B-chromosomes and male-biased sex ratio with paternal inheritance in the fairy shrimp Branchipus schaefferi (Crustacea, Anostraca)

This study reports on male-biased sex ratios in west Mediterranean populations of the freshwater anostracan Branchipus schaefferi (Crustacea, Anostraca, Branchipodidae), in contrast to populations elsewhere. Crossing experiments over several generations indicate a clear paternal inheritance of the trait, possibly with a dosage effect. Various mechanisms which may underlie this phenomenon are discussed, the most plausible being the presence of one or more supernumerary ('B') chromosomes--as evidenced by karyological observations--interfering with sex determination and probably having an accumulation mechanism in male individuals.     

Calcium accumulation and regulation in Daphnia magna: Links with feeding, growth and reproduction

Calcium is involved in a wide variety of biological processes and has an important structural role in crustaceans. The present study aimed at exploring the possible link between Ca body concentrations and the ingestion rate and the role of soft tissue vs. total tissue Ca accumulation in Daphnia magna. D. magna was cultured for 21 days at different water Ca concentrations ranging from 3.4 to 32.5 mg/L. Every week Ca body concentrations (soft and total tissues), ingestion rate, growth, survival and reproduction were measured. Daily, algal food that was not deficient in Ca was supplied. Ca in the soft tissues represented 8 to 26% of the total Ca body concentrations. The ratio Ca in soft tissue/Ca in total tissue was generally not influenced by the Ca exposure concentration but decreased with time, i.e., age (from an average of 0.24 at day 7 to 0.09 at day 21). During week 1, a 54% decrease in Ca body concentrations was observed in daphnids exposed in medium with 3.4 mg/L Ca compared to those exposed to 32.5 mg/L. The concurrent decrease in ingestion rate was 14%. No significant differences among Ca treatments were observed during week 2 for ingestion rate and week 3 for calcium body concentrations. Also, no effects on growth and reproduction were observed, although these were expected at the lowest Ca concentration tested. It is hypothesised that Ca absorption from food in combination with an increased ingestion rate is used to maintain Ca homeostasis under Ca limiting conditions.     

Current progress in use of adipose derived stem cells in peripheral nerve regeneration

Unlike central nervous system neurons; those in the peripheral nervous system have the potential for full regeneration after injury. Following injury, recovery is controlled by schwann cells which replicate and modulate the subsequent immune response. The level of nerve recovery is strongly linked to the severity of the initial injury despite the significant advancements in imaging and surgical techniques. Multiple experimental model shave been used with varying successes to augment the natural regenerative processes which occur following nerve injury. Stem cell therapy in peripheral nerve injury may be an important future intervention to improve the best attainable clinical results. In particular adipose derived stem cells(ADSCs) are multipotent mesenchymal stem cells similar to bone marrow derived stem cells, which are thought to have neurotrophic properties and the ability to differentiate into multiple lineages. They are ubiquitous within adipose tissue; they can form many structures resembling the mature adult peripheral nervous system. Following early in vitro work; multiple small and large animal in vivo models have been used in conjunction with conduits, autografts and allografts to successfully bridge the peripheral nerve gap. Some of the ADSC related neuroprotective and regenerative properties have been elucidated however much work remains before a model can be used successfully in human peripheral nerve injury(PNI). This review aims to provide a detailed overview of progress made in the use of ADSC in PNI, with discussion on the role of a tissue engineered approach for PNI repair.     

Uncertainties in the Environmental Risk Assessment of Metals

As life has evolved in the presence of metals, the assessment of the potential adverse effects of metals on ecosystems requires a different approach than those presently used for man-made organic substances. This article provides a brief review of applications and limitations of current techniques and presents, based on recent research results, suggestions for improving the scientific relevance and accuracy of environmental risk assessments of metals. The importance of the following factors responsible for major uncertainties in current environmental risk assessments of metals are discussed: factors affecting metal bioavailability and toxicity, the potential importance of deficiency effects (for essential metals), and field extrapolation of laboratory toxicity data. Possible (regulatory) consequences of inaccurately assessing the natural background concentrations of metals and acclimatization/adaptation potential of laboratory organisms and resident communities are illustrated using examples of recent research, hypothesis development, and a probabilistic environmental risk assessment.     

Metallothionein and cellular energy allocation in the estuarine mysid shrimp Neomysis integer exposed to cadmium at different salinities

In the present study the induction of metallothioneins (MTs) and effects on the cellular energy allocation (CEA) in euryhaline crustacean Neomysis integer exposed to Cd at different salinities were studied. N. integer was exposed to the same sub-lethal concentration of free cadmium ion (1/5 of the cadmium activity of the reported 96 h LC₅₀ value) in hypo-osmotic (7.2 μg Cd/L at 5 psu), isosmotic (23.0 μg Cd/L at 16 psu) and hyper-osmotic media (38.1 μg Cd/L at 25 psu) for 7 days. By using the free Cd concentration as the basis for conducting the exposures, the effect of salinity on cadmium speciation was eliminated and therefore the true effect of salinity as an abiotic factor on the MT induction and CEA could be studied.MT content was quantified by differential pulse voltammetry (DPV); this is the first time that this method is applied to assays with N. integer. No significant differences in MT levels between the control and Cd-exposed groups were observed. The measured MT levels (ranging from 32.3 to 75.7 μg/mg_{(cytosolic protein)}) probably represent the constitutive MT levels responsible for binding essential metals. The differences in MT levels observed at the different salinities indicate a possible relationship between some physiological process (possibly osmoregulation) other than detoxification and MT induction. A decrease in salinity caused an increase in MT level in N. integer, and this was significantly correlated to the CEA values (Spearman correlation coefficient r = − 0.56, p = 0.016). Our results indicate that salinity can change the energy status and MT content of N. integer. These findings should be taken into account when using these biomarkers - and especially MTs - in field studies and environmental monitoring.