Body shape variation and colour change during growth in a protogynous fish

Protogynous sequential hermaphroditism is very common in marine fish. Despite a large number of studies on various aspects of sequential hermaphroditism in fish, the relationship between body shape and colour during growth in dichromatic species has not been assessed. Using geometric morphometrics, the present study explores the relationship between growth, body shape and colouration in Coris julis (L. 1758), a small protogynous labrid species with distinct colour phases. Results show that body shape change during growth is independent of change in colour phase, a result which can be explained by the biology of the species and by the social control of sex change. Also, during growth the body grows deeper and the head has a steeper profile. It is hypothesized that a deeper body and a steeper profile might have a function in agonistic interactions between terminal phase males and that the marked chromatic difference between colour phases allows the lack of strict interdependence of body shape and colour during growth.

Geographical and morphological variation within and between colour phases inCoris julis(L. 1758), a protogynous marine fish

The possible differences between sexes in patterns of morphological variation in geographical space have been explored only in gonochorist freshwater species. We explored patterns of body shape variation in geographical space in a marine sequential hermaphrodite species, Coris julis (L. 1758), analyzing variation both within and between colour phases, through the use of geometric morphometrics and spatially-explicit statistical analyses. We also tested for the association of body shape with two environmental variables: temperature and chlorophyll a concentration, as obtained from time-series of satellite-derived data. Both colour phases showed a significant morphological variation in geographical space and patterns of variation divergent between phases. Although the morphological variation was qualitatively similar, individuals in the initial colour phase showed a more marked variation than individuals in the terminal phase. Body shape showed a weak but significant correlation with environmental variables, which was more pronounced in primary specimens.

Factors influencing colour production from the sugar medium used for the rapid approximation of bacterial counts in fishery products

Results of the studies carried out to elucidate the factors influencing colour production from the sugar medium used for the rapid approximation of bacterial counts in fishery products are reported. The effect of particle size, trace elements, salt soluble protein and non-protein fractions, rate of multiplication of bacteria, in the medium, surface bacteria and the rate of colour production by individual strains of bacteria were studied. It is observed that the best results are obtained when a sea-water homogenate is used.

Occurrence of a deeper red colour in prawn pulp prepared from iced-prawns

In commerce, great importance is given to the color of the dry prawn pulp in its quality evaluation. The possible correlation between this color factor to the iced or not iced condition of the raw prawn used, is investigated. The study reveals that as the icing period of the raw material increases the color of the finished product proportionately intensifies to a bright red compared to light brownish yellow or orange color of the product from the not iced prawn, and at the same time the other characteristics like flavor and taste deteriorates as the time of icing advances. This finding tends to show that the color factor does not reflect the true quality of prawn pulp. Based on chemical data it is suggested that "browning" due to Maillard reaction may have an important role in this color phenomena.

Colour patterns in Ceylonese freshwater crabs (Potamonidae)

In the present paper some preliminary remarks are made on the colour patterns of all the Potamonidae of Sri Lanka. In the opinion of the author more detailed studies will show that the colour pattern of each species is a useful diagnostic aid even with difficult species like those belonging to the "Ceylonensis" complex (Fernando, 1960). Fernando (1960, 1961) has described the species of Potamonidae. Eight species are known all belonging to the genus Paratelphusa. Only one species has been illustrated in colour so far (Fernando, 1960). Black and white pictures of all the other species except Paratelphusa soror (Zenthner) have been given in Fernando (1961). Paratelphusa soror is illustrated in the present paper.

Some remarks on the colour patterns of east African freshwater crabs

Very few accounts of African potamonids refer to natural colouration, and the author cannot recall any describing colour patterns. The generally undistinguished appearance of these crabs is well illustrated by Rathbun (1921) on the Congo Brachyura which includes collector's notes on a number of potamonid species. This article is based on remarks extracted from a communication sent to Dr. C. H. Fernando in connection with the article "Colour patterns in Ceylonese freshwater crabs (Patomonidae)", Bulletin of the Fisheries Research Station, Ceylon, v. 21.1(1970), pp. 1-4.

Reynolds number influence on turbulent blocking effects of a rigid plane boundary (2nd report, direct numerical simulation using townsend's eddy forcing)

The Reynolds number influence on turbulent blocking effects by a rigid plane boundary is studied using direct numerical simulation (DNS). A new forcing method using 'simple model eddies' (Townsend 1976) for DNS of stationary homogeneous isotropic turbulence is proposed. A force field is obtained in real space by sprinkling many space-filling 'simple model eddies' whose centers are randomly but uniformly distributed in space and whose axes of rotation are random. The method is applied to a shear-free turbulent boundary layer over a rigid plane boundary and the blocking effects are investigated. The results show that stationary homogeneous isotropic turbulence is generated in real space using the present method. By using different model eddies with different sizes and rotation speeds, we could change the turbulence properties such as the integral and micro scales, the turbulent Reynolds number and the isotropy of turbulence. Turbulence intensities near the wall showed good agreements with the previous measurement and the linear analysis based on a rapid distortion theory (RDT). The splat effect (i.e., turbulence intensities of the components parallel to the boundary are amplified) occurs near the boundary and the viscous effect prohibits the splat effect at the quasi steady state at low Reynolds number.

Secondary flow near an undulatory surface induced by wall blocking effect

Prandtl's secondary mean motions of the second kind near an undulating surface were explained in terms of turbulent blocking effect and kinematic boundary conditions at the surface, and its order of magnitude was estimated. Isotropic turbulence is distorted by the undulating surface of wavelength λ and amplitude h with a low slope, so that h « λ. The prime mechanism for generating the mean flow is that the far-field Isotropic turbulence is distorted by the non-local blocking effect of the surface to become anisotropic axisymmetric turbulence near the surface with principal axis that is not aligned with the local curvature of the undulation. Then the local analysis can be applied and the mechanism is similar to the mean flow generation mechanism for homogeneous axisymmetric turbulence over a planer surface, i.e. gradients of the Reynolds stress caused by the turbulent blocking effect generate the mean motions. The results from this simple analysis are consistent with previous exact analysis in which the effects of curvature are strictly taken into account. The results also qualitatively agree with flow visualization over an undulating surface in a mixing-box.

Reynolds number influence on turbulent blocking effects of a rigid plane boundary (3rd report, direct numerical simulation on wall blocking effects for anisotropic turbulence)

The Reynolds number influence on turbulent blocking effects by a rigid plane boundary is studied using direct numerical simulation (DNS). A new forcing method proposed in the second report using Townsend's "simple model eddies" for DNS was extended to generate axisymmetric anisotropic turbulence. A force field is obtained in real space by sprinkling many space-filling "simple model eddies" whose centers are randomly but uniformly distributed in space. The axes of rotation are controlled in this study to generate axisymmetric anisotropic turbulence. The method is applied to a shear-free turbulent boundary layer over a rigid plane boundary and the blocking effects for anisotropic turbulence are investigated. The results show that stationary axisymmetric anisotropic turbulence is generated using the present method. Turbulence intensities near the wall showed good agreements with the rapid distortion theory (RDT) for small t (t ≪ TL), where TL. is the eddy turnover time. The splat effect (i. e. turbulence intensities of the components parallel to the surface are amplified) occurs near the boundary and the viscous effect attenuates the splat effect at the quasi steady state at low Reynolds number as for Isotropic turbulence. Prandtl's secondary flow of the second kind does not occur for low Reynolds number flows, which qualitatively agrees with previous observetion in a mixing-box.

Physical Blocking Neural Tube Closure Affects Radial Intercalation and Neural Crest Midline-directed Migration in Xenopus Dorsal Explants

神经管闭合缺陷(NTDs)是一种严重的先天畸形疾病,在新生儿中有千分之一的发病率.神经管融合前后,多种组织参与形态发生运动.神经管一经融合,神经嵴细胞就会向背侧中线方向产生单极突出并向此方向迁移形成神经管的顶部.与此同时,神经管从腹侧开始发生辐射状切入以实现单层化.在此,我们在非洲爪蟾的移植体中机械阻断神经管的闭合以检测其细胞运动及随后的图式形成.结果显示神经管闭合缺陷的移植体不能形成单层化的神经管,并且神经嵴细胞滞留在侧面区域不能向背侧中线迁移,而对神经前体标记基因的检测显示神经管的背腹图式形成并未受到影响.以上结果表明神经管的融合对于辐射状切入和神经嵴细胞向背侧中线方向的迁移过程是必需的,而对于神经管的沿背腹轴方向的图式形成是非必需的.

Effect of colour on the catch of gill nets

The effect of white, green, blue and yellow coloured drift gill nets on their catch with respect to Scomberomorus guttatus (Schneider), Scomberomorus commerson (Lacepede), Scomberomorus lineolatus (Cuvier), Parastomateus niger (Bloch), Euthynnus ajjinis (Cantor) and sharks Carcharius melanopterus is discussed. White nets were more effective for S. guttatus while the coloured ones caught more of P. niger. Blue had no significant effect for sharks. In the case of S. lineolatus, S. commerson and E. affinis no preference to colour was noted.