The nutrient content and the release of nutrients from fish food and faeces

The fish food and faeces were fractioned into the differentcomponents of phosphorus and nitrogen. There was a rapid release ofphosphorus from the fish food and faeces and a decrease thereafterwhereas ammonium release was slow at first with the rate increasingwith time. Both temperature and pH affected the release of nutrientsfrom fish food and faeces. The release of phosphorus and nitrogen washigher at higher temperatures. The maximum release of phosphorus wasat pH 4.0 whereas nitrogen release was maximum at neutral (7.0) toalkaline (10.0) media.     

Similar cryptic behaviour during the early juvenile phase of two unrelated reef fishes: Epinephelides armatus and Bodianus frenchii

The juveniles of many reef fishes behave cryptically during critical juvenile stages in their life history and thus the microhabitats they often occupy are not well known. Comprehensive surveys of reef fishes on the temperate mid-west coast of Australia identified that juveniles of the unrelated Epinephelides armatus (Epinephelidae) and Bodianus frenchii (Labridae) < 100 mm total length both exhibit cryptic behaviour by exclusively swimming upside down under cave roofs and ledges. These individuals swam among the sponges and small algae in this microhabitat which would provide refuge from predation and also supply the dietary requirements of these two carnivores. Occupying this microhabitat would also reduce intra-specific competition, as individuals > 150 mm were only observed swimming ventrally oriented to the substrate in caves, under ledges or on open reef. Identifying the nursery habitats of fishery species, such as E. armatus and B. frenchii, is critical for understanding their life histories, but would also inform survey designs aimed at determining recruitment strength or variation.     

Complete genome sequence of Algoriphagus sp. PR1, bacterial prey of a colony-forming choanoflagellate

Bacteria are the primary food source of choanoflagellates, the closest known relatives of animals. Studying signaling interactions between the Gram-negative Bacteroidetes bacterium Algoriphagus sp. PR1 and its predator, the choanoflagellate Salpingoeca rosetta, provides a promising avenue for testing hypotheses regarding the involvement of bacteria in animal evolution. Here we announce the complete genome sequence of Algoriphagus sp. PR1 and initial findings from its annotation.     

To what extent are the dietary compositions of three abundant,co‐occurring labrid species different and related to latitude,habitat, body size and season?

This study demonstrated that the dietary composition of each of three abundant reef-associated labrid species in temperate Western Australia differed significantly with latitude and changed with increasing body size and almost invariably differed among those species when they co-occurred. These results were derived from comparisons and multivariate analyses of volumetric dietary data, obtained from the foregut contents of Coris auricularis, Notolabrus parilus and Ophthalmolepis lineolatus from the Jurien Bay Marine Park (JBMP) and waters off Perth, 250 km to the south. Latitudinal differences in the dietary compositions of each species in exposed reefs typically reflected greater contributions by large crustaceans, bivalve molluscs, echinoids and annelids to the diets in the waters off Perth than in the JBMP, whereas the reverse was true for gastropods and small crustaceans. The diet of each species exhibited similar, but not identical, quantitative changes with increasing body size, with the contributions of small crustaceans declining and those of large crustaceans and echinoids increasing, while that of gastropods underwent little change. Within the JBMP, the dietary compositions of both C. auricularis and N. parilus were similar in exposed and sheltered reefs and the same was true for N. parilus in the sheltered reefs and interspersed areas of seagrass. The latter similarity demonstrated that, in both of those divergent habitat types, N. parilus feeds on prey associated with either the sand or the macrophytes that cover and lie between the reefs. Although the main dietary components of each species were the same, i.e. gastropods, small crustaceans (mainly amphipods and isopods), large crustaceans (particularly penaeids and brachyuran crabs) and echinoids, their contributions varied among those species, which accounts for the significant interspecific differences in diet. Coris auricularis had the most distinct diet, due mainly to an ingestion of greater volumes of small crustaceans, e.g. amphipods and isopods, and lesser volumes of large crustaceans, e.g. brachyuran crabs, which was associated with a relatively narrower mouth and smaller teeth and the absence of prominent canines at the rear of the jaw. The above intra and interspecific differences in dietary composition would reduce, on the south-west coast of Australia, the potential for competition for food among and within these three abundant labrids, each of which belongs to different genera within the Julidine clade.     

Cell differentiation and morphogenesis in the colony-forming choanoflagellate Salpingoeca rosetta

It has been posited that animal development evolved from pre-existing mechanisms for regulating cell differentiation in the single celled and colonial ancestors of animals. Although the progenitors of animals cannot be studied directly, insights into their cell biology may be gleaned from comparisons between animals and their closest living relatives, the choanoflagellates. We report here on the life history, cell differentiation and intercellular interactions in the colony-forming choanoflagellate Salpingoeca rosetta. In response to diverse environmental cues, S. rosetta differentiates into at least five distinct cell types, including three solitary cell types (slow swimmers, fast swimmers, and thecate cells) and two colonial forms (rosettes and chains). Electron microscopy reveals that cells within colonies are held together by a combination of fine intercellular bridges, a shared extracellular matrix, and filopodia. In addition, we have discovered that the carbohydrate-binding protein wheat germ agglutinin specifically stains colonies and the slow swimmers from which they form, showing that molecular differentiation precedes multicellular development. Together, these results help establish S. rosetta as a model system for studying simple multicellularity in choanoflagellates and provide an experimental framework for investigating the origin of animal multicellularity and development.     

Do the maximum sizes,ages and patterns of growth of three reef‐dwelling labrid species at two latitudes differ in a manner conforming to the metabolic theory of ecology?

The size and age data and patterns of growth of three abundant, reef‐dwelling and protogynous labrid species (Coris auricularis, Notolabrus parilus and Ophthalmolepis lineolata) in waters off Perth at c. 32° S and in the warmer waters of the Jurien Bay Marine Park (JBMP) at c. 30° S on the lower west coast of Australia are compared. Using data for the top 10% of values and a randomization procedure, the maximum total length (L_T) and mass of each species and the maximum age of the first two species were estimated to be significantly greater off Perth than in the JBMP (all P < 0·001) and the maximum ages of O. lineolata in the two localities did not differ significantly (P > 0·05). These latitudinal trends, thus, typically conform to those frequently exhibited by fish species and the predictions of the metabolic theory of ecology (MTE). While, in terms of mass, the instantaneous growth rates of each species were similar at both latitudes during early life, they were greater at the higher latitude throughout the remainder and thus much of life, which is broadly consistent with the MTE. When expressed in terms of L_T, however, instantaneous growth rates did not exhibit consistent latitudinal trends across all three species. The above trends with mass, together with those for reproductive variables, demonstrate that a greater amount of energy is directed into somatic growth and gonadal development by each of these species at the higher latitude. The consistency of the direction of the latitudinal trends for maximum body size and age and pattern of growth across all three species implies that each species is responding in a similar manner to differences between the environmental characteristics, such as temperature, at those two latitudes. The individual maximum L_T, mass and age and pattern of growth of O. lineolata at a higher and thus cooler latitude on the eastern Australian coast are consistent with the latitudinal trends exhibited by those characteristics for this species in the two western Australian localities. The implications of using mass rather than length as the indicator variable when comparing the maximum sizes of the three species and the trends exhibited by the instantaneous growth rates of those species at different latitudes are explored. Although growth curves fitted to both the L_T and masses at age for the males of each species lay above those for their females, this would not have influenced the conclusions drawn from common curves for both sexes.     

Monoclonal anti-idiotopic antibodies against myasthenia-inducing anti-acetylcholine receptor monoclonal antibodies. Preponderance of nonparatope-directed antibodies affecting antigen binding

To analyze components of the idiotypic network in experimental autoimmune disease, we produced 17 isogeneic anti-idiotopic monoclonal antibodies (anti-Id) against two experimental autoimmune myasthenia gravis-producing anti-acetylcholine receptor (anti-AChR) monoclonal antibodies. We studied the binding of five of the anti-Id to the anti-AChR monoclonal antibodies bearing the complementary idiotopes (Id-mAb). They bound with Kd values ranging from 0.06 to 0.86 nM, values comparable to those of Id-mAb:AChR complexes (0.26 and 0.34 nM). All of the anti-Id tested moderately inhibited the binding of AChR to Id-mAb, whereas for each anti-Id, AChR either strongly inhibited anti-Id binding or had no effect on anti-Id binding. Hence, the inhibition of Id-mAb:AChR binding by anti-Id was not reciprocal with the inhibition of anti-Id:Id-mAb binding by AChR. For each anti-Id, the relative affinities of anti-Id and AChR for Id-mAb together with the lack of symmetry of inhibition by anti-Id compared to inhibition by AChR indicate that these two "ligands" are not competitive inhibitors. Consequently, anti-Id and AChR do not bind to overlapping sites on the Id-mAb, suggesting that the observed inhibition is mediated allosterically. This may be a common mechanism of anti-Id:Id binding, which would have important implications for the mechanism of anti-Id-induced suppression.     

Location of terbium binding sites on acetylcholine receptor-enriched membranes

Acetylcholine receptor-enriched membranes bind 45 terbium cations per receptor. The Tb(III) X-ray scattering factor changes by as much as 30% over a 50 eV range about the L3 absorption edge. We exploit these changes to modulate the contribution of these ions to the X-ray diffraction pattern of oriented receptor-enriched membranes by varying the incident X-ray energy. Difference Fourier analysis of the meridional diffraction amplitudes at two X-ray energies revealed six localized regions of Tb(III) density across the membrane. Most significant is the finding of 18 Tb(III) ions near the entrance and 11 ions near the exit of the ion channel as well as 4 or 5 Tb(III) ions localized in the channel itself. This evidence strongly suggests the presence of anionic carboxylate side-chains on the channel lining.     

Preparturient changes in plasma concentrations of estrone,estradiol-17β and estradiol-17α in the fetal calf: Effects of dexamethasone infusion

The concentrations of total estrogens in fetal calf plasma were determined during a 6–10 day period immediately before delivery. Comparison was made between levels found in untreated calves and calves infused with dexamethasone at the rate of 0.1, 1.0 and 10 mg/24 hours. In untreated calves the plasma estrone, estradiol-17β and estradiol-17α levels remained relatively constant at 38 ± 7 ng ml^?1 (mean ± SEM n = 3), 46 ± 6 ng ml^?1 and 29 ± 5 ng ml^?1 respectively. Infusion with dexamethasone at 0.1 mg/24 hr (3 calves) and 1.0 mg/24 hr (3 calves) was without dramatic effect on plasma estrogen levels. However, in one fetus infused with 10.0 mg/24 hr the dexamethasone treatment may have caused a transitory rise in the levels of all estrogens examined.