Temporal Changes and Altitudinal Distribution of Aerobic Anoxygenic Phototrophs in Mountain Lakes

Aerobic anoxygenic phototrophs (AAPs) are bacteriochlorophyll a-containing microorganisms that use organic substrates for growth but can supplement their energy requirements with light. They have been reported from various marine and limnic environments; however, their ecology remains largely unknown. Here infrared epifluorescence microscopy was used to monitor temporal changes in AAPs in the alpine lake Gossenköllesee, located in the Tyrolean Alps, Austria. AAP abundance was low (10³ cells ml⁻¹) until mid-July and reached a maximum of ∼1.3 × 10⁵ cells ml⁻¹ (29% of all prokaryotes) in mid-September. We compared the studied lake with other mountain lakes located across an altitudinal gradient (913 to 2,799 m above sea level). The concentration of dissolved organic carbon and water transparency seem to be the main factors influencing AAP abundance during the seasonal cycle as well as across the altitudinal gradient. While the AAP populations inhabiting the alpine lakes were composed of intensely pigmented large rods (5 to 12 μm), the lakes below the tree line were inhabited by a variety of smaller morphotypes. Analysis of pufM diversity revealed that AAPs in Gossenköllesee were almost exclusively Sphingomonadales species, which indicates that AAP communities inhabiting alpine lakes are relatively homogeneous compared to those in low-altitude lakes.     

HIV Drug Resistance Surveillance in Honduras after a Decade of Widespread Antiretroviral Therapy

Introduction

We assessed HIV drug resistance (DR) in individuals failing ART (acquired DR, ADR) and in ART-naïve individuals (pre-ART DR, PDR) in Honduras, after 10 years of widespread availability of ART.

Methods

365 HIV-infected, ART-naïve, and 381 ART-experienced Honduran individuals were enrolled in 5 reference centres in Tegucigalpa, San Pedro Sula, La Ceiba, and Choluteca between April 2013 and April 2015. Plasma HIV protease-RT sequences were obtained. HIVDR was assessed using the WHO HIVDR mutation list and the Stanford algorithm. Recently infected (RI) individuals were identified using a multi-assay algorithm.

Results

PDR to any ARV drug was 11.5% (95% CI 8.4–15.2%). NNRTI PDR prevalence (8.2%) was higher than NRTI (2.2%) and PI (1.9%, p<0.0001). No significant trends in time were observed when comparing 2013 and 2014, when using a moving average approach along the study period or when comparing individuals with >500 vs. <350 CD4+ T cells/μL. PDR in recently infected individuals was 13.6%, showing no significant difference with PDR in individuals with longstanding infection (10.7%). The most prevalent PDR mutations were M46IL (1.4%), T215 revertants (0.5%), and K103NS (5.5%). The overall ADR prevalence in individuals with <48 months on ART was 87.8% and for the ≥48 months on ART group 81.3%. ADR to three drug families increased in individuals with longer time on ART (p = 0.0343). M184V and K103N were the most frequent ADR mutations. PDR mutation frequency correlated with ADR mutation frequency for PI and NNRTI (p<0.01), but not for NRTI. Clusters of viruses were observed suggesting transmission of HIVDR both from ART-experienced to ART-naïve individuals and between ART-naïve individuals.

Conclusions

The global PDR prevalence in Honduras remains at the intermediate level, after 10 years of widespread availability of ART. Evidence of ADR influencing the presence of PDR was observed by phylogenetic analyses and ADR/PDR mutation frequency correlations.     

Chimeric epitopes delivered by polymeric synthetic linear peptides induce protective immunity to malaria

Polymeric linear peptide chimeras (LPCs) that incorporate Plasmodium vivax promiscuous T cell epitopes and the P. falciparum circumsporozoite protein B cell epitope have been shown to induce a high level of immunogenicity and overcome genetic restriction when tested as vaccine immunogens in BALB/c mice. The present study evaluates the biological relevance of several LPCs using a well characterized rodent malaria model. Polymeric peptide constructs based on P. berghei and P. yoelii sequences, and orthologous to the human malaria sequences included in the original LPCs, were designed and tested for immunogenicity in mice of different H-2 haplotypes. We demonstrate that robust immune responses are induced and that peptides containing the orthologous rodent Plasmodium sequences exhibited similar immunogenic capabilities. Unique to this report, we show that LPCs can also prime MHC class I-restricted cytotoxic T lymphocytes (CTLs) and, most relevantly, that a peptide construct prototype incorporating single B, T and CTL epitopes induced protection against an experimental challenge with P. berghei or P. yoelii sporozoites. Collectively, these results suggest that polymeric polypeptide chimeras can be used as a platform to deliver subunit vaccines.     

Population Responses to Environmental Change in a Tropical Ant: The Interaction of Spatial and Temporal Dynamics

Spatial structure can have a profound, but often underappreciated, effect on the temporal dynamics of ecosystems. Here we report on a counterintuitive increase in the population of a tree-nesting ant, Azteca sericeasur, in response to a drastic reduction in the number of potential nesting sites. This surprising result is comprehensible when viewed in the context of the self-organized spatial dynamics of the ants and their effect on the ants’ dispersal-limited natural enemies. Approximately 30% of the trees in the study site, a coffee agroecosystem in southern Mexico, were pruned or felled over a two-year period, and yet the abundance of the ant nests more than doubled over the seven-year study. Throughout the transition, the spatial distribution of the ants maintained a power-law distribution – a signal of spatial self organization – but the local clustering of the nests was reduced post-pruning. A cellular automata model incorporating the changed spatial structure of the ants and the resulting partial escape from antagonists reproduced the observed increase in abundance, highlighting how self-organized spatial dynamics can profoundly influence the responses of ecosystems to perturbations.     

Aerobiological investigations inside repositories of the National Archive of the Republic of Cuba

The objectives of this study were to evaluate the microbial prevalence inside six repositories of the National Archive of the Republic of Cuba in 2?months of the year and to examine some of the physiological features of fungi isolated in order to evaluate their potential for biodeterioration. The microbiological sampling was conducted in February and September using a slit impactor as air sampler. Appropriate selective culture media were used to isolate fungi and bacteria. Temperature and relative humidity were measured during the samplings. The cellulolytic activity and the production of acids and pigments of the fungi isolated were qualitatively determined. Total viable microbiota and bacteria concentrations were greater in February while the fungal concentration was higher in September. Aspergillus, Cladosporium, Penicillium, Curvularia and Alternaria were the predominant fungal genera in February while Cladosporium prevailed in September, although Fusarium, Mucor and Neurospora genera were also isolated in this month. The fungi isolated were capable of degrading cellulose and excreting pigments and acids. The Gram-positive bacteria group prevailed in the air and Corynebacterium, Streptomyces, Bacillus, Streptococcus, Staphylococcus, Enterobacter and Serratia were some of the genera identified.     

Coenzyme Q production by metabolic engineered Escherichia coli strains in defined medium

Bioprocess and Biosystems Engineering - Coenzyme Q (CoQ) plays an important role as an electron transporter in the respiratory chain. It is formed from a benzoquinone ring and an isoprenoid chain...     

Phase Relations between Host and Grafted SCN Depend on Graft Location in Rats

Fetal SCN grafts into intact rats were used as a model to study coupling among circadian oscillators. The phase relation in metabolic activity was analyzed between host SCN and fetal SCN grafted into the third (n = 24) or lateral (n = 18) ventricles. Host and third ventricle SCN grafts showed metabolic activity rhythms with peak values at CT 6, as extrapolated from drinking rhythmicity. In lateral ventricle grafted animals only the host SCN showed rhythmicity, although peak values oc curred as indicated by the drinking rhythms at CT 9. The present data suggest asymmetrical communication between host and grafted SCN depending on graft location, which may be related to different types of signal transmission.     

A Keystone Ant Species Provides Robust Biological Control of the Coffee Berry Borer Under Varying Pest Densities

Species’ functional traits are an important part of the ecological complexity that determines the provisioning of ecosystem services. In biological pest control, predator response to pest density variation is a dynamic trait that impacts the provision of this service in agroecosystems. When pest populations fluctuate, farmers relying on biocontrol services need to know how natural enemies respond to these changes. Here we test the effect of variation in coffee berry borer (CBB) density on the biocontrol efficiency of a keystone ant species (Azteca sericeasur) in a coffee agroecosystem. We performed exclosure experiments to measure the infestation rate of CBB released on coffee branches in the presence and absence of ants at four different CBB density levels. We measured infestation rate as the number of CBB bored into fruits after 24 hours, quantified biocontrol efficiency (BCE) as the proportion of infesting CBB removed by ants, and estimated functional response from ant attack rates, measured as the difference in CBB infestation between branches. Infestation rates of CBB on branches with ants were significantly lower (71%-82%) than on those without ants across all density levels. Additionally, biocontrol efficiency was generally high and did not significantly vary across pest density treatments. Furthermore, ant attack rates increased linearly with increasing CBB density, suggesting a Type I functional response. These results demonstrate that ants can provide robust biological control of CBB, despite variation in pest density, and that the response of predators to pest density variation is an important factor in the provision of biocontrol services. Considering how natural enemies respond to changes in pest densities will allow for more accurate biocontrol predictions and better-informed management of this ecosystem service in agroecosystems.     

A Single Early Introduction of HIV-1 Subtype B into Central America Accounts for Most Current Cases

Human immunodeficiency virus type 1 (HIV-1) variants show considerable geographical separation across the world, but there is limited information from Central America. We provide the first detailed investigation of the genetic diversity and molecular epidemiology of HIV-1 in six Central American countries. Phylogenetic analysis was performed on 625 HIV-1 pol gene sequences collected between 2002 and 2010 in Honduras, El Salvador, Nicaragua, Costa Rica, Panama, and Belize. Published sequences from neighboring countries (n = 57) and the rest of the world (n = 740) were included as controls. Maximum likelihood methods were used to explore phylogenetic relationships. Bayesian coalescence-based methods were used to time HIV-1 introductions. Nearly all (98.9%) Central American sequences were of subtype B. Phylogenetic analysis revealed that 437 (70%) sequences clustered within five significantly supported monophyletic clades formed essentially by Central American sequences. One clade contained 386 (62%) sequences from all six countries; the other four clades were smaller and more country specific, suggesting discrete subepidemics. The existence of one large well-supported Central American clade provides evidence that a single introduction of HIV-1 subtype B in Central America accounts for most current cases. An introduction during the early phase of the HIV-1 pandemic may explain its epidemiological success. Moreover, the smaller clades suggest a subsequent regional spread related to specific transmission networks within each country.     

Endogenous clock gene expression in the suprachiasmatic nuclei of previsual newborn rabbits is entrained by nursing

The rabbit is particularly suitable for investigating the development of mammalian circadian function. Blind at birth, the pups are only visited by the mother to be nursed once every 24 h for about 3 min and so can be studied largely without maternal interference. They anticipate the mother's visit with increased behavioral arousal and with a rise in body temperature, both of which represent endogenous circadian rhythms. We now report that in newborn pups the suprachiasmatic nuclei of the hypothalamus (SCN; the main circadian pacemaker in mammals) show endogenous 24‐h rhythmicity in the expression of the clock genes Per1, Per2, and Bmal1. Pups nursed from postnatal days 1 to 7 and fasted to day 9 showed the same rhythms of clock gene expression as normally nursed controls. We also report that these rhythms are entrained by nursing. Pups killed on postnatal days 3–4 showed the same rhythms in gene expression as pups in the previous experiment, whereas littermates subsequently nursed from postnatal days 4 to 7 with nursing delayed 6 h showed a corresponding shift in the diurnal pattern of clock gene expression. Consistent with this, two groups of pups implanted with telemetric thermal sensors and nursed 6 h apart had daily patterns in body temperature synchronized with the two different nursing times. We conclude that the expression of clock genes associated with the newborn rabbit's circadian system is entrained by nonphotic cues accompanying nursing, the exact nature of which now needs to be clarified. © 2008 Wiley Periodicals, Inc. Develop Neurobiol, 2009