Responses of a fringing Cyperus papyrus L. swamp to changes in water level

Over a 9-year period (1993–2001), the land-water width of a papyrus fringe on the southern shore of Lake Naivasha, Kenya, varied between 40 and 60 m. Increases in width via rhizome spreading into open water followed the 1997/1998 El Niño flood when water depths rose by about 2 m. Germination of papyrus seeds also responded to water depth with a mean ± S.E. rate in experiments of 23 ± 6% after 21 days when water level was 5 cm below the sediment surface. No germination occurred when sediment was flooded or allowed to desiccate. Rhizome spreading from floating mats appeared to be favoured by deep water with seedling spread favoured on newly inundated, low-gradient slopes in shallow water. Although natural regenerative capacity was influenced by water depth, the height, density, biomass and chemical content of papyrus were not. Total average biomass along a land-water transect was 6950 ± 860 g m⁻² which was large in relation to nutrient and mineral contents. Culms contained 0.47 ± 0.14% N and 0.06 ± 0.05% P and rhizomes 0.71 ± 0.21% and 0.10 ± 0.06%. Sediment underlying the swamp was aerobic and there were small land-water gradients in the BOD of swamp water and sediment. However, chemical gradients were weak compared with wider papyrus swamps elsewhere. Lake and swamp water mixed in the narrow fringe studied and residence times for organic matter may not have been long enough for organic material to mineralise before entering lake water.     

Exposure to potentially cannibalistic conspecifics induces an increased immune response

1. Within-population infectious disease dynamics depend on multiple factors, including the ability of hosts to mount an effective immune response. These immune responses can be highly plastic, responding to pathogen risk, as well as the ecological context in which pathogens are encountered. 2. High conspecific density can stimulate immune activity, and recent research suggests that predators can cause indirect protective effects in their prey through the induction of increased immune responses. Comparatively little work, however, has investigated whether exposure to potentially cannibalistic conspecifics, representing both increased density and predatory pressures, will have similar effects on immune expression. 3. Using dragonfly larvae, the present study investigated whether exposure to potentially cannibalistic conspecifics altered the melanisation of simulated parasites. 4. Increased levels of melanisation were found in larvae regardless of whether that conspecific had recently engaged in cannibalism or not. Melanisation also increased as conspecific density increased, even if the conspecifics present were small, and therefore unlikely to pose a cannibalism threat. 5. The findings obtained in the present study indicate that conspecific presence is sufficient to affect immune responses in these insects even though they are relatively solitary compared with the phase-polyphenic taxa typically associated with density-dependent prophylaxis. Because melanisation is also important for wound healing, we suggest that the increased melanin response observed with increased conspecific density might act to induce heightened immunity when faced with potentially increased risk of infection, and also facilitate wound healing under threat of predation/cannibalism.     

Comparison of high fibre diets,basal insulin supplements,and flexible insulin treatment for non-insulin dependent (type II) diabetics poorly controlled with sulphonylureas.

OBJECTIVE--To compare high fibre diet, basal insulin supplements and a regimen of insulin four times daily in non-insulin dependent (type II) diabetic patients who were poorly controlled with sulphonylureas. DESIGN--Run in period lasting 2-3 months during which self monitoring of glucose concentration was taught, followed by six months on a high fibre diet, followed by six months'' treatment with insulin in those patients who did not respond to the high fibre diet. SETTING--Teaching hospital diabetic clinics. PATIENTS--33 patients who had had diabetes for at least two years and had haemoglobin A1 concentrations over 10% despite receiving nearly maximum doses of oral hypoglycaemic agents. No absolute indications for treatment with insulin. INTERVENTIONS--During the high fibre diet daily fibre intake was increased by a mean of 16 g (95% confidence interval 12 to 20 g.) Twenty five patients were then started on once daily insulin. After three months 14 patients were started on four injections of insulin daily. ENDPOINT--Control of diabetes (haemoglobin A1 concentration less than or equal to 10% and fasting plasma glucose concentration less than or equal to 6 mmol/l) or completion of six months on insulin treatment. MEASUREMENTS AND MAIN RESULTS-- No change in weight, diet, or concentrations of fasting glucose or haemoglobin A1 occurred during run in period. During high fibre diet there were no changes in haemoglobin A1 concentrations, but mean fasting glucose concentrations rose by 1.7 mmol/l (95% confidence interval 0.9 to 2.5, p less than 0.01). With once daily insulin mean concentrations of fasting plasma glucose fell from 12.6 to 7.6 mmol/l (p less than 0.001) and haemoglobin A1 from 14.6% to 11.2% (p less than 0.001). With insulin four times daily concentrations of haemoglobin A1 fell from 11.5% to 9.6% (p less than 0.02). Lipid concentrations were unchanged by high fibre diet. In patients receiving insulin the mean cholesterol concentrations fell from 7.1 to 6.4 mmol/l (p less than 0.0001), high density lipoprotein concentrations rose from 1.1 to 1.29 mmol/l (p less than 0.01), and triglyceride concentrations fell from 2.67 to 1.86 mmol/l (p less than 0.05). Patients taking insulin gained weight and those taking it four times daily gained an average of 4.2 kg. CONCLUSIONS--High fibre diets worsen control of diabetes in patients who are poorly controlled with oral hypoglycaemic agents. Maximum improvements in control of diabetes were achieved by taking insulin four times daily.     

The impact of <Emphasis Type="Italic">MTHFR</Emphasis> 677C → T risk knowledge on changes in folate intake: findings from the Food4Me study

Background

It is hypothesised that individuals with knowledge of their genetic risk are more likely to make health-promoting dietary and lifestyle changes. The present study aims to test this hypothesis using data from the Food4Me study. This was a 6-month Internet-based randomised controlled trial conducted across seven centres in Europe where individuals received either general healthy eating advice or varying levels of personalised nutrition advice. Participants who received genotype-based personalised advice were informed whether they had the risk (CT/TT) (n?=?178) or non-risk (CC) (n?=?141) alleles of the methylenetetrahydrofolate reductase (MTHFR) gene in relation to cardiovascular health and the importance of a sufficient intake of folate. General linear model analysis was used to assess changes in folate intake between the MTHFR risk, MTHFR non-risk and control groups from baseline to month 6 of the intervention.

Results

There were no differences between the groups for age, gender or BMI. However, there was a significant difference in country distribution between the groups (p?=?0.010). Baseline folate intakes were 412?±?172, 391?±?190 and 410?±?186 μg per 10 MJ for the risk, non-risk and control groups, respectively. There were no significant differences between the three groups in terms of changes in folate intakes from baseline to month 6. Similarly, there were no changes in reported intake of food groups high in folate.

Conclusions

These results suggest that knowledge of MTHFR 677C?→?T genotype did not improve folate intake in participants with the risk variant compared with those with the non-risk variant.

Trial registration

ClinicalTrials.gov NCT01530139

     

The influence of tissue polarity on nematocyte migration in Hydra attenuata

Influences underlying the direction of nematocyte migration in hydra were studied. Nematocytes arise by interstitial cell differentiation in the body column, and then up to 80% migrate into the ectodermal epithelial cells of the tentacles. The migration of these cells, which is clearly apically directed, may be due either to a chemotactic attraction into the hypostome and tentacles, or to a property inherent in the tissue of the body column, such as the regeneration polarity. To distinguish between these two possibilities, the rates of accumulation of ³H-proline-labeled desmoneme and stenotele nematocytes in unlabeled heads (hypostome and tentacles) grafted either basally or apically to the labeled body column were compared. Basally grafted heads, if left in place for an appropriate length of time, reversed the regeneration polarity of the tissue. In all experiments the direction of desmoneme migration was correlated with the direction (apical or basal) of the regeneration polarity of the tissue. Further, the kinetics of polarity reversal were modified by varying the grafting procedure or the environmental conditions. In every case the kinetics of reversal of desmoneme migration also paralleled the kinetics of reversal of tissue polarity. The results suggest that the direction of desmoneme migration is influenced by the regeneration polarity of the tissue. Stenotele migration was largely unaffected by tissue polarity, but behaved as though chemotactically attracted to the head.     

Oriented migration of interstitial cells and nematocytes inHydra attenuata

Summary The migratory properties of hydra cells within the tissue were studied. The extent and direction of cell migration were examined in budding, non-budding, and regenerating animals. Nematocytes and a small number of single big interstitial cells (the multipotent interstitial cells) actively migrate preferentially in an apical direction. Basal migration of these cells occurs only when a bud is present and, in which case, the cells migrate into the developing bud. The regeneration of the hypostome and tentacles does not affect cell migration in either direction, except for apical migration of stenotele nematocytes, which was markedly reduced.This research was supported by National Science Foundation Grant (GB 29284), National Institute of Health Grant (HD 08086-01), and N.I.H. Public Health Service Training Grant (HD 00347).     

Radioautographic studies of the initial site of formation of protein-bound iodine in the rat thyroid gland

1. Predominantly cellular labelling was observed in radioautographs of rat thyroid glands fixed by perfusion from the aorta at intervals between 5 and 55s after [(125)I]iodide administration via the aorta. 2. When perfusion was delayed for 2min, or if immersion fixation was used, the labelling was predominantly over the peripheral portion of the follicular lumen, in agreement with the observations of other investigators. 3. The findings support the concept that the initial site of binding of iodine to protein is intracellular, but the nature of this protein has not been established.