Does nitric oxide play a role in maternal tolerance towards the foetus?

In pregnancy there occurs maternal tolerance to the foetus. Several mechanisms have been proposed to explain this phenomenon. The main immune population in the decidua are macrophages and natural killer cells, but with some "special" suppressor characteristics. There is also a predominant TH2 response. The non classical MCH type I HLA-G is expressed by trophoblasts and can suppress lymphomononuclear cytotoxicity. Other system to avoid the immune system is the expression of indoleamine-2,3-dioxygenase, that suppresses T cell activation by degrading tryptophan. Even though in the placenta there is a high production of nitric oxide, a well-known immune modulator, low attention has been paid to its role in maternal tolerance. There are many data showing that NO affects the IDO, CD95/CD95-L and the balance between TH1/TH2. Maybe NO could interact with several mechanisms at the same time, which could modify the tolerogenic activity depending on the concentration and the presence of other factors in the medium.     

Does the zona pellucida select spermatozoa from the medium with higher fertilizing potential?

The present study was carried out to test whether the zona pellucida selects spermatozoa with higher fertilization potential. Fertilization rates of mouse oocytes after sperm microinjection under the zona pellucida (SMUZ) of zona-bound spermatozoa and of spermatozoa incubated in the absence of oocytes and treated (acid-treated group) or not (control group) with acid Tyrode's solution were compared. SMUZ was performed at 15, 30, 60, and 90 min after the insemination of fresh oocytes required for selecting spermatozoa bound to the zona pellucida. At these times, the percentages of acrosome-reacted spermatozoa (PARS) were evaluated using the chlortetracycline fluorescence method. Fertilization rate in the three groups analysed increased from 25.9% to 47.3% in the control group, from 29.3% to 44.0% in the acid-treated group, and from 19.5% to 40.0% in the zona-bound group from 15 to 90 min after insemination, respectively. The global fertilization potential was significantly lower in the zona-bound group compared to the other two groups. The PARS in the zona-bound group at 15 (11.48 ± 3.02); 30 (16.74 ± 3.71), and 90 (19.68 ± 3.68) min after insemination were significantly (P < 0.05) lower than those found in the acid-treated group (39.26 ± 6.69, 38.20 ± 6.24, and 42.83 ± 5.39, respectively). At 90 min after insemination, the PARS in the zona-bound group was also significantly (P 0.05) lower than the control group (36.72 ± 4.51). No significant correlation between either time and PARS or PARS and fertilization rate was observed. It appears that the zona pellucida does not select from the medium spermatozoa with higher fertilization potential. © 1993 Wiley-Liss, Inc.     

Does bromocriptine play a role in decreasing oxidative stress for early weaned programmed obesity?

Aims

Studies have demonstrated that early weaning can promote metabolic syndrome during adulthood and that obesity increases oxidative stress. Thus, we aimed to evaluate redox status in a pharmacological early weaning rodent model programmed for metabolic syndrome at adulthood.

Main methods

Lactating dams were randomly assigned into 2 groups: the early weaning group (BRO), which was treated intraperitoneally with bromocriptine (1 mg/day) to inhibit prolactin secretion for the last 3 days of lactation, and the control group (C), which received the BRO diluent for the same time period. The offspring were killed at 90 (PN90) and 180 (PN180) days after birth.

Key findings

Early weaning induced greater visceral adiposity and dyslipidemia. At PN90, the BRO offspring showed glucose intolerance with normoinsulinemia and increased plasma and liver superoxide dismutase, and liver glutathione peroxidase activities, which reduced the liver malondialdehyde but not the increased plasma malondialdehyde levels. However, the BRO offspring showed insulin resistance at PN180 and increased plasma glutathione peroxidase, liver superoxide dismutase, and catalase activities. These changes reduced the plasma and liver malondialdehyde levels, which aided in hepatocyte architecture preservation. Additionally, we observed that sirtuin 1 was overexpressed in the BRO group at PN90, but the increased expression was not maintained through PN180, which suggests unfavorable metabolic conditions in the older offspring.

Significance

Despite the observed obesity and glucose homeostasis dysfunction, our data suggest that the early weaning programming induced by bromocriptine can improve the offspring's redox status and may prevent liver damage during adulthood.     

Can the red mangrove provide food,feed and fertilizer?

The red mangrove is one of the principal features of the coastal vegetation throughout tropical America, Mexico, the West Indies, the Bahamas, Bermuda and southern Florida. It is of primary importance as a land retainer and builder. Secondarily, its bark is a source of tannin and yields resins suitable for plywood adhesive. Mangrove wood is heavy and durable. The bark, leaves and shoots furnish various dyes and the bark is an excellent fuel and is much used locally for medicinal purposes. In southern Florida there has been active interest in the value of mangrove leaf meal as cattle feed, the dried and ground leaves have been sold as “Maritime Tea” and prepared in tablet form as a dietary supplement. The leaf meal and the sawdust have been tested as soil conditioners. Despite their high tannin content, red mangrove leaves may warrant investigation as an abundant source of protein.     

Should we feed back research results in the midst of a study?

ABSTRACT: BACKGROUND: This report is an introduction to a series of three research papers that describe the evolution of the approaches taken by the Translating Research in Elder Care (TREC) research team during its first four years to feed back the research findings to study participants. TREC is an observational multi-method health services research project underway in 36 nursing homes in the prairie provinces of Canada. TREC has actively involved decision makers from the sector in all stages from initial planning, through data collection to dissemination activities. However, it was not planned as a fully integrated knowledge translation project. These three papers describe our progress towards fully integrated knowledge translation--with respect to timely and requested feedback processes. The first paper reports on the process and outcomes of creating and evaluating the feedback of research findings to healthcare aides (unregulated health professionals). These aides provide over 80% of the direct care in our sample and actively requested the feedback as a condition of their continued cooperation in the data acquisition process. The second paper describes feedback from nursing home administrators on preliminary research findings (a facility annual report) and evaluation of the reports' utility. The third paper discusses an approach to providing a more in-depth form of feedback (expanded feedback report) at one of the TREC nursing homes. FINDINGS: Survey and interview feedback from healthcare aides is presented in the first paper. Overall, healthcare aides' opinions about presentation of the feedback report and the understand ability, usability, and usefulness of the content were positive. The second paper describes the use of telephone interviews with facility administrators and indicates that the majority of contextual areas (e.g., staff job satisfaction) addressed in facility annual report to be useful, meaningful, and understandable. More than one-half of the administrators would have liked to have received information on additional areas. The third paper explores how a case study that examined how involvement with the TREC study influenced management and staff at one of the TREC nursing homes. The importance of understanding organizational routines and the impact of corporate restructuring were key themes emerging from the case study. In addition, the Director of Care suggested changes to the structure and format of the feedback report that would have improved its usefulness. CONCLUSIONS: We believe that these findings will inform others undertaking integrated knowledge translation activities and will encourage others to become more engaged in feedback processes.     

Does a polyphagous caterpillar have the same gut microbiota when feeding on different species of food plants?

We used classical culture techniques to explore gut bacteria and changes associated with dietary change in the highly polyphagous, tropical caterpillar Automeris zugana (Saturniidae). Fifty-five third instar wild-caught sibs feeding on Annona purpurea (Annonaceae) in the Area de Conservación Guanacaste (ACG) in northwestern Costa Rica were divided into eight groups. Each of seven groups was reared to the ultimate instar on another species of food plant normally used by A. zugana. Some pupae were also analyzed for the presence of bacteria. Aerobic bacterial cultures were obtained from all 33 caterpillar guts and the eight pupae inventoried. There was no clear pattern in species composition of cultivated bacteria among the eight diets, and each caterpillar on a given food plant carried only a small fraction of the total set of species isolated from the set of caterpillars feeding on that food plant. Taken as a whole, the larvae and pupae contained 22 species of cultivable bacteria in 12 genera. Enterobacter, present in 81.8% of the samples, was the genus most frequently isolated from the caterpillars, followed by Micrococcus and Bacillus. Bacillus thuringiensis was isolated from 30.3% of the dissected caterpillars, but found in caterpillars feeding on only half of the species of food plants.     

Does the effect of pelleting depend on the wheat sample when fed to chickens?

Experimental comparisons of the nutritional value of different wheat cultivars commonly use feeds in meal form even though the large-scale broiler producers use steam pelleted feeds. The aim of this experiment was to examine the effect of steam pelleting on the performance, dietary N-corrected apparent metabolisable energy (AMEn), total tract dry matter retention (DMR), nitrogen retention (NR) and fat digestibility (FD) coefficients, and digestive tract development of broilers fed four different wheat samples in complete diets. Four European wheat samples, with different chemical composition and endosperm characteristics, were used in a broiler experiment. The wheat samples were milled through a 5 mm screen and four basal feeds containing 670 g/kg of each selected wheat sample were mixed. The basal feeds were then split into two batches and one of them was steam pelleted resulting in eight experimental diets. Each diet was fed ad libitum to eight pens of two male Ross 308 broilers from 10 to 24 days of age. Feeding pelleted diets improved (P<0.001) feed intake and weight gain, and daily water intake of the birds. Pelleting also improved dietary AMEn and FD (P<0.001) and DMR (P<0.05). An interaction (P<0.05) was observed between wheat samples and steam pelleting for NR. Steam pelleting improved (P<0.05) NR in the wheat sample with high starch and protein and hard endosperm but not in the rest of the wheat samples. Similar interactions (P<0.05) were also observed between wheat sample and steam pelleting for gain to feed (G : F) and water to feed (W : F) ratios. Pelleting improved G : F ratio the greatest in the wheat sample with high starch and protein and hard endosperm. Feeding the same wheat sample also decreased (P<0.05) W : F but only in the mash diets. Regardless of the wheat sample the values of dietary AMEn did not differ (P>0.05). Feeding different wheat types and pelleting did not (P>0.05) change the development of the gastrointestinal tract of the birds. The study showed that there were differences between four wheat samples when they were fed in pelleted complete feed, but no differences were observed when fed in mash form complete diets. Research on the interaction between pelleting and wheat chemical and quality characteristics is warranted.     

Does sex-ratio selection influence nest-site choice in a reptile with temperature-dependent sex determination?

Evolutionary theory predicts that dioecious species should produce a balanced primary sex ratio maintained by frequency-dependent selection. Organisms with environmental sex determination, however, are vulnerable to maladaptive sex ratios, because environmental conditions vary spatio-temporally. For reptiles with temperature-dependent sex determination, nest-site choice is a behavioural maternal effect that could respond to sex-ratio selection, as mothers could adjust offspring sex ratios by choosing nest sites that will have particular thermal properties. This theoretical prediction has generated decades of empirical research, yet convincing evidence that sex-ratio selection is influencing nesting behaviours remains absent. Here, we provide the first experimental evidence from nature that sex-ratio selection, rather than only viability selection, is probably an important component of nest-site choice in a reptile with temperature-dependent sex determination. We compare painted turtle (Chrysemys picta) neonates from maternally selected nest sites with those from randomly selected nest sites, observing no substantive difference in hatching success or survival, but finding a profound difference in offspring sex ratio in the direction expected based on historical records. Additionally, we leverage long-term data to reconstruct our sex ratio results had the experiment been repeated in multiple years. As predicted by theory, our results suggest that sex-ratio selection has shaped nesting behaviour in ways likely to enhance maternal fitness.     

Does random X-inactivation in mammals reflect a random choice between two X chromosomes?

Inactivation of the maternal or paternal X chromosome in a mammalian embryonic XX cell is believed to involve random choice between the two X's. We propose two alternative models. One suggests that choice is not random, while the other is consistent with random choice, but not one between two X's.     

Does myoglobin protect Trypanosoma cruzi from the antiparasitic effects of nitric oxide?

The hemoflagellate protozoan parasite Trypanosoma cruzi is the causative agent of Chagas disease, a progressive fatal cardiomyopathy widespread in South and Central America. Here, we postulate that the preferential colonization of cardiomyocytes by T. cruzi may reflect the role of myoglobin (Mb) as a nitric oxide (NO) scavenger, protecting the parasite from the trypanocidal effects of NO. The proposal of this novel function of Mb is based on knowledge that ferrous oxygenated Mb reacts rapidly and irreversibly with NO yielding nitrate and ferric oxidized Mb, which is reduced back to the physiologically active form by an intracellular reductase. The postulated protective role of Mb on the viability of T. cruzi is reminiscent of that postulated for hemoglobin in protecting intraerythrocytic Plasmodia from the parasiticidal effect of NO.