Multiple introductions of the Old World begomovirus Tomato yellow leaf curl virus into the New World

A phylogenetic analysis of three genomic regions revealed that Tomato yellow leaf curl virus (TYLCV) from western North America is distinct from TYLCV isolated in eastern North America and the Caribbean. This analysis supports a second introduction of this Old World begomovirus into the New World, most likely from Asia.     

Computational survey of peptides derived from disulphide-bonded protein loops that may serve as mediators of protein-protein interactions

Background

Bioactive cyclic peptides derived from natural sources are well studied, particularly those derived from non-ribosomal synthetases in fungi or bacteria. Ribosomally synthesised bioactive disulphide-bonded loops represent a large, naturally enriched library of potential bioactive compounds, worthy of systematic investigation.

Results

We examined the distribution of short cyclic loops on the surface of a large number of proteins, especially membrane or extracellular proteins. Available three-dimensional structures highlighted a number of disulphide-bonded loops responsible for the majority of the likely binding interactions in a variety of protein complexes, due to their location at protein-protein interfaces. We find that disulphide-bonded loops at protein-protein interfaces may, but do not necessarily, show biological activity independent of their parent protein. Examining the conservation of short disulphide bonded loops in proteins, we find a small but significant increase in conservation inside these loops compared to surrounding residues. We identify a subset of these loops that exhibit a high relative conservation, particularly among peptide hormones.

Conclusions

We conclude that short disulphide-bonded loops are found in a wide variety of biological interactions. They may retain biological activity outside their parent proteins. Such structurally independent peptides may be useful as biologically active templates for the development of novel modulators of protein-protein interactions.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2105-15-305) contains supplementary material, which is available to authorized users.     

Might Cortical Hyper-Responsiveness in Aging Contribute to Alzheimer’s Disease?

Our goal is to understand the neural basis of functional impairment in aging and Alzheimer’s disease (AD) to be able to characterize clinically significant decline and assess therapeutic efficacy. We used frequency-tagged ERPs to word and motion stimuli to study the effects of stimulus conditions and selective attention. ERPs to word or motion increase when a task-irrelevant 2^nd stimulus is added, but decrease when the task is moved to that 2^nd stimulus. Spectral analyses show task effects on response power without 2^nd stimulus effects. However, phase coherence shows both 2^nd stimulus and task effects. Thus, power and coherence are dissociably modulated by stimulus and task effects. Task-dependent phase coherence successively declines in aging and AD. In contrast, task-dependent spectral power increases in aging, only to decrease in AD. We hypothesize that age-related declines in signal coherence, associated with increased power generation, stresses neurons and contributes to the loss of response power and the development of functional impairment in AD.     

A Temporal Dimension to the Influence of Pollen Rewards on Bee Behaviour and Fecundity in Aloe tenuior

The net effect of pollen production on fecundity in plants can range from negative – when self-pollen interferes with fecundity due to incompatibility mechanisms, to positive – when pollen availability is associated with increased pollinator visitation and fecundity due to its utilization as a reward. We investigated the responses of bees to pollen and nectar rewards, and the effects of these rewards on pollen deposition and fecundity in the hermaphroditic succulent shrub Aloe tenuior. Self-pollinated plants failed to set fruit, but their ovules were regularly penetrated by self-pollen tubes, which uniformly failed to develop into seeds as expected from ovarian self-incompatibility (or strong early inbreeding depression). Bees consistently foraged for pollen during the morning and early afternoon, but switched to nectar in the late afternoon. As a consequence of this differential foraging, we were able to test the relative contribution to fecundity of pollen- versus nectar-collecting flower visitors. We exposed emasculated and intact flowers in either the morning or late afternoon to foraging bees and showed that emasculation reduced pollen deposition by insects in the morning, but had little effect in the afternoon. Despite the potential for self-pollination to result in ovule discounting due to late-acting self-sterility, fecundity was severely reduced in artificially emasculated plants. Although there were temporal fluctuations in reward preference, most bee visits were for pollen rewards. Therefore the benefit of providing pollen that is accessible to bee foragers outweighs any potential costs to fitness in terms of gender interference in this species.     

Exclusion of agricultural lands in spatial conservation prioritization strategies: consequences for biodiversity and ecosystem service representation

Agroecosystems have traditionally been considered incompatible with biological conservation goals, and often been excluded from spatial conservation prioritization strategies. The consequences for the representativeness of identified priority areas have been little explored. Here, we evaluate these for biodiversity and carbon storage representation when agricultural land areas are excluded from a spatial prioritization strategy for South America. Comparing different prioritization approaches, we also assess how the spatial overlap of priority areas changes. The exclusion of agricultural lands was detrimental to biodiversity representation, indicating that priority areas for agricultural production overlap with areas of relatively high occurrence of species. By contrast, exclusion of agricultural lands benefits representation of carbon storage within priority areas, as lands of high value for agriculture and carbon storage overlap little. When agricultural lands were included and equally weighted with biodiversity and carbon storage, a balanced representation resulted. Our findings suggest that with appropriate management, South American agroecosystems can significantly contribute to biodiversity conservation.     

OCP3 is an important modulator of NPR1-mediated jasmonic acid-dependent induced defenses in <Emphasis Type="Italic">Arabidopsis</Emphasis>

Background  

Upon appropriate stimulation, plants increase their level of resistance against future pathogen attack. This phenomenon, known as induced resistance, presents an adaptive advantage due to its reduced fitness costs and its systemic and broad-spectrum nature. In Arabidopsis, different types of induced resistance have been defined based on the signaling pathways involved, particularly those dependent on salicylic acid (SA) and/or jasmonic acid (JA).     

Physiological tonicity improves human chondrogenic marker expression through nuclear factor of activated T-cells 5 <Emphasis Type="Italic">in vitro</Emphasis>

Introduction  

Chondrocytes experience a hypertonic environment compared with plasma (280 mOsm) due to the high fixed negative charge density of cartilage. Standard isolation of chondrocytes removes their hypertonic matrix, exposing them to nonphysiological conditions. During in vitro expansion, chondrocytes quickly lose their specialized phenotype, making them inappropriate for cell-based regenerative strategies. We aimed to elucidate the effects of tonicity during isolation and in vitro expansion on chondrocyte phenotype.     

Survival of Escherichia coli O157:H7 in wastewater from dairy lagoons

AIM: To determine the survival of Escherichia coli O157:H7 in dairy wastewater from on-site holding lagoons equipped with or without circulating aerators. METHODS AND RESULTS: Survival was monitored in dairy lagoon microcosms equipped with or without scale-size circulators. Both laboratory strains of E. coli O157:H7 and an isolate of E. coli H7 from wastewater had poor survival rates and none proliferated in water from waste lagoons with or without circulators. Furthermore, the decline of E. coli O157:H7 was not enhanced in those microcosms equipped with circulators. Strain variation in survival was observed in both circulated and settling waters. The decline rate of E. coli O157:H7 Odwalla strain increased proportionately with the inoculum load. Escherichia coli failed to establish itself in wastewater even after four sequential inoculations simulating continuous faecal input into the lagoon. The native aerobic bacteria survived longer with a decimal reduction time of 21.3 days vs either introduced or native E. coli, which declined rapidly with decimal reduction time of 0.5-9.4 days. CONCLUSIONS: Escherichia coli O157:H7 failed to establish and proliferate in dairy wastewater microcosms equipped with or without circulating aerators. SIGNIFICANCE AND IMPACT OF THE STUDY: This study furthers our knowledge of pathogen survival in wastewater, and suggests that proper management of wastewater before its use in irrigation is essential to reduce pathogen transfer to crops.