A simple tool for calculating egg shape,volume and surface area from digital images

The geometrical properties of eggs – such as volume and surface area – have uses ranging from ecological, physiological and morphological studies in birds, to predictions of chick condition in the poultry industry. Although measurements of an egg's length and breadth can be used to approximate its geometry, the coefficients used in these models are specific to the original test population, and intraspecific variation in egg shape means these methods cannot be used reliably beyond that population. Here I present a novel mathematical formula to describe the curvature of a bird's egg that can be used to calculate the shape, volume and surface area of an egg precisely from digital images. Using data from several species I demonstrate that the model has a greater level of accuracy than length‐ and breadth‐based methods, and release the user‐friendly tool for others to use for measuring eggs from digital images.     

Chromosome profile ofLeishmania donovani: Interstrain and interspecific variations

The genome ofLeishmania donovani AG83, a virulent strain causing kala-azar, was resolved into 29 chromosomal bands by pulsed field gel electrophoresis (pFGE) under standardized conditions. Comparison of the karyotype with those of other strains and species revealed variations. By Southern hybridization, specific genes were localized to individual chromosomes. Twenty-two copies ofβ-tubulin genes are located on band 27 (1.63 Mb); minor copies are present in band 16 (850 kb) and band 9 (650 kb). Aβ-tubulin related nontranscribed locus was isolated from a genomic library and shown to contain repetitive sequences hybridizing throughout the genome. Single chromosomes contain multicopy clusters of gp63 and rnini-exon-derived RNA genes, but interspecific variations were observed in each case. The results emphasize the importance of using a standard reference strain ofLeishmania donovani for coordinated genome mapping of this clinically important organism.     

The effects of the presence of a dog in the classroom

Abstract

This study examined the effects of the presence of a dog in the classroom on field independence, social competence, empathy with animals and social-emotional atmosphere. The participants were 46 first-graders (43 of them immigrants) of two school classes (control and experimental). In the experimental group, a dog was present in the classroom for three months. Multivariate analyses revealed significant enhancement of field independence and empathy with animals in the experimental group in comparison to the control group (no dog). Thus, the presence of the dog fostered the development of autonomous functioning and a better segregation of self/non-self, which is the foundation of sensitivity towards the needs and moods of other people. Moreover, according to the views of the teachers, the children in the experimental group exhibited higher social integration, and there were fewer aggressive children, compared with the children in the control group. In sum, the results indicate that a dog can be an important factor in the social and cognitive development of children.     

Enhancement of the geomagnetic field reduces the phototaxis of rice brown planthopper Nilaparvata lugens associated with frataxin down‐regulation

The geomagnetic field (GMF) is an environmental cue that provides directional information for animals. The intensity of GMF is varied over space and time. Variations in the GMF intensity affect the navigation of animals and their physiology. In this study, the phototaxis of the migratory insect rice planthopper Nilaparvata lugens (N. lugens) and frataxin in N. lugens (Nl‐fh), which is a mitochondrial protein required for cellular iron homeostasis and iron‐sulfur cluster assembly, were investigated by using different intensities of magnetic field. From the results, individuals of N. lugens showed decreased phototaxis when reared and tested in a behavioral arena under a strong magnetic field. Besides the reduction in performance, an accompanying effect of the strong magnetic field condition was a reduced level of Nl‐fh‐messenger RNA, and a Nl‐fh knockdown indeed impaired the phototactic behavior in a tested sample of insects. This leads to the conclusion that the expression of frataxin is dependent on the strength of the surrounding magnetic field and that functional frataxin facilitates phototactic behavior in N. lugens.     

Taking a big bite: Working together to better understand the evolution of feeding in primates

The study of adaptation requires the integration of an array of different types of data. A single individual can find such integration daunting, if not impossible. In an effort to clarify the role of diet in the evolution of the primate craniofacial and dental apparatus, we assembled a team of researchers that have various types and degrees of expertise. This interaction has provided a range of insights for all contributors, and this has helped to refine questions, clarify the possibilities and limitations that laboratory and field settings offer, and further explore the ways in which laboratory and field data can be suitably integrated. A complete and accurate picture of dietary adaptation cannot be gained in isolation. Collaboration provides the bridge to a more holistic view of primate biology and evolution.     

An electrophoretic karyotype of Aspergillus niger

Summary An electrophoretic karyotype of Aspergillus niger was obtained using contour-clamped homogeneous electric field (CHEF) gel electrophoresis. Chromosomesized DNA was separated into four bands. Seven of the eight linkage groups could be correlated with specific chromosomal bands. For this purpose DNA preparations from seven transformant strains of A. niger each carrying the heterologous amdS gene of Aspergillus nidulans on a different chromosome were analysed. Some of the assignments were confirmed with linkage groupspecific A. niger probes. The estimated sizes of the A. niger chromosome range from 3.5 to 6.6 Mb, based on gel migration relative to the chromosomes of Schizosaccharomyces pombe strains, Saccharomyces cerevisiae and A. nidulans. The total genome size of A. niger significantly exceeds that of A. nidulans and is estimated to be about 35.5–38.5 Mb. Electrophoretic karyotyping was used to allocate non-mutant rRNA genes and to estimate the number of plasmids integrated in a high copy number transformant.     

The management of populations of vesicular-arbuscular mycorrhizal fungi in acid-infertile soils of a savanna ecosystem

A field trial was conducted at two sites in the savanna ecosystem of eastern Colombia to compare the effects of inoculation with vesicular-arbuscular mycorrhizal fungi (VAMF) ofBrachiaria dictyoneura (a tropical grass), cassava (Manihot esculenta), the tropical forage legume kudzu (Pueraria phaseoloides) andSorghum sp., and two phosphate sources. The second stage of the trial studied the effect of these pre-crop treatments on the subsequent growth, nutrition and VAM status of cowpea (Vigna unguiculata) andStylosanthes capitata in the following season, compared with both crops sown in native savanna. Inoculation significantly increased the levels of VAM and plant yields in the early growth stages of all crops during the first season, particularly with the rock phosphate (RP) source. The most significant increases were observed in the mycorrhiza-dependent cassava and kudzu crops up to 15 weeks after sowing, and were associated with increased foliar uptake of P and Mg. The effectiveness of the introduced inoculum was greater at the field site with a sandier soil. In the second season the levels of VAM in roots of cowpea andS. capitata were all increased significantly in pre-cropped plots compared with a savanna control. The increased presence of VAM was associated with significantly increased yields on plots previously sown to cassava, kudzu andSorghum sp. The data support the idea that increasing the VAMF inoculum potential of these acid-infertile soils by inoculation or pre-crops can greatly increase the rate of establishment of mycorrhiza-dependent host plants.