Structural basis for the coiled-coil architecture of human CtIP

The DNA repair factor CtIP has a critical function in double-strand break (DSB) repair by homologous recombination, promoting the assembly of the repair apparatus at DNA ends and participating in DNA-end resection. However, the molecular mechanisms of CtIP function in DSB repair remain unclear. Here, we present an atomic model for the three-dimensional architecture of human CtIP, derived from a multi-disciplinary approach that includes X-ray crystallography, small-angle X-ray scattering (SAXS) and diffracted X-ray tracking (DXT). Our data show that CtIP adopts an extended dimer-of-dimers structure, in agreement with a role in bridging distant sites on chromosomal DNA during the recombinational repair. The zinc-binding motif in the CtIP N-terminus alters dynamically the coiled-coil structure, with functional implications for the long-range interactions of CtIP with DNA. Our results provide a structural basis for the three-dimensional arrangement of chains in the CtIP tetramer, a key aspect of CtIP function in DNA DSB repair.     

Linking intronic polymorphism on the CHD1‐Z gene with fitness correlates in Black‐tailed Godwits Limosa l. limosa

We show that variation in an intronic length polymorphism in the CHD1‐Z gene in Black‐tailed Godwits Limosa l. limosa is associated with fitness correlates. This is the second example of the CHDZ‐1 gene being correlated with fitness, a previous study having established that Moorhens Gallinula chloropus carrying the rare Z* allele have reduced survival. In Godwits, however, carriers of the Z* allele (374 bp) fared better than those with the more frequent Z allele (378 bp) with respect to body mass, plumage ornamentation, reproductive parameters and habitat quality. The Z* allele was found in 14% of 251 adult birds from nature reserves, but was absent from 33 birds breeding in intensively managed agricultural lands. Males and females with the Z* allele had less extensive breeding plumage, and females had a higher body mass, bred earlier and had larger eggs. There were no significant differences in annual survival between birds with and without the Z* allele. DNA isolated from museum skins demonstrated that this polymorphism was present at low frequency in 1929. We speculate that strong asymmetrical overdominance may explain the low frequency of the Z* allele and that genetic linkage to causal genes might be an explanation for the phenotypic correlations. Our findings suggest a degree of cryptic genetic population structuring in the Dutch Godwit population.     

Genetic structure and differentiation of the Japanese extremely long-tailed chicken breed (Onagadori), associated with plumage colour variation: suggestions for its management and conservation

The Onagadori is a distinguished chicken breed that is characterized by an extremely long tail in the male. In this breed, three different plumage colour varieties have been developed (black-breasted white, black-breasted red and white) in which the black-breasted white is believed to be the original colour of the Onagadori, based on historical records. To establish a conservation strategy, 176 birds were genotyped for autosomal microsatellites. Significant genetic distinctness was found between the original (black-breasted white) and two derivative varieties ( F _ST = 0.091 and 0.093). At the same time, a Bayesian model-based clustering revealed that the majority of individuals belonging to the black-breasted red and white varieties had an extremely low proportion of the genome shared with the original type (black-breasted white). This suggests that derivative varieties were created by crossing with other breeds, with low introgression of the original-type genome. We propose that the three plumage colour varieties should be treated as separate genetic units in a conservation programme.     

The endosperm development and the variations of structures of embryo sacs: unravelling the low fecundity of Zephyranthes candida (Amaryllidaceae)

To unravel a low fecundity in Zephyranthes candida (Lindl.) Herb., the development of the endosperm was studied using conventional paraplast section technique. The results show that the endosperm develops normally and comprises four major stages viz. syncytial, cellularization, differentiation and maturation. Both proliferation of antipodal cells and their close contact with the primary endosperm nucleus were observed, which should favor transportation of nutrients and accelerate development of embryo and endosperm. In Z. candida, at least four events of nuclear migration occurred during the course of embryogenesis and endosperm development. The 12.7% structurally and functionally abnormal ovules, along with the 22.3% collapsed and aborted ovules observed accounts for the low fecundity to some extent.     

SPATIAL FLOWER PARAMETERS AND INSECT SPATIAL VISION

The present article reviews recent and older literature on the spatial parameters that flowers display, as well as on the capacities of anthophilous insects to perceive and use these parameters for optimizing their foraging success. Although co-evolution of plants and pollinators has frequently been discussed with respect to floral colours and insect colour vision, it has rarely been assessed with respect to insect spatial vision and spatial floral cues, such as shape, pattern, size, contrast, symmetry, spatial frequency, contour density and orientation of contours. This review is an attempt to fill this gap. From experimental findings and observations on both flowers and insects, we arrive at the conclusion that all of the spatial and spatio-temporal parameters that flowers offer are relevant to the foraging task and are tuned to the insect's visual capacities and visually guided behaviour. We try, in addition, to indicate that temporal cues are closely related to spatial cues, and must therefore be included when flower–pollinator interactions are examined. We include results that show that colour vision and spatial vision have diverged over the course of evolution, particularly regarding the processing of spatio-temporal information, but that colour vision plays a role in the processing of spatial cues that are independent of temporal parameters. By presenting this review we hope to contribute to closer collaboration among scientists working in the vast fields of botany, ecology, evolution, ethology and sensory physiology.     

Oecophylla smaragdina food conversion efficiency: prospects for ant farming

Oecophylla ants are sold at high prices on several commercial markets as a human delicacy, as pet food or as traditional medicine. Currently markets are supplied by ants collected from the wild; however, an increasing interest in ant farming exists as all harvest is easily sold and as ant farming can be combined with the use of the ants in biological control programmes in tropical plantations where pest insects are converted into ant biomass. To assess the cost‐benefits of ant farming based on artificial feeding, food consumption and food conversion efficiency (ECI) of Oecophylla smaragdina (Fabricius) was tested under laboratory conditions. Of the two types of food offered, the ants ingested 76% pure sucrose and 24% insect prey (dry weights) leading to ECI’s of 29% and 39% including brood only or brood plus imago gain, respectively. Based on Thai sugar and protein food costs and ant brood selling prices these efficiencies led to rates of return from 1.52 to 4.56, respectively, if: (i) protein is supplied from commercial products; or (ii) alternatively supplied from free sources such as insects and kitchen waste. These results suggest that Oecophylla ant farming may become highly profitable and deserves further research.     

Effects of Alpine land‐use changes: Soil macrofauna community revisited

Although soil invertebrates play a decisive role in maintaining ecosystem functioning, little is known about their structural composition in Alpine soils and how their abundances are affected by the currently ongoing land‐use changes. In this study, we re‐assessed the soil macrofauna community structure of managed and abandoned Alpine pastureland, which has already been evaluated 14 years earlier. Our results confirm clear shifts in the community composition after abandonment, in that (1) Chilopoda and Diplopoda were recorded almost exclusively on the abandoned sites, (2) Coleoptera larvae and Diptera larvae were more abundant on the abandoned than on the managed sites, whereas (3) Lumbricidae dominated on the managed sites. By revisiting managed and abandoned sites, we infer community patterns caused by abandonment such as changes in the epigeic earthworm community structure, and we discuss seasonal and sampling effects. Our case study improves the still limited understanding of spatio‐temporal biodiversity patterns of Alpine soil communities.