Destination‐based seed dispersal homogenizes genetic structure of a tropical palm

As the dominant seed dispersal agents in many ecosystems, frugivorous animals profoundly impact gene movement and fine‐scale genetic structure of plants. Most frugivores engage in some form of destination‐based dispersal, in that they move seeds towards specific destinations, resulting in clumped distributions of seeds away from the source tree. Molecular analyses of dispersed seeds and seedlings suggest that destination‐based dispersal may often yield clusters of maternal genotypes and lead to pronounced local genetic structure. The long‐wattled umbrellabird Cephalopterus penduliger is a frugivorous bird whose lek mating system creates a species‐specific pattern of seed dispersal that can potentially be distinguished from background dispersal processes. We used this system to test how destination‐based dispersal by umbrellabirds into the lek affects gene movement and genetic structure of one of their preferred food sources Oenocarpus bataua, a canopy palm tree. Relative to background dispersal processes, umbrellabird mating behaviour yielded more diverse seed pools in leks that included on average five times more seed sources and a higher incidence of long‐distance dispersal events. This resulted in markedly lower fine‐scale spatial genetic structure among established seedlings in leks than background areas. These species‐specific impacts of destination‐based dispersal illustrate how detailed knowledge of disperser behaviour can elucidate the mechanistic link driving observed patterns of seed movement and genetic structure.     

Relationships among msx gene structure and function in zebrafish and other vertebrates

The zebrafish genome contains at least five msx homeobox genes, msxA, msxB, msxC, msxD, and the newly isolated msxE. Although these genes share structural features common to all Msx genes, phylogenetic analyses of protein sequences indicate that the msx genes from zebrafish are not orthologous to the Msx1 and Msx2 genes of mammals, birds, and amphibians. The zebrafish msxB and msxC are more closely related to each other and to the mouse Msx3. Similarly, although the combinatorial expression of the zebrafish msx genes in the embryonic dorsal neuroectoderm, visceral arches, fins, and sensory organs suggests functional similarities with the Msx genes of other vertebrates, differences in the expression patterns preclude precise assignment of orthological relationships. Distinct duplication events may have given rise to the msx genes of modern fish and other vertebrate lineages whereas many aspects of msx gene functions during embryonic development have been preserved.      

Transgenic tobacco plants expressing Tarin 1 inhibit the growth of Pseudomonas syringae pv. tomato and the development of Spodoptera frugiperda

The protein Tarin 1, from Colocasia esculenta, was expressed in Nicotiana tabacum. Bioassays were done on plants expressing Tarin 1 at different levels using Spodoptera frugiperda larvae, various bacteria and fungi and the root‐knot nematode Meloidogyne javanica. It was found that S. frugiperda larvae fed on transformed plants had retarded and lower pupation, lower accumulated biomass and higher mortality rate than larvae fed on control plants. Also, Tarin 1 was found to inhibit the growth in vitro of Pseudomonas syringae pv. tomato. For Meloidogyne javanica, both relative replication and root damage were greater in control plants than in transformed plants, but the results were not statistically significant. This work illustrates the effects of plants expressing Tarin 1, on the growth and development of insects and bacteria, and shows its potential for pest management.     

In vivo uptake of a haem analogue Zn protoporphyrin IX by the human malaria parasite P. falciparum‐infected red blood cells

The cellular traffic of haem during the development of the human malaria parasite Plasmodium falciparum, through the stages R (ring), T (trophozoite) and S (schizonts), was investigated within RBC (red blood cells). When Plasmodium cultures were incubated with a fluorescent haem analogue, ZnPPIX (Zn protoporphyrin IX) the probe was seen at the cytoplasm (R stage), and the vesicle‐like structure distribution pattern was more evident at T and S stages. The temporal sequence of ZnPPIX uptake byP. falciparum‐infected erythrocytes shows that at R and S stages, a time‐increase acquisition of the porphyrin reaches the maximum fluorescence distribution after 60 min; in contrast, at the T stage, the maximum occurs after 120 min of ZnPPIX uptake. The difference in time‐increase acquisition of the porphyrin is in agreement with a maximum activity of haem uptake at the T stage. To gain insights into haem metabolism, recombinant PfHO (P. falciparum haem oxygenase) was expressed, and the conversion of haem into BV (biliverdin) was detected. These findings point out that, in addition to haemozoin formation, the malaria parasite P. falciparum has evolved two distinct mechanisms for dealing with haem toxicity, namely, the uptake of haem into a cellular compartment where haemozoin is formed and HO activity. However, the low Plasmodium HO activity detected reveals that the enzyme appears to be a very inefficient way to scavenge the haem compared with the Plasmodium ability to uptake the haem analogue ZnPPIX and delivering it to the food vacuole.     

Are behavioural responses to predation cues linked across life cycle stages?

1. Prey organisms can perceive cues to predation hazard and adopt low‐risk behaviours to increase survival. Animals with complex life cycles, such as insects, can exhibit such anti‐predatory behaviours in multiple life stages. 2. Cues to predation risk may induce ovipositing females to choose habitats with low predation risk. Cues to predation risk may also induce larvae to adopt facultative behaviours that reduce risk of predation. 3. One hypothesis postulates that anti‐predation behaviours across adult and larval stages may be negatively associated because selection for effective anti‐predator behaviour in one stage leads to reduced selection for avoidance of predators in other stages. An alternative hypothesis suggests that selection by predation favours multi‐component defences, with both avoidance of oviposition and facultative adoption of low‐risk behaviours by larvae. 4. Laboratory and field experiments were used to determine whether defensive responses of adult and larval mosquitoes are positively or negatively associated. The study tested effects of waterborne cues from predatory Toxorhynchites theobaldi on oviposition choices and larval behaviours of three of its common prey: Culex mollis, Limatus durhamii and Aedes albopictus. 5. Culex mollis shows strong anti‐predator responses in both life stages, consistent with the hypothesis of a multi‐component behavioural defence. The other two species showed no detectable responses to waterborne predator cues in either adult or larval stages. Larvae of these unresponsive species were significantly more vulnerable to this predator than was C. mollis. 6. For these mosquitoes, species appear either to have been selected for multi‐component defences against predation or to act in ways that could be called predator‐naïve.     

Unbiased descriptor and parameter selection confirms the potential of proteochemometric modelling

Background  

Proteochemometrics is a new methodology that allows prediction of protein function directly from real interaction measurement data without the need of 3D structure information. Several reported proteochemometric models of ligand-receptor interactions have already yielded significant insights into various forms of bio-molecular interactions. The proteochemometric models are multivariate regression models that predict binding affinity for a particular combination of features of the ligand and protein. Although proteochemometric models have already offered interesting results in various studies, no detailed statistical evaluation of their average predictive power has been performed. In particular, variable subset selection performed to date has always relied on using all available examples, a situation also encountered in microarray gene expression data analysis.     

Summer distribution of Red-legged Partridges Alectoris rufa in relation to water availability on Mediterranean farmland

The suggestion that the summer distribution of Red-legged Partridges Alectoris rufa in the Mediterranean region is determined by the availability of surface water was examined on the agricultural farm, Alto Alentejo, southern Portugal. Partridge coveys were surveyed between 15 July and 15 August in 1993 and 1994. Using a vector-based Geographic Information System, we assessed, for each covey location and for the locations of a double number of random points, the distance to the nearest water point, distance to field boundaries, distance to water lines and land use classes. Univariate comparisons were made between the two groups of locations, and three multivariate logistic models were fitted through forward stepwise selection to the 1993, 1994 and pooled data sets to estimate the probability of sighting partridge coveys in the study area. Distance to water was significantly lower for partridge locations than for random points in both years and was the only variable selected for all logistic models. Apart from water availability, Red-legged Partridge locations were also affected by land use and distance to field boundaries.     

Long-term persistence of infectious Zika virus: Inflammation and behavioral sequela in mice

The neurodevelopmental defects associated with ZIKV infections early in pregnancy are well documented, however the potential defects and long-term consequences associated with milder infections in late pregnancy and perinatal period are less well understood. To model these, we challenged 1 day old (P1) immunocompetent C57BL/6 mice with ZIKV. The animals developed a transient neurological syndrome including unsteady gait, kinetic tremors, severe ataxia and seizures 10–15 days post-infection (dpi) but symptoms subsided after a week, and most animals survived. Despite apparent recovery, MRI of convalescent mice show reduced cerebellar volume that correlates with altered coordination and motor function as well as hyperactivity and impulsivity. Persistent mRNA levels of pro-inflammatory genes including Cd80, Il-1α, and Ifn-γ together with Cd3, Cd8 and perforin (PrfA), suggested persistence of low-grade inflammation. Surprisingly, the brain parenchyma of convalescent mice harbor multiple small discrete foci with viral antigen, active apoptotic processes in neurons, and cellular infiltrates, surrounded by activated astrocytes and microglia as late as 1-year post-infection. Detection of negative-sense strand viral RNA and isolation of infectious virus derived from these convalescent mice by blinded passage in Vero cells confirmed long-term persistence of replicating ZIKV in CNS of convalescent mice. Although the infection appears to persist in defined reservoirs within CNS, the resulting inflammation could increase the risk of neurodegenerative disorders. This raises concern regarding possible long-term effects in asymptomatic children exposed to the virus and suggests that long-term neurological and behavioral monitoring as well as anti-viral treatment to clear virus from the CNS may be useful in patients exposed to ZIKV at an early age.     

An improved microbial synthesis of purine nucleosides

E. coliBL21 synthesized purine nucleosides from pyrimidine ones. A 94% yield of adenosine from uridine was reached within 1 h.