Insulin-Like Signalling Influences the Coordination of Larval Hemocyte Number with Body Size in Drosophila melanogaster

Blood cells, known as hemocytes in invertebrates, play important and conserved roles in immunity, wound healing and tissue remodelling. The control of hemocyte number is therefore critical to ensure these functions are not compromised, and studies using Drosophila melanogaster are proving useful for understanding how this occurs. Recently, the embryonic patterning gene, torso-like (tsl), was identified as being required both for normal hemocyte development and for providing immunity against certain pathogens. Here, we report that Tsl is required specifically during the larval phase of hematopoiesis, and that tsl mutant larvae likely have reduced hemocyte numbers due to a reduced larval growth rate and compromised insulin signaling. Consistent with this, we find that impairing insulin-mediated growth, either by nutrient deprivation or genetically, results in fewer hemocytes. This is likely the result of impaired insulin-like signaling in the hemocytes themselves, since modulation of Insulin-like Receptor (InR) activity specifically in hemocytes causes concomitant changes to their population size in developing larvae. Taken together, our work reveals the strong relationship that exists between body size and hemocyte number, and suggests that insulin-like signaling contributes to, but is not solely responsible for, keeping these tightly aligned during larval development.

Correlations Between Red Blood Cells' Variables, Cardio-Pysiological and Anthropological Variables in Young Athletes

AIM

The aim of this study was to determine and analyse the relations between anthropometric parameters, red blood cells' (RBC) variables and cardio-physiological parameters in healthy and physically active children and adolescents.

MATERIAL AND METHODS

In this study 625 subjects, (410 males and 215 females; age span 8 to 18 years) underwent body composition analysis (Matiegka method), blood analysis and ergometry testing (Bruce protocol).

RESULTS

In both groups, body height and weight were positively correlated with RBC variables. In female group almost all correlations between RBC variables and body components were insignificant. In boys all absolute body mass components showed positive correlations with RBC variables with notice that body fat mass had lowest correlation coefficient. Body fat percent (BF %) did not show any correlation with RBC variables in both gender groups. In boys BF % had moderate negative correlation with aerobic performance: exercise time (ET) and VO2max (rs = -0.41 and rs = -0.39). Lean body components showed weak positive correlations with ET and VO2max. RBC count did not show significant correlation with any cardio-physiological parameter in both groups. Haematocrit and haemoglobin showed weak positive correlations with VO2 max and general endurance (exercise time). In girls all correlations between cardio-physiological and RBC variables were insignificant. The relationship between all body components and all cardio-physiological variables in girls were statistically insignificant.

CONCLUSIONS

Our findings revealed that there are some expected positive correlations between lean body mass components, aerobic performance and RBC variables in boys, while in girls such relations were not noticed.

Association of serum bilirubin with longevity: Evidence from a retrospective longitudinal study and cross-sectional data

Bilirubin is a potent antioxidant and an important anti-inflammatory factor. Therefore, there has been an increasing focus on serum bilirubin as a negative risk factor of cardiovascular mortality in men and an indicator of improved survival in both sexes, but the direct mechanisms of these links and the causes of sex differences are not well understood. Moreover, the evidence from longitudinal studies on effects of bilirubin on longevity is limited. In this study, we retrospectively analyzed two groups of older adults to explore age-dependent changes in serum bilirubin levels and their associations with long-term survival in both sexes. Longitudinal data from 142 individuals (68 men and 74 women) aged 45 to 70 years were compared with cross-sectional data from 225 individuals (113 men and 112 women). The latter group was divided into four categories of survival, i.e. 53, 63, 68, and 76+ based on data on lifespan. ANOVA, t-test, and regression analysis were run. The analysis of the longitudinal data showed an increase in serum total bilirubin levels in men (0.3038e0.093x, R2 = 0.667) and women (0.1838e0.0187x, R2 = 0.950), while the analysis of cross-sectional data revealed a U-shaped pattern of age-related changes in men (0.001x2 - 0.1263x + 4.4524, R2 = 0.999) but an inverted U-shaped pattern in women (0.0006x2 + 0.072x - 1.6924, R2 = 0.195). On balance, these results suggest that elevated but normal bilirubin levels might confer a survival advantage in older men but not women. Alternatively, the positive relationship between serum total bilirubin and lifespan was not causal but coincidental. Further studies are needed to elucidate the direct mechanisms of the association between serum bilirubin levels and longevity in elderly people of both sexes.