The dynactin complex is required for cleavage plane specification in early Caenorhabditis elegans embryos.

BACKGROUND: During metazoan development, cell diversity arises primarily from asymmetric cell divisions which are executed in two phases: segregation of cytoplasmic factors and positioning of the mitotic spindle - and hence the cleavage plane -relative to the axis of segregation. When polarized cells divide, spindle alignment probably occurs through the capture and subsequent shortening of astral microtubules by a site in the cortex. RESULTS: Here, we report that dynactin, the dynein-activator complex, is localized at cortical microtubule attachment sites and is necessary for mitotic spindle alignment in early Caenorhabditis elegans embryos. Using RNA interference techniques, we eliminated expression in early embryos of dnc-1 (the ortholog of the vertebrate gene for p150(Glued)) and dnc-2 (the ortholog of the vertebrate gene for p50/Dynamitin). In both cases, misalignment of mitotic spindles occurred, demonstrating that two components of the dynactin complex, DNC-1 and DNC-2, are necessary to align the spindle. CONCLUSIONS: Dynactin complexes may serve as a tether for dynein at the cortex and allow dynein to produce forces on the astral microtubules required for mitotic spindle alignment.

Completion of cytokinesis in C. elegans requires a brefeldin A-sensitive membrane accumulation at the cleavage furrow apex.

BACKGROUND: The terminal phase of cytokinesis in eukaryotic cells involves breakage of the intercellular canal containing the spindle midzone and resealing of the daughter cells. Recent observations suggest that the spindle midzone is required for this process. In this study, we investigated the possibility that targeted secretion in the vicinity of the spindle midzone is required for the execution of the terminal phase of cytokinesis. RESULTS: We inhibited secretion in early C. elegans embryos by treatment with brefeldin A (BFA). Using 4D recordings of dividing cells, we showed that BFA induced stereotyped failures in the terminal phase of cytokinesis; although the furrow ingressed normally, after a few minutes the furrow completely regressed, even though spindle midzone and midbody microtubules appeared normal. In addition, using an FM1-43 membrane probe, we found that membrane accumulated locally at the apices of the late cleavage furrows that form the persisting intercellular canals between daughter cells. However, in BFA-treated embryos this membrane accumulation did not occur, which possibly accounts for the observed cleavage failures. CONCLUSIONS: We have shown that BFA disrupts the terminal phase of cytokinesis in the embryonic blastomeres of C. elegans. We observed that membrane accumulates at the apices of the late cleavage furrow by means of a BFA-sensitive mechanism. We suggest that this local membrane accumulation is necessary for the completion of cytokinesis and speculate that the spindle midzone region of animal cells is functionally equivalent to the phragmoplast of plants and acts to target secretion to the equatorial plane of a cleaving cell.

Importance of parenteral nutrition in patients undergoing hemopoietic stem cell transplantation procedures in the autologous system.

OBJECTIVE: The aim of this study was to assess the frequency of parenteral nutrition and to compare the impact of parenteral and oral feeding on the nutrition and clinical status of adults undergoing autologous hemopoietic stem cell transplantation. METHODS: The study involved 35 patients with neoplasm of the hemopoietic system who underwent hemopoietic cell autotransplantation at the Hematology Clinic (Jagiellonian University, Krakow, Poland). The patients' nutrition status was assessed using body mass index (BMI) values, body mass components, concentration of albumin, and total protein in blood serum. The clinical status evaluation included duration of hematologic reconstruction, concentration of bilirubin, enzyme activity (alanine aminotransferase and aspartate aminotransferase), severity of infections, and duration of hospitalization. RESULTS: Parenteral nutrition was required in 19 patients. Oral feeding was used in 16 patients. Symptoms of malnutrition on the day preceding the introduction of conditioning treatment were recorded only in patients requiring parenteral nutrition (31.6%). In the posttransplantation period, a statistically significant decrease in body mass was observed in both groups, whereas the share of fatty tissue in total body mass was significantly less in patients (men and women) fed parenterally. CONCLUSION: A supply of 25-30 kcal/kg and 1-1.5 g protein/kg/day as an element of parenteral nutrition (where 20%-30% of the energy requirement was covered by fats, 15%-20% by amino acids, and 50%-55% by glucose) helped prevent the development of malnutrition and restore the functions of the hemopoietic system at a level comparable to that for patients fed naturally.

The protein participation in daily diet and nutritional status of medical students in Kraków.

PURPOSE: The assessment of protein participation in daily diet together with anthropometric estimation of nutritional status. MATERIAL AND METHODS: There were examined 150 students of Medical Faculty of Jagiellonian University. BMI and MAMC (Mid Arm Muscle Circumference) were examined in order to estimate the nutritional status. Quality of daily diet was estimated by the analysis of daily nutritional ratio (DNR). RESULTS: Underweight was more often observed among women (14.3% vs 5.8%), and overweight and obesity among men (13.4% vs 5.1%). Too low MAMC value was more often observed in the group of men (25% vs 2.4%). Correct MAMC value was represented by most women (86%) and with one exception they were also correct among female with underweight. Not acceptable diet showed 62.5% of male students and 46.8% of female students representing all BMI ranges. The low protein consumption frequency in every day diet showed 25% students with MAMC <5 percentile. CONCLUSIONS: The confirmed disturbances in nutrition among examined students did not find statistically important reflection in protein nutritional status represented by MAMC value. It may confirm short time of duration of nutritional disturbances (potential shortages--no physical symptoms) and may be connected with the lack of quantity estimation of nutrition.