Characterisation of carapace composition in developing and adult ostracods (Skogsbergia lerneri) and its potential for biomaterials

The protective carapace of Skogsbergia lerneri, a marine ostracod, is scratch-resistant and transparent. The compositional and structural organisation of the carapace that underlies these properties is unknown. In this study, we aimed to quantify and determine the distribution of chemical elements and chitin within the carapace of adult ostracods, as well as at different stages of ostracod development, to gain insight into its composition. Elemental analyses included X-ray absorption near-edge structure, X-ray fluorescence and X-ray diffraction. Nonlinear microscopy and spectral imaging were performed to determine chitin distribution within the carapace. High levels of calcium (20.3%) and substantial levels of magnesium (1.89%) were identified throughout development. Amorphous calcium carbonate (ACC) was detected in carapaces of all developmental stages, with the polymorph, aragonite, identified in A-1 and adult carapaces. Novel chitin-derived second harmonic generation signals (430/5 nm) were detected. Quantification of relative chitin content within the developing and adult carapaces identified negligible differences in chitin content between developmental stages and adult carapaces, except for the lower chitin contribution in A-2 (66.8 ± 7.6%) compared to A-5 (85.5 ± 10%) (p = 0.03). Skogsbergia lerneri carapace calcium carbonate composition was distinct to other myodocopid ostracods. These calcium polymorphs and ACC are described in other biological transparent materials, and with the consistent chitin distribution throughout S. lerneri development, may imply a biological adaptation to preserve carapace physical properties. Realisation of S. lerneri carapace synthesis and structural organisation will enable exploitation to manufacture biomaterials and biomimetics with huge potential in industrial and military applications.

Dielectric properties of porcine cerebrospinal tissues at microwave frequencies:in vivo,in vitroand systematic variation with age

The dielectric properties of pig cerebrospinal tissues were measured in vivo and in vitro, in the frequency range of 50 MHz-20 GHz. The total combined measurement uncertainty was calculated at each frequency point and is reported over representative frequency regions. Comparisons were made for each tissue between the two sets of data and with the literature of the past decade. The in vitro study was extended to include tissue from pigs weighing approximately 10, 50 and 250 kg to re-visit the question of the variation of dielectric properties with age. White matter and spinal chord showed significant variation as function of animal age, no age-related variations were recorded for grey matter.

Reducing age at first calving in N'Dama heifers using groundnut cake as a supplement to grazed natural pasture in The Gambia

N'Dama heifers, initially weighing 129 kg at approximately 30 months of age, were supplemented with 250, 500 or 1000 g/head/day groundnut cake for 3 or 6 months during the dry or dry and wet seasons. Highly significant improvements in rates of liveweight gain and reproductive performance were obtained. Supplementation during the dry season only, approximately trebled the proportion of animals calving within 2 years of the beginning of the trial (6 vs 20%, P < 0.05), while this increase was around eight-fold in the animals that continued to receive supplement during the wet season (6 vs 50%, P < 0.05). Conceptions occurred at an overall mean liveweight of 185 kg, and a "target" liveweight of 200 kg for the first conception of N'Dama heifers is proposed as the basis for husbandry recommendations concerning these animals. It is concluded that such intervention can reduce the usually observed age at first calving of village based N'Dama heifers by 12 months, in a fashion that is both practicable and financially advantageous.