The interval shuttle run test for intermittent sport players: evaluation of reliability

The reliability of the interval shuttle run test (ISRT) as a submaximal and maximal field test to measure intermittent endurance capacity was examined. During the ISRT, participants alternately run for 30 seconds and walk for 15 seconds. The running speed is increased from 10 km.h(-1) every 90 seconds until exhaustion. Within a 2-week period, 17 intermittent sport players (i.e., 10 men and 7 women) performed the ISRT twice in a sports hall under well-standardized conditions. Heart rates per speed and total number of runs were assessed as submaximal and maximal performance measures. With the exception of the heart rates at 10.0 km.h(-1) for men and 10.0, 12.0, and 13.5 km.h(-1) for women, zero lay within the 95% confidence interval of the mean differences, indicating that no bias existed between the outcome measures at the 2 test sessions (absolute reliability). The results illustrate that it is important to control for heart rate before the start of the ISRT. Relative reliability was high (intraclass correlation coefficient > or = 0.86). We conclude that the reliability of the ISRT as a submaximal and maximal field test for intermittent sport players is supported by the results.     

Murine p53 inhibits the function but not the formation of SV40 T antigen hexamers and stimulates T antigen RNA helicase activity

We have characterized the effects of p53 on several biochemical activities of simian virus 40 (SV40) large tumor (T) antigen. While p53 induced a strong inhibition of the T antigen DNA helicase activity, surprisingly, its RNA helicase activity was stimulated. This supports the liklihood that the DNA and RNA helicase activities of T antigen reflect discrete functions. p53 did not significantly affect the ATP-dependent conversion of T antigen monomers to hexamers. However, the ability of these hexamers to assemble on a DNA fragment containing the viral origin was impaired by p53. Thus, these results suggest that p53 inhibits the function but not the formation of T antigen multimers. This conclusion was further supported by the observation that the addition of a purified p53:T antigen complex was as inhihitory as free p53 to the DNA helicase activity of free T antigen. Thus our data indicates that the targets of p53 inhibition are the functional units of T antigen, namely the hexamers.     

Reversible dissociation of the plant golgi apparatus by brefeldin A

Summary— The effects of the drug Brefeldin A, shown to block the translocation of proteins between the endoplasmic reticulum and the Golgi apparatus in animal cells, were studied on different plant cell systems. In suspension culture cells and root tissues, the Golgi aparatus was affected by Brefeldin A treatments resulting in distortion and dissociation of the Golgi stacks, coupled with appearance of numerous vesicles in the cytoplasm. This process was reversible. Therefore, Brefeldin A provides a powerful tool with which to study Golgi dynamics and function in plant as well as in animal cells.     

Computer simulations improve university instructional laboratories

Laboratory classes are commonplace and essential in biology departments but can sometimes be cumbersome, unreliable, and a drain on time and resources. As university intakes increase, pressure on budgets and staff time can often lead to reduction in practical class provision. Frequently, the ability to use laboratory equipment, mix solutions, and manipulate test animals are essential learning outcomes, and "wet" laboratory classes are thus appropriate. In others, however, interpretation and manipulation of the data are the primary learning outcomes, and here, computer-based simulations can provide a cheaper, easier, and less time- and labor-intensive alternative. We report the evaluation of two computer-based simulations of practical exercises: the first in chromosome analysis, the second in bioinformatics. Simulations can provide significant time savings to students (by a factor of four in our first case study) without affecting learning, as measured by performance in assessment. Moreover, under certain circumstances, performance can be improved by the use of simulations (by 7% in our second case study). We concluded that the introduction of these simulations can significantly enhance student learning where consideration of the learning outcomes indicates that it might be appropriate. In addition, they can offer significant benefits to teaching staff.     

The crystal structure of a high affinity RNA stem-loop complexed with the bacteriophage MS2 capsid: further challenges in the modeling of ligand-RNA interactions

We have determined the structure to 2.8 A of an RNA aptamer (F5), containing 2'-deoxy-2-aminopurine (2AP) at the -10 position, complexed with MS2 coat protein by soaking the RNA into precrystallised MS2 capsids. The -10 position of the RNA is an important determinant of binding affinity for coat protein. Adenine at this position in other RNA stem-loops makes three hydrogen bonds to protein functional groups. Substituting 2AP for the -10 adenine in the F5 aptamer yields an RNA with the highest yet reported affinity for coat protein. The refined X-ray structure shows that the 2AP base makes an additional hydrogen bond to the protein compared to adenine that is presumably the principal origin of the increased affinity. There are also slight changes in phosphate backbone positions compared to unmodified F5 that probably also contribute to affinity. Such phosphate movements are common in structures of RNAs bound to the MS2 T = 3 protein shell and highlight problems for de novo design of RNA binding ligands.     

An ordered EST catalogue and gene expression profiles of cassava (<Emphasis Type="Italic">Manihot esculenta</Emphasis>) at key growth stages

A cDNA library was constructed from the root tissues of cassava variety Huanan 124 at the root bulking stage. A total of 9,600 cDNA clones from the library were sequenced with single-pass from the 5′-terminus to establish a catalogue of expressed sequence tags (ESTs). Assembly of the resulting EST sequences resulted in 2,878 putative unigenes. Blastn analysis showed that 62.6% of the unigenes matched with known cassava ESTs and the rest had no ‘hits’ against the cassava database in the integrative PlantGDB database. Blastx analysis showed that 1,715 (59.59%) of the unigenes matched with one or more GenBank protein entries and 1,163 (40.41%) had no ‘hits’. A cDNA microarray with 2,878 unigenes was developed and used to analyze gene expression profiling of Huanan 124 at key growth stages including seedling, formation of root system, root bulking, and starch maturity. Array data analysis revealed that (1) the higher ratio of up-regulated ribosome-related genes was accompanied by a high ratio of up-regulated ubiquitin, proteasome-related and protease genes in cassava roots; (2) starch formation and degradation simultaneously occur at the early stages of root development but starch degradation is declined partially due to decrease in UDP-glucose dehydrogenase activity with root maturity; (3) starch may also be synthesized in situ in roots; (4) starch synthesis, translocation, and accumulation are also associated probably with signaling pathways that parallel Wnt, LAM, TCS and ErbB signaling pathways in animals; (5) constitutive expression of stress-responsive genes may be due to the adaptation of cassava to harsh environments during long-term evolution.     

HLA association with nasopharyngeal carcinoma in southern Tunisia

In order to study the association of HLA-A, -B and/or DRB1, DQB1 and the nasopharyngeal carcinoma (NPC), 141 patients affected with NPC were typed for the HLA class I by serology method of microlymphocytotoxicity. Among these patients 101 were genotyped for HLA class II system by the PCR-SSP technique. HLA typing results were compared to those of 116 controls. We found that the HLA-A31 and -A33 antigens were significantly more expressed in patients than in the controls (P = 0.016 and 0.010, respectively) and the HLA-A19 antigen, was significantly more frequent in patients when compared to the controls (P = 0.007). The HLA-DRB1*03 and DRB1*13 alleles were significantly more frequent in patients as compared to the controls. The DRB1*01 allele was expressed with a frequency of 20.69% in the controls whereas it was only detected in 3.96% of the NPC patients. Furthermore, the DQB1*05 allele was expressed at a frequency which was significantly less important in affected patient (P = 0.03), whereas, the DQB1*02 allele was more frequent in patients (P = 0.643 × 10⁻⁴). Thus our study revealed a significant increase of HLA-A31, A33, A19, B16, B53 and DRB1*03, DRB1*13 and DQB1*02 alleles in our patients. These markers could play a predisposing role in the development of NPC. In contrast, a decrease of HLA-B14, -B35 and DRB1*01 and DQB1*05 alleles was found suggesting a likely protective effect.     

Neurons and Neuronal Stem Cells Survive in Glucose-Free Lactate and in High Glucose Cell Culture Medium During Normoxia and Anoxia

Several questions concerning the survival of isolated neurons and neuronal stem and progenitor cells (NPCs) have not been answered in the past: (1) If lactate is discussed as a major physiological substrate of neurons, do neurons and NPCs survive in a glucose-free lactate environment? (2) If elevated levels of glucose are detrimental to neuronal survival during ischemia, do high concentrations of glucose (up to 40 mmol/L) damage neurons and NPCs? (3) Which is the detrimental factor in oxygen glucose deprivation (OGD), lack of oxygen, lack of glucose, or the combination of both? Therefore, in the present study, we exposed rat cortical neurons and NPCs to different concentrations of d-glucose ranging from 0 to 40 mmol/L, or 10 and 20 mmol/L l-lactate under normoxic and anoxic conditions, as well as in OGD. After 24 h, we measured cellular viability by biochemical assays and automated cytochemical morphometry, pH values, bicarbonate, lactate and glucose concentrations in the cell culture media, and caspases activities. We found that (1) neurons and NPCs survived in a glucose-free lactate environment at least up to 24 h, (2) high glucose concentrations >5 mmol/L had no effect on cell viability, and (3) cell viability was reduced in normoxic glucose deprivation to 50% compared to 10 mmol/L glucose, whereas cell viability in OGD did not differ from that in anoxia with lactate which reduced cell viability to 30%. Total caspases activities were increased in the anoxic glucose groups only. Our data indicate that (1) neurons and NPCs can survive with lactate as exclusive metabolic substrate, (2) the viability of isolated neurons and NPCs is not impaired by high glucose concentrations during normoxia or anoxia, and (3) in OGD, low glucose concentrations, but not low oxygen levels are detrimental for neurons and NPCs.