.797 (p = 0.011).

Conclusion

Use of an inexpensive culture supplement substantially reduced time to detection and could contribute to reducing treatment delay among HIV-infected cases.     

Independent Demographic Responses to Climate Change among Temperate and Tropical Milksnakes (Colubridae: Genus Lampropeltis)

The effects of Late Quaternary climate change have been examined for many temperate New World taxa, but the impact of Pleistocene glacial cycles on Neotropical taxa is less well understood, specifically with respect to changes in population demography. Here, we examine historical demographic trends for six species of milksnake with representatives in both the temperate and tropical Americas to determine if species share responses to climate change as a taxon or by area (i.e., temperate versus tropical environments). Using a multilocus dataset, we test for the demographic signature of population expansion and decline using non-genealogical summary statistics, as well as coalescent-based methods. In addition, we determine whether range sizes are correlated with effective population sizes for milksnakes. Results indicate that there are no identifiable trends with respect to demographic response based on location, and that species responded to changing climates independently, with tropical taxa showing greater instability. There is also no correlation between range size and effective population size, with the largest population size belonging to the species with the smallest geographic distribution. Our study highlights the importance of not generalizing the demographic histories of taxa by region and further illustrates that the New World tropics may not have been a stable refuge during the Pleistocene.     

Large-Scale Patterns of Turnover and Basal Area Change in Andean Forests

General patterns of forest dynamics and productivity in the Andes Mountains are poorly characterized. Here we present the first large-scale study of Andean forest dynamics using a set of 63 permanent forest plots assembled over the past two decades. In the North-Central Andes tree turnover (mortality and recruitment) and tree growth declined with increasing elevation and decreasing temperature. In addition, basal area increased in Lower Montane Moist Forests but did not change in Higher Montane Humid Forests. However, at higher elevations the lack of net basal area change and excess of mortality over recruitment suggests negative environmental impacts. In North-Western Argentina, forest dynamics appear to be influenced by land use history in addition to environmental variation. Taken together, our results indicate that combinations of abiotic and biotic factors that vary across elevation gradients are important determinants of tree turnover and productivity in the Andes. More extensive and longer-term monitoring and analyses of forest dynamics in permanent plots will be necessary to understand how demographic processes and woody biomass are responding to changing environmental conditions along elevation gradients through this century.