Neuroendocrine regulation of ovarian maturation in the Indian white prawn Penaeus indicus H. Milne Edwards

Neuroendocrine Regulation of ovarian maturation in the Indian white prawn Penaeus indicus H. Milne Edwards. Aquaculture, 98: 381-393. The control and regulation of ovarian maturation by neurosecretory elements in the eyestalk, brain and thoracic ganglia of Penaeus indicus have been examined. In the X-organ complex of the eyestalk, secretions from type A and B cells are apparently involved in inhibiting ovarian maturation, while in the brain and thoracic ganglia, secretions from type GN, A and B ce!ls had a stimulatory effect on the ovary. The pyriform C cells were not involved with ovarian maturation. Both unilateral and bilateral eyestalk ablation resulted in precocious maturation of the ovary. The histology of the remaining eyestalk in unilaterally ablated animals revealed that all the NSCs in the X-organs were in a suppressed state and the sinus gland was devoid of granular aggregations. Abnormal behaviour was noticed in bilaterally ablated prawns and strangely few animals moulted with developing ovaries. Due to the synchronous occurrence of moulting and reproductive activities the probability of both gonad and moult inhibiting hormones being the same is discussed. In addition the relationship between gonadal maturation and the moult cycle has also been studied

Effect of androgenic gland ablation on sexual characters of the male Indian white prawn Penaeus indicus H. Milne Edwards.

Bilateral and rectomy was carried out in penaeid prawns.Results indicated that in the absence of androgenic glallds male secondary sexual characters once lost cannot be regenerated. Andrectomy also appeared to block spermatogonial differentiation

Fluctuations in Ca, Mg and P levels in the hemolymph, muscle, midgut gland and exoskeleton during the moult cycle of the Indian white prawn, Penaeus indicus (Decapoda: Penaeidae)

Fluctuations of Ca, Mg and P in the hemolymph, midgut gland, muscle and exoskeleton of the penaeid prawn Penaeus indicus during different stages of the moulting cycle have been investigated. 2. Haemolymph, midgut gland and muscle showed a high content of Ca during late premoult stages and low content in late postmoult and intermoult stages. In exoskeletal tissue the Ca level was high in intermoult and early premoult stages and the lowest level was recorded in the early postmoult stage. Magnesium showed an almost similar trend to that of Ca. Phosphorus content did not show noticeable changes in haemolymph and muscle during moult cycle; in exoskeleton, higher levels were recorded in last premoult and early postmoult stages. 3. The quantitative distribution of Ca, Mg and P in different parts of the exoskeleton was mapped

Biochemical changes in different tissues during yolk synthesis in marine prawn Penaeus indicus H. Milne Edwards

Biochemical changes taking place in ovary, hepatopancreas, muscle and haemolymph of P. indicus during ovarian maturation have been studied and quantified. The trends in the fluctuation of metabolites indicate that in ovary th~re is considerable accumulation of protein, lipid, cholester9l and carotenoids but loss of moisture and nucleic acids. Translocation of these metabolites takes place from the chief synthetic and storage organ, hepatopancreas, via haemolymph. During the initial stages of yolk synthesis, ovary is autosynthetic as indicated by high RNA values and RNNprotein ratio. Subsequently the mode of yolk formation shifts to heterosynthesis mainly through the uptake of lipid from hepatopancreas. RNNDNA ratio has been found to be useful as an index of ovarian growth

Studies on moult staging, moulting duration and moulting behaviour in Indian White shrimp Penaeus indicus Milne Edwards (Decapoda: Penaeidae)

Characterisation and classification of complete moult cycle of Penaeus indicus have been worked out on the basis of setal development Seotogenic moults taging was found to be a rapid and simple technique. Since excision of appendage is not required, this technique is non-destuctive and permits repetitive moult staging of an individual shrimp

Vitellogenesis in the Indian white prawn Penaeus indicus (Crustacea: Decapoda: Penaeidae)

The process of vitellogenesis in Penaeus indicus has been investigated using histological, histochemical, and electron microscopic methods. Based on the changes evident in the cytoplasm and nucleus, five vitellogenic phases are recognized. Histochemical studies revealed the yolk to be a glycolipoProtein complex, with proteins being the first to be associated with the yolk complex, followed by carbohydrates and finally lipids. Yolk formation apparently takes place by the selective deposition and sequestration of organic material from within (autosynthesis) and without (heterosynthesis)

Decaying neutralino dark matter in anomalous U(1)HU(1)_H models

In supersymmetric models extended with an anomalous $U(1)_H$ different R-parity violating couplings can yield an unstable neutralino. We show that in this context astrophysical and cosmological constraints on neutralino decaying dark matter forbid bilinear R-parity breaking neutralino decays and lead to a class of purely trilinear R-parity violating scenarios in which the neutralino is stable on cosmological scales. We have found that among the resulting models some of them become suitable to explain the observed anomalies in cosmic-ray electron/positron fluxes.Comment: 19 pages, 3 figures. References added, typos corrected, accepted version in Phys Rev

Laboratory simulations show diabatic heating drives cumulus-cloud evolution and entrainment

Clouds are the largest source of uncertainty in climate science, and remain a weak link in modeling tropical circulation. A major challenge is to establish connections between particulate microphysics and macroscale turbulent dynamics in cumulus clouds. Here we address the issue from the latter standpoint. First we show how to create bench-scale flows that reproduce a variety of cumulus-cloud forms (including two genera and three species), and track complete cloud life cycles—e.g., from a “cauliflower” congestus to a dissipating fractus. The flow model used is a transient plume with volumetric diabatic heating scaled dynamically to simulate latent-heat release from phase changes in clouds. Laser-based diagnostics of steady plumes reveal Riehl–Malkus type protected cores. They also show that, unlike the constancy implied by early self-similar plume models, the diabatic heating raises the Taylor entrainment coefficient just above cloud base, depressing it at higher levels. This behavior is consistent with cloud-dilution rates found in recent numerical simulations of steady deep convection, and with aircraft-based observations of homogeneous mixing in clouds. In-cloud diabatic heating thus emerges as the key driver in cloud development, and could well provide a major link between microphysics and cloud-scale dynamics

Large Non-perturbative Effects of Small \Delta m^2_{21}/\Delta m^2_{31} and \sin \theta_{13} on Neutrino Oscillation and CP Violation in Matter

In the framework of three generations, we consider the CP violation in neutrino oscillation with matter effects. At first, we show that the non-perturbative effects of two small parameters, \Delta m_{21}^2/\Delta m_{31}^2 and \sin \theta_{13}, become more than 50% in certain ranges of energy and baseline length. This means that the non-perturbative effects should be considered in detailed analysis in the long baseline experiments. Next, we propose a method to include these effects in approximate formulas for oscillation probabilities. Assuming the two natural conditions, \theta_{23}=45^\circ and the fact that the matter density is symmetric, a set of approximate formulas, which involve the non-perturbative effects, has been derived in all channels.Comment: 25 pages, 4 figures, version to appear in JHE