Draft genome sequences of type VI secretion system-encoding vibrio fischeri strains FQ-A001 and ES401

The type VI secretion system (T6SS) facilitates lethal competition between bacteria through direct contact. Comparative genomics has facilitated the study of these systems in Vibrio fischeri, which colonizes the squid host Euprymna scolopes. Here, we report the draft genome sequences of two lethal V. fischeri strains that encode the T6SS, FQ-A001 and ES401

Bacterial symbionts use a type VI secretion system to eliminate competitors in their natural host

Intraspecific competition describes the negative interaction that occurs when different populations of the same species attempt to fill the same niche. Such competition is predicted to occur among host-associated bacteria but has been challenging to study in natural biological systems. Although many bioluminescent Vibrio fischeri strains exist in seawater, only a few strains are found in the light-organ crypts of an individual wild-caught Euprymna scolopes squid, suggesting a possible role for intraspecific competition during early colonization. Using a culture-based assay to investigate the interactions of different V. fischeri strains, we found “lethal” and “nonlethal” isolates that could kill or not kill the well-studied light-organ isolate ES114, respectively. The killing phenotype of these lethal strains required a type VI secretion system (T6SS) encoded in a 50-kb genomic island. Multiple lethal and nonlethal strains could be cultured from the light organs of individual wild-caught adult squid. Although lethal strains eliminate nonlethal strains in vitro, two lethal strains could coexist in interspersed microcolonies that formed in a T6SS-dependent manner. This coexistence was destabilized upon physical mixing, resulting in one lethal strain consistently eliminating the other. When juvenile squid were coinoculated with lethal and nonlethal strains, they occupied different crypts, yet they were observed to coexist within crypts when T6SS function was disrupted. These findings, using a combination of natural isolates and experimental approaches in vitro and in the animal host, reveal the importance of T6SS in spatially separating strains during the establishment of host colonization in a natural symbiosis

Interaction of climate change with effects of conspecific and heterospecific density on reproduction

We studied the relationship between temperature and the coexistence of great tit Parus major and blue tit Cyanistes caeruleus, breeding in 75 study plots across Europe and North Africa. We expected an advance in laying date and a reduction in clutch size during warmer springs as a general response to climate warming and a delay in laying date and a reduction in clutch size during warmer winters due to density-dependent effects. As expected, as spring temperature increases laying date advances and as winter temperature increases clutch size is reduced in both species. Density of great tit affected the relationship between winter temperature and laying date in great and blue tit. Specifically, as density of great tit increased and temperature in winter increased both species started to reproduce later. Density of blue tit affected the relationship between spring temperature and blue and great tit laying date. Thus, both species start to reproduce earlier with increasing spring temperature as density of blue tit increases, which was not an expected outcome, since we expected that increasing spring temperature should advance laying date, while increasing density should delay it cancelling each other out. Climate warming and its interaction with density affects clutch size of great tits but not of blue tits. As predicted, great tit clutch size is reduced more with density of blue tits as temperature in winter increases. The relationship between spring temperature and density on clutch size of great tits depends on whether the increase is in density of great tit or blue tit. Therefore, an increase in temperature negatively affected the coexistence of blue and great tits differently in both species. Thus, blue tit clutch size was unaffected by the interaction effect of density with temperature, while great tit clutch size was affected in multiple ways by these interactions terms

Clutch-size variation in Western Palaearctic secondary hole-nesting passerine birds in relation to nest box design

* Secondary hole-nesting birds that do not construct nest holes themselves and hence regularly breed in nest boxes constitute important model systems for field studies in many biological disciplines with hundreds of scientists and amateurs involved. Those research groups are spread over wide geographic areas that experience considerable variation in environmental conditions, and researchers provide nest boxes of varying designs that may inadvertently introduce spatial and temporal variation in reproductive parameters. * We quantified the relationship between mean clutch size and nest box size and material after controlling for a range of environmental variables in four of the most widely used model species in the Western Palaearctic: great tit Parus major, blue tit Cyanistes caeruleus, pied flycatcher Ficedula hypoleuca and collared flycatcher F. albicollis from 365 populations and 79 610 clutches. * Nest floor area and nest box material varied non-randomly across latitudes and longitudes, showing that scientists did not adopt a random box design. Clutch size increased with nest floor area in great tits, but not in blue tits and flycatchers. Clutch size of blue tits was larger in wooden than in concrete nest boxes. * These findings demonstrate that the size of nest boxes and material used to construct nest boxes can differentially affect clutch size in different species. The findings also suggest that the nest box design may affect not only focal species, but also indirectly other species through the effects of nest box design on productivity and therefore potentially population density and hence interspecific competition. [KEYWORDS: geographic location habitat latitude longitude nest box floor area nest box material

Clutch-size variation in Western Palaearctic secondary hole-nesting passerine birds in relation to nest box design

* Secondary hole-nesting birds that do not construct nest holes themselves and hence regularly breed in nest boxes constitute important model systems for field studies in many biological disciplines with hundreds of scientists and amateurs involved. Those research groups are spread over wide geographic areas that experience considerable variation in environmental conditions, and researchers provide nest boxes of varying designs that may inadvertently introduce spatial and temporal variation in reproductive parameters. * We quantified the relationship between mean clutch size and nest box size and material after controlling for a range of environmental variables in four of the most widely used model species in the Western Palaearctic: great tit Parus major, blue tit Cyanistes caeruleus, pied flycatcher Ficedula hypoleuca and collared flycatcher F. albicollis from 365 populations and 79 610 clutches. * Nest floor area and nest box material varied non-randomly across latitudes and longitudes, showing that scientists did not adopt a random box design. Clutch size increased with nest floor area in great tits, but not in blue tits and flycatchers. Clutch size of blue tits was larger in wooden than in concrete nest boxes. * These findings demonstrate that the size of nest boxes and material used to construct nest boxes can differentially affect clutch size in different species. The findings also suggest that the nest box design may affect not only focal species, but also indirectly other species through the effects of nest box design on productivity and therefore potentially population density and hence interspecific competition. [KEYWORDS: geographic location habitat latitude longitude nest box floor area nest box material]

Variation in clutch size in relation to nest size in birds.

Peer reviewe

The quality of life of children and adolescents with X-linked agammaglobulinemia

INTRODUCTION: The health-related quality of life in X-linked agammaglobulinemia was investigated in 25 children and adolescents patients through the Italian version of Pediatric Quality of Life Inventory 4.0 Generic Core Scale for patients aged less then 18 years, comparing child perception to that of the parents and the physician's evaluation. The data were compared with the ones of 80 healthy controls and the literature data of a group of patients with rheumatic diseases. DISCUSSION: The agammaglobulinemia subjects perceived a lower global quality of life than the healthy subjects, but significantly higher than the rheumatic diseases controls. The clinical relevance of health-related quality of life assessment in X-linked agammaglobulinemia pediatric patients is discussed