Melanocytes Fail to Survive in Hair Bulbs of the Shiba Goat (Capra hircus) With the Dominant Black-Eyed White Phenotype

Dominant black-eyed white phenotypes are one of the most commonly observed traits in domestic animals. Their genetic control mechanisms, however, have not been elucidated. As the first step to approach the problem, we examined histologically the patterns of the distribution of pigment cells in Shiba goats (two each of day-73-postcoitum and day-112-postcoitum fetuses, and a 15-week-old kid) with the dominant black-eyed white phenotype. Melanocytes were present and fully pigmented in the choroid and the sclera of eyes, as well as in dorsal skin epidermis of the fetuses and of the kid. Melanocytes were also found in approximately 6% of the hair bulbs in the fetal dorsal skin, while the rest (94%) lacked them. Hair follicles of the kid did not harbor melanocytes except for some in the early anagen stage. The results suggest that the survival of melanocytes was inhibited specifically in the hair follicles of the Shiba goat with the dominant black-eyed white phenotype and that the ostensibly similar phenotypes in the Shiba goat and in the SI or W mutants of the mouse, where melanocytes die en route to the hair bulbs, are regulated by different mechanisms.     

Group composition and contributions to breeding by Rufous Vangas Schetba rufa in Madagascar

The social system of the Rufous Vanga Schetba rufa was studied in a deciduous dry forest in Ampijoroa, western Madagascar. The species lived in groups of two to four individuals. Groups typically contained one adult female, one or two adult males and sometimes a (presumed) immature. All group members appeared to defend the territory. The presumed immatures had spotted throats and were smaller than adults in body size. They helped feed young and guard the nest but did not incubate or brood.     

Cytokinin Activity of Benzoylaminodeazapurines, Pentanoylaminodeazapurines and their Corresponding Purine Analogs in Five Bioassays

Cytokinin activities of 6-benzoylamino-1, 6-benzoylamino-3-, 6-pentanoylamino-1- and 6-pentanoylamino-3-deazapurines and their corresponding purine analogs, 6-benzoylaminopurine and 6-pentanoylaminopurine, were examined using five bioassay systems, tobacco callus growth, bud formation on tobacco callus, lettuce seed germination, fresh weight increase of radish cotyledons and retardation of chlorophyll degradation in radish cotyledons. 6-Benzoylamino- and 6-pentanoylamino-1-deazapurines showed stronger cytokinin activity than their corresponding purine analogs in all bioassays used. In tobacco callus growth, 6-benzoylamino-1-deazapurine was nearly as active as zeatin, one of the most active adenylate cytokinins. On the other hand, 6-benzoylamino- and 6-pentanoylamino-3-deazapurines were as active as or less active than corresponding purine analogs.     

Assessment of diet choice by the yellow fever mosquito Aedes aegypti

To investigate feeding‐related decisions in Aedes aegypti (L.), adults are presented with simple diets of paired gustatory stimuli conveying information concerning energy content, nutrient richness, osmotic balance and food toxicity in a two‐diet matrix assay. Assessment of mosquito gut contents indicates that both sexes accept single sugar diets in a dose‐dependent manner. When presented with a choice between two different yet equimolar sugar solutions, more individuals of both sexes accept the disaccharides, sucrose and trehalose, than the monosacharrides, fructose and glucose. The combination of pyranose and furanose sugars in solution, either physically associated (as in sucrose) or present as monomers (as glucose and fructose), is accepted over solutions containing a single sugar moiety. Using the two‐diet matrix assay, mosquito diet‐choice is also tested between two equimolar sucrose ‘driver’ solutions in which one is presented with various concentrations of another potential feeding cue ‘test’ compound (i.e. each of the 20 naturally‐occurring amino acids, sodium chloride, quinine or caffeine). Diet‐choice between the ‘driver’ sucrose‐only solution and the solution of the ‘driver’ sucrose containing a ‘test’ amino acid is influenced by sex, amino acid concentration and sucrose concentration. There is also an example of synergism between the diet components, leucine and sucrose. Mosquitoes demonstrate a dose‐dependent acceptance of sucrose‐only diets over sodium chloride‐containing sucrose when presented together. Interestingly, the sucrose‐only diet is accepted by more mosquitoes than all concentrations of the saline‐containing sucrose diets except those approximately isotonic to mosquito haemolymph, at which concentration mosquitoes show no clear choice between the diets. More individuals of both sexes accept sucrose‐only diets than the diets of caffeine‐containing sucrose in a dose‐dependent manner. Only females, however, respond to quinine‐containing sucrose diets and modulate this behaviour in relation to the energetic reward: more females imbibed quinine‐containing sucrose at the higher sucrose concentration (1 m ). A systematic characterization of diet selection behaviour of A. aegypti is presented for 27 putative feeding cues potentially involved in nectar/honeydew feeding. This study will be used as a basis from which to investigate further the mosquito's assessment of food quality and ultimately host choice.     

Comparative foraging ecology of Madagascar vangids (Vangidae)

The Vangidae, an endemic family in Madagascar, contains 14 species in 11 genera. The foraging behaviour of 13 species of vangids was investigated during the periods August-November 1989 and September-November 1990. These vangids are grouped into six bill types according to their bill shape, using the analogy of gripping tools: (1) forceps. (2) radio pliers, (3) strong pinchers, (4) pliers, (5) standard and (6) flat forceps types. We recognized seven foraging niches: (A) canopy-gleaning, (B) general, (C) ground-snatching, (D) trunk/ branch-probing, (E) leaf and twig/branch-gleaning/probing, (F) leaf and twig/branch-gleaning and (G) trunk-gleaning niches. Two or more coexisting species with the same foraging niche differed in their bill types. Those vangids that exploited similar resources segregated in their bill types, geographic ranges and/or foraging niches, presumably to avoid severe competition. Several vangid species partially occupied the ecological niche that would be filled by woodpeckers elsewhere.     

Shell shape and habitat use in the North‐west Pacific land snail Mandarina polita from Hahajima,Ogasawara: current adaptation or ghost of species past?

The endemic land snail genus Mandarina of the Ogasawara Islands provides an excellent model system to investigate adaptive radiation. Previously, it has been shown that coexisting species of the islands segregate by microhabitat, so that they are either predominantly found on the ground in relatively wet and sheltered sites, dry and exposed sites, or else are arboreal. Moreover, shell morphology correlates with microhabitat, so that species in wet and sheltered sites tend to have high-spired shells with a high aperture, and those in dry and exposed sites tend to have relatively low-spired shells with a wide aperture. We have now found that on Hahajima, Mandarina polita have variable shell morphology, and there is a correlation between morphology and the depth of leaf litter, as well as the presence/absence of other terrestrial species. Specifically, when high-spired terrestrial Mandarina ponderosa is present, M. polita tend to be low-spired and have a large aperture, indicative of character displacement. When M. ponderosa is absent, the shell shape of M. polita is much more variable, the overall spire is higher, individuals are found in deeper litter, and there is a strong correlation between litter depth and spire height. We argue that these patterns are due to local adaptation, but it remains possible that they are an artefact due to the 'ghost of species past'.  © 2007 The Linnean Society of London, Biological Journal of the Linnean Society , 2007, 91 , 149–159.     

Gene flow of Acanthaster planci (L.) in relation to ocean currents revealed by microsatellite analysis

Population outbreaks of the coral-eating starfish, Acanthaster planci , are hypothesized to spread to many localities in the Indo-Pacific Ocean through dispersal of planktonic larvae. To elucidate the gene flow of A. planci across the Indo-Pacific in relation to ocean currents and to test the larval dispersal hypothesis, the genetic structure among 23 samples over the Indo-Pacific was analysed using seven highly polymorphic microsatellite loci. The F -statistics and genetic admixture analysis detected genetically distinct groups in accordance with ocean current systems, that is, the Southeast African group (Kenya and Mayotte), the Northwestern Pacific group (the Philippines and Japan), Palau, the North Central Pacific group (Majuro and Pohnpei), the Great Barrier Reef, Fiji, and French Polynesia, with a large genetic break between the Indian and Pacific Oceans. A pattern of significant isolation by distance was observed among all samples ( P =  0.001, r  = 0.88, n  = 253, Mantel test), indicating restricted gene flow among the samples in accordance with geographical distances. The data also indicated strong gene flow within the Southeast African, Northwestern Pacific, and Great Barrier Reef groups. These results suggest that the western boundary currents have strong influence on gene flow of this species and may trigger secondary outbreaks.     

Seashore in the mountain: limestone‐associated land snail fauna on the oceanic Hahajima Island (Ogasawara Islands,Western Pacific)

Because land snails inhabiting the seashore are most likely to be carried by ocean currents or by attaching to seabirds, land snail fauna on oceanic islands include species derived from the mainland ancestors inhabiting the seashore. If habitat use of the island descendants is constrained by the ecology of the mainland ancestor, the island species that moved from the coastal habitat to the inland habitat may still be restricted to relatively exposed microhabitats with high pH, calcium carbonate‐rich substrates, and poor litter cover. We tested this hypothesis by investigating the association between environmental conditions and species diversity of seashore‐derived species of the endemic land snails on the oceanic Hahajima Island (Ogasawara Islands). Seashore‐derived species showed higher species richness on limestone outcrops than non‐limestone areas, whereas the other species showed no significant increase in species richness in limestone outcrops. There was a higher proportion of seashore‐derived species on the limestone ridges than on the soil of dolines, even in the limestone area. Accordingly, the species derived from the seashore of the mainland are restricted to microhabitats with poor vegetation cover, poor litter cover, high pH, and calcium carbonate‐rich substrates, which supports the hypothesis that the inland species on an island derived from the mainland seashore still prefer environments similar to the seashore. In addition, the seashore‐derived species on the limestone outcrop include cave‐dwellers lacking functional eyes. This suggests that the probability of colonizing a cave environment is restricted to seashore‐derived species. The findings obtained in the present study suggest that habitat use of the ancestral lineages can constrain habitat use of the descendants, even in the oceanic islands with depauperate fauna. This bias in the species composition on the limestone outcrop constrains lineages that can colonize and adapt to the inside of caves, and therefore, habitat use of the ancestral lineages affects the ability of descendant lineages to colonize novel habitats. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 102 , 686–693.     

Nutritional and Hormonal Requirements for the Growth of Vigna sinensis Callus in vitro

Nutritional and hormonal requirements for in vitro growth of callus tissue of Vigna sinensis Endl. were studied. Callus was formed on hypocotyl and root sections, when they were cultured on Linsmaier and Skoog's basal medium solidified with 10 g/1 agar and supplemented with only 0.5 mg/12,4-D or 2 mg/1 IAA. Further addition of 0.2 mg/1 kinetin and 1 g/l yeast extract resulted in more active callus formation. For unlimited vigorous growth of subcultured callus which was originally isolated from root sections, yeast extract was indispensable besides 2,4-D and kinetin. Such growth-promoting activity was observed also in malt extract and Ebios (dried cell powder of brewery yeast). Of known compounds tested, nicotinic acid, nicotinamide., methyl nicotinate and NAD were promotive to the growth of the callus, although much less effective than yeast extract. Other pyridine derivatives, vitamins and amino acids tested were ineffective or slightly effective. Sucrose was the most suitable carbon source. Fructose, glucose and maltose also supported the growth. Kinetin stimulated cell proliferation of the callus and cell differentiation to tracheary element.