Growth, diet and condition of goldsinny on the west coast of Scotland

A study of seasonal, locational and sexual variations of growth, diet, somatic condition ( K _s), gonadosomatic condition (GSI) and hepatosomatic condition (HSI), of the goldsinny wrasse, Ctenolabrus rupestris , was made on specimens taken from three areas (Millport, Oban and Luing) of the west coast of Scotland from May 1992 to June 1993. Capture throughout the year was by either baited creel or by anaesthetics applied underwater. Male goldsinny of age 1 year and older ranged in total length from 67-155 mm, total weight 3.8-58.8 g, and had a maximum age of 14+ years. Females of 1 year and older ranged in total length from 59-159 mm, total weight 2.4-65.4 g and had a maximum age of 20+ years. Juvenile (0 +) goldsinny were mostly of indeterminate sex, ranged in total length from 16-57 mm, and total weight 0.08-1.97 g. Female growth was slower than that of males for all three locations; growth of male and female goldsinny from Millport was slower than the respective sexes at the other two locations. Length-weight relationships varied with age and location. There were differences in K _s, GSI, HSI and dietary trends associated with variation in season, sex and location. The implications of this variation are discussed in relation to the management of a sustainable goldsinny fishery.     

Late‐life time‐restricted feeding and exercise differentially alter healthspan in obesity

Aging and obesity increase multimorbidity and disability risk, and determining interventions for reversing healthspan decline is a critical public health priority. Exercise and time‐restricted feeding (TRF) benefit multiple health parameters when initiated in early life, but their efficacy and safety when initiated at older ages are uncertain. Here, we tested the effects of exercise versus TRF in diet‐induced obese, aged mice from 20 to 24 months of age. We characterized healthspan across key domains: body composition, physical, metabolic, and cardiovascular function, activity of daily living (ADL) behavior, and pathology. We demonstrate that both exercise and TRF improved aspects of body composition. Exercise uniquely benefited physical function, and TRF uniquely benefited metabolism, ADL behavior, and circulating indicators of liver pathology. No adverse outcomes were observed in exercised mice, but in contrast, lean mass and cardiovascular maladaptations were observed following TRF. Through a composite index of benefits and risks, we conclude the net healthspan benefits afforded by exercise are more favorable than those of TRF. Extrapolating to obese older adults, exercise is a safe and effective option for healthspan improvement, but additional comprehensive studies are warranted before recommending TRF.     

Nematodirus battus: development of cold hardiness in dormant eggs

Thermistors and an amplified bridge were used to detect supercooling points of Nematodirus battus eggs weighing ca. 1 microgram wet weight. A cooling rate of about 1 C min-1 was achieved with a manually controlled cold stage using the Peltier effect. The supercooling point of eggs fell during chilling at 5 +/- 1 C for up to 8 weeks from -34.48 +/- 0.49 C to -37.17 +/- 0.76 C. Juveniles freed from these eggs were less cold hardy than intact eggs but chilling improved their supercooling to a greater extent from -19.33 +/- 1.38 C to -32.10 +/- 0.68 C. These results were obtained with eggs showing the characteristic hatching response for this species after transfer from chilling at 5 C to higher temperatures (5-37 +/- 1 C). The results indicate eggs of N. battus acclimate to chilling at a time when previous work had established an increase in their trehalose content.     

A factor synthesized by rabbit periosteal fibroblasts stimulates bone resorption and collagenase production by connective tissue cells in vitro

Unstimulated monolayer cultures of confluent rabbit periosteal fibroblasts synthesize a factor that stimulates bone resorption in vitro. Furthermore it stimulates rabbit chondrocytes and mouse osteoblasts to synthesize collagenase. The factor has no effect on dead bone in culture, and its activity on live bone is mediated principally by osteoclasts, since it is 75% inhibited by salmon calcitonin. Characterization of the factor by gel filtration and isoelectric focusing indicates an M_r in the range 15 000–25 000 and a pI corresponding to approx. pH 4.7. These biological and physicochemical properties are similar to those reported for a factor released by peripheral blood monocytes. However, whereas human monocyte factor in both the crude and partially-purified state exhibits interleukin-1 activity, crude and fractionated periosteal fibroblast-conditioned medium does not. This is the first report of a conditioned medium containing a molecule like the monocyte-factor which appears to have no interleukin 1 activity. The factor may be synthesized by a wide range of cell types, and could have an important role in mediating connective tissue degradation during both physiological and pathological resorption.     

Factors influencing the potential mobility and bioavailability of exchangeable ammonium ion in dried lake sediments

Abstract

The effect of drying temperature and oxidation on the level of exchangeable ammonium ion found in sediments has been examined using samples collected from along a polluted creek and from shallow lake bays. The sediments were dried at temperatures between 20°C and 100°C (either in air or under a nitrogen atmosphere), and the ammonium ion content was extracted into 0.1 M KCl prior to analysis using an ion selective electrode. Exposure to air during the drying stage usually resulted in lower ammonium values, while increasing the drying temperature altered the amount of displaceable (i.e. available) ammonium ion extracted, generally in an upward direction. The amount detected (5–25 μ g^?1) varied between sites, and surface sediment values differed from the 10–50 cm core material results. The pH of the extracts varied with the drying temperature used, indicating that the heating process promoted some chemical changes in the test samples. The study has demonstrated that in nutrient level surveys, the analytical data produced can depend greatly on the sample preparation procedure selected. It also indicated the type of changes which could occur when dredged sediments are land dumped.     

Septicaemia in the Neutropenic Patient

A total of 29 cases of septicaemia proved by blood culture in 22 severely neutropenic patients with acute leukaemia or aplastic anaemia have been studied. The recovery rate was 75% in the Gram-positive septicaemias and 60% in the Gram-negative septicaemias in which treatment response could be evaluated. Neutropenia predisposed to septicaemia and its degree seemed to be important. The underlying state of the bone marrow was an important prognostic factor; the neutrophil count at the time of diagnosis and the infecting organism were less important. Gentamicin was the single most useful antibiotic, and the infection was controlled largely with gentamicin and one other antibiotic, most often carbenicillin. Possibly a similar result could have been obtained with gentamicin alone, but since the bacterial flora in a given environment is changeable empirical antibiotic regimens should remain flexible.     

Increasing picocyanobacteria success in shelf waters contributes to long‐term food web degradation

Continental margins are disproportionally important for global primary production, fisheries and CO₂ uptake. However, across the Northeast Atlantic shelves, there has been an ongoing summertime decline of key biota—large diatoms, dinoflagellates and copepods—that traditionally fuel higher tropic levels such as fish, sea birds and marine mammals. Here, we combine multiple time series with in situ process studies to link these declines to summer nutrient stress and increasing proportions of picophytoplankton that can comprise up to 90% of the combined pico‐ and nanophytoplankton biomass in coastal areas. Among the pico‐fraction, it is the cyanobacterium Synechococcus that flourishes when iron and nitrogen resupply to surface waters are diminished. Our field data show how traits beyond small size give Synechococcus a competitive edge over pico‐ and nanoeukaryotes. Key is their ability to grow at low irradiances near the nutricline, which is aided by their superior light‐harvesting system and high affinity to iron. However, minute size and lack of essential biomolecules (e.g. omega‐3 polyunsaturated fatty acids and sterols) render Synechococcus poor primary producers to sustain shelf sea food webs efficiently. The combination of earlier spring blooms and lower summer food quantity and quality creates an increasing period of suboptimal feeding conditions for zooplankton at a time of year when their metabolic demand is highest. We suggest that this nutrition‐related mismatch has contributed to the widespread, ~50% decline in summer copepod abundance we observe over the last 60 years. With Synechococcus clades being prominent from the tropics to the Arctic and their abundances increasing worldwide, our study informs projections of future food web dynamics in coastal and shelf areas where droughts and stratification lead to increasing nutrient starvation of surface waters.