Intrastrain variants of herpes simplex virus type 1 isolated from a neonate with fatal disseminated infection differ in the ICP34.5 gene, glycoprotein processing, and neuroinvasiveness

Two intrastrain variants of herpes simplex virus type 1 (HSV-1) were isolated from a newborn with fatal disseminated infection. A small-plaque-producing variant (SP7) was the predominant virus (>99%) in the brain, and a large-plaque-producing variant (LP5) was the predominant virus (>99%) in the lung and gastrointestinal tract. EcoRI and BamHI restriction fragment patterns indicated that SP7 and LP5 are related strains. The large-plaque variants produced plaques similar in size to those produced by HSV-1 KOS. Unlike LP5 or KOS, SP7 was highly cell associated and processing of glycoprotein C and glycoprotein D was limited to precursor forms in infected Vero cells. The large-plaque phenotype from KOS could be transferred into SP7 by cotransfection of plasmids containing the EK or JK EcoRI fragment or a 3-kb plasmid with the UL34.5 gene of HSV-1 KOS together with SP7 DNA. PCR analysis using primers from within the ICP34.5 gene indicated differences for SP7, LP5, and KOS. Sequencing data indicated two sets of deletions in the UL34.5 gene that distinguish SP7 from LP5. Both SP7 and LP5 variants were neurovirulent (lethal following intracranial inoculation of young BALB/c mice); however, the LP5 variant was much less able to cause lethal neuroinvasive disease (footpad inoculation) whereas KOS caused no disease. Passage of SP7 selected for viruses (SLP-5 and SLP-10) which were attenuated for lethal neuroinvasive disease, were not cell-associated, and differed in the UL34.5 gene. UL34.5 from SLP-5 or SLP-10 resembled that of KOS. These findings support a role for UL34.5 in promoting virus egress and for neuroinvasive disease.     

Colonization of new host plant individuals by locally adapted thrips

This study considered the dispersal and subsequent reproduction of Apterothrips aptens a wingless, folivorous thrips species that is divided into local populations, each adapted to its individual host plant We placed host plants with no thrips into the field and observed the rate at which thrips colonized these plants Colonization events were rare, on average each pot received 1 47 immigrants during the year Immature thrips were found associated with 64 59c of these events, indicating that reproduction had occurred Colonization was most likely to occur during the summer Most colonists walked onto the new host and airborne movements were very rare Plants that were located far from near neighbors were less likely to be colonized although the size of nearby source populations did not influence the rate of colonization
These results suggest that limited movement is associated with division of this population into isolated demes Limited movement appeared to be more important as a barner to successful colonization than was demographic success following arrival at a new host plant     

Plant behaviour and communication

Plant behaviours are defined as rapid morphological or physiological responses to events, relative to the lifetime of an individual. Since Darwin, biologists have been aware that plants behave but it has been an underappreciated phenomenon. The best studied plant behaviours involve foraging for light, nutrients, and water by placing organs where they can most efficiently harvest these resources. Plants also adjust many reproductive and defensive traits in response to environmental heterogeneity in space and time. Many plant behaviours rely on iterative active meristems that allow plants to rapidly transform into many different forms. Because of this modular construction, many plant responses are localized although the degree of integration within whole plants is not well understood. Plant behaviours have been characterized as simpler than those of animals. Recent findings challenge this notion by revealing high levels of sophistication previously thought to be within the sole domain of animal behaviour. Plants anticipate future conditions by accurately perceiving and responding to reliable environmental cues. Plants exhibit memory, altering their behaviours depending upon their previous experiences or the experiences of their parents. Plants communicate with other plants, herbivores and mutualists. They emit cues that cause predictable reactions in other organisms and respond to such cues themselves. Plants exhibit many of the same behaviours as animals even though they lack central nervous systems. Both plants and animals have faced spatially and temporally heterogeneous environments and both have evolved plastic response systems.     

A method for aligning RNA secondary structures and its application to RNA motif detection

Background  

Alignment of RNA secondary structures is important in studying functional RNA motifs. In recent years, much progress has been made in RNA motif finding and structure alignment. However, existing tools either require a large number of prealigned structures or suffer from high time complexities. This makes it difficult for the tools to process RNAs whose prealigned structures are unavailable or process very large RNA structure databases.     

Facilitation of tiger moths by outbreaking tussock moths that share the same host plants

1.?Ecologists have argued about the commonness and strength of interspecific competition between insect herbivores, but facilitation between herbivores has received much less consideration. We previously found that when two species of folivorous caterpillars co-occurred on a shared host plant, feeding by early season tiger moth caterpillars reduced the growth and reproduction of later season tussock caterpillars. However, densities of tussock caterpillars in summer were positively correlated with densities of tiger moth caterpillars the following spring. 2.?In this study, we experimentally manipulated numbers of feeding tussock caterpillars and found that they facilitated tiger moth caterpillars. 3.?The depth of the litter layer beneath host lupine bushes was positively correlated with the number of tussock caterpillars feeding on each bush. Experimental additions of litter beneath lupine canopies during summer resulted in increased numbers of tiger moth caterpillars in the following spring, indicating a causal role of litter. Litter potentially provides food, habitat and protection from desiccation and predation. We failed to find evidence that tussock caterpillars facilitated tiger moth caterpillars by mechanisms independent of litter. 4.?Our study demonstrates that facilitation may operate between insect herbivores, across life-stages through indirect interactions that are non-trophic. Facilitation operated by a novel mechanism, the accumulation of litter which was a by-product of feeding by one species was valuable to a second species. Facilitation persisted in time and space far beyond the creation of litter by tussock caterpillars which should be considered important ecosystem engineers from the point of view of tiger moths. Facilitations that involve habitat modification may generally connect species that do not interact directly or trophically, and have not previously been considered to affect one another.     

Complex consequences of herbivory and interplant cues in three annual plants

Information exchange (or signaling) between plants following herbivore damage has recently been shown to affect plant responses to herbivory in relatively simple natural systems. In a large, manipulative field study using three annual plant species (Achyrachaena mollis, Lupinus nanus, and Sinapis arvensis), we tested whether experimental damage to a neighboring conspecific affected a plant's lifetime fitness and interactions with herbivores. By manipulating relatedness between plants, we assessed whether genetic relatedness of neighboring individuals influenced the outcome of having a damaged neighbor. Additionally, in laboratory feeding assays, we assessed whether damage to a neighboring plant specifically affected palatability to a generalist herbivore and, for S. arvensis, a specialist herbivore. Our study suggested a high level of contingency in the outcomes of plant signaling. For example, in the field, damaging a neighbor resulted in greater herbivory to A. mollis, but only when the damaged neighbor was a close relative. Similarly, in laboratory trials, the palatability of S. arvensis to a generalist herbivore increased after the plant was exposed to a damaged neighbor, while palatability to a specialist herbivore decreased. Across all species, damage to a neighbor resulted in decreased lifetime fitness, but only if neighbors were closely related. These results suggest that the outcomes of plant signaling within multi-species neighborhoods may be far more context-specific than has been previously shown. In particular, our study shows that herbivore interactions and signaling between plants are contingent on the genetic relationship between neighboring plants. Many factors affect the outcomes of plant signaling, and studies that clarify these factors will be necessary in order to assess the role of plant information exchange about herbivory in natural systems.     

Damage to sagebrush attracts predators but this does not reduce herbivory

Emissions of volatiles increase following herbivory from many plant species and volatiles may serve multiple functions. Herbivore‐induced volatiles attract predators and parasitoids of herbivores and are often assumed to benefit plants by facilitating top‐down control of herbivores; this benefit of induced emissions has been tested only a few times. Volatile compounds released by experimentally clipped sagebrush shoots have been shown to reduce levels of chewing damage experienced by other shoots on the same plant and on neighboring sagebrush plants. In this study, I asked whether experimental clipping attracted predators of herbivorous insects to sagebrush shoots. I also evaluated aphid populations and chewing damage on clipped and unclipped shoots and whether predators were likely to have caused differences in aphids and chewing damage. Shoots that had been clipped recruited more generalist predators, particularly coccinellids and Geocoris spp. in visual surveys conducted during two seasons. Clipping also caused increased numbers of parasitized aphids in one season. Ants were common tending aphids but were not significantly affected by clipping. Despite the increase in generalist predators, clipped plants were more likely to support populations of aphids that increased during both seasons compared to aphids on unclipped control plants. Clipped shoots suffered less damage by chewing herbivores in the 1‐year in which this was measured. Chewing damage was not correlated with numbers of predators. These results suggest that predators and parasitoids were attracted to experimentally clipped sagebrush plants but that these predators were not effective at reducing net damage to the plant. This conclusion is not surprising as much of the herbivory is inflicted by grasshoppers and deer, herbivores that are not vulnerable to the predators attracted to sagebrush volatiles. More generally, it should not be assumed that predators that are attracted by herbivore‐induced volatiles necessarily benefit the plant without testing this hypothesis under field conditions.     

Effects of experimental watering but not warming on herbivory vary across a gradient of precipitation

Climate change can affect biotic interactions, and the impacts of climate on biotic interactions may vary across climate gradients. Climate affects biotic interactions through multiple drivers, although few studies have investigated multiple climate drivers in experiments. We examined the effects of experimental watering, warming, and predator access on leaf water content and herbivory rates of woolly bear caterpillars (Arctia virginalis) on a native perennial plant, pacific silverweed (Argentina anserina ssp. pacifica), at two sites across a gradient of precipitation in coastal California. Based on theory, we predicted that watering should increase herbivory at the drier end of the gradient, predation should decrease herbivory, and watering and warming should have positive interacting effects on herbivory. Consistent with our predictions, we found that watering only increased herbivory under drier conditions. However, watering increased leaf water content at both wetter and drier sites. Warming increased herbivory irrespective of local climate and did not interact with watering. Predation did not affect herbivory rates. Given predictions that the study locales will become warmer and drier with climate change, our results suggest that the effects of future warming and drying on herbivory may counteract each other in drier regions of the range of Argentina anserina. Our findings suggest a useful role for range‐limit theory and the stress‐gradient hypothesis in predicting climate change effects on herbivory across stress gradients. Specifically, if climate change decreases stress, herbivory may increase, and vice versa for increasing stress. In addition, our work supports previous suggestions that multiple climate drivers are likely to have dampening effects on biotic interactions due to effects in different directions, though this is context‐dependent.