Biochemical aspects of basidiospore maturation in Agaricus bisporus at various temperatures

Phosphatidylethanolamine is the main phospholipid of Agaricus bisporus basidiospores obtained under sterile conditions from young basidiomes with closed partial veils. Storing the basidiospores for five months at room temperature resulted in a complete loss of their germinating capacity. Conversely, storing them at a low temperature increased their germination rate by 15-20%. At both temperature levels, the phosphatidylcholine ratio significantly increased during storage to the level found in mature basidiospores. In addition, a drastic (8-10-fold) decrease in trehalose content occurred after two months of storage at room temperature. The trehalose content decreased only 1.5-fold at low temperatures. The involvement of trehalose and lipids in the retention of spore viability is discussed.     

Radio-chemotherapy in anal cancer: Institutional experience at a large radiation oncology center in Chile

Aim

In this article the aim is to provide a concise narrative review and inform the institutional experience at a referral center in Chile with the use of radio-chemotherapy in anal cancer.

Background

Cancer of the anus and anal canal is mainly a loco-regional disease. For years the standard of care has been concomitant radio-chemotherapy, which permits organ preservation and better local control than alternative surgical procedures.

Materials and methods

A retrospective analysis of 44 patients treated between 2002 and 2010 was performed. Local recurrence, distant recurrence and overall survival were analyzed with the Kaplan–Meier method. Relevant groups where compared with the log-rank test and univariate analysis were done with the Cox proportional hazards model.

Results

Median follow-up of the cohort was 56 months, with a minimum follow-up of at least 24 months. There was a significant difference between clinical stages in disease free survival (log-rank trend p < 0.001), and a significant difference in overall survival (OS) when comparing clinical stages that were grouped in stage I–IIIa and IIIB (log-rank p = 0.001). On univariate analysis, age older than 60, having received full treatment and dose above 45 Gy were all significantly related to OS (p < 0.05). An overall survival of 45% and disease free survival of 45% at 5 years were found in our series.

Conclusions

Our findings show that results at the Instituto de Radiomedicina in Chile are comparable to published literature. Dismal results in stage IIIb cases indicate much work remains in therapies to achieve loco-regional control in locally advanced cases.     

The quantity of blood ingested by various species of fleas in an experiment

Data are given on the blood amount engorged by the fleas Xenopsylla conformis, X. cheopis, Leptopsylla segnis, Nosopsyllus laeviceps, N. consimilis, Ctenophthalmus golovi, Neopsylla setosa, Citellophilus tesquorum and Coptopsylla lamellifer. The average weight of blood portion in females of different species engorged for the first time ranged from 0.05 mg (X. conformis) to 0.72 mg (C. lamellifer). Females of most species, which had multiple blood meals, engorge more blood. Males engorge less blood than females and blood portions do not increase with age. In all sex-age groups most ectoparasites cease feeding spontaneously after having incomplete blood meal. Indices are suggested for the estimation of saturation rate in fleas during feeding.     

Bacterial shape maintenance: an evaluation of various models

In this article, we examine a large number of combinations of growth models, with separate attention to cell volume, cylindrical surface-area, polar caps, nascent poles, onset of constriction, precision of cell division and interdivision-time dispersion, for Escherichia coli cells growing in steady state at various doubling times. Our main conclusion is striking, and quite general: exponential cylindrical surface-area growth is not possible, irrespective of the behaviour of cell volume, the polar regions, the nascent poles, or any other feature of cell growth-such cells never reach steady state. The same is true of linear cylindrical surface-area growth, regardless of when during the cell cycle the doubling in growth rate takes place. Only after the introduction of feedback into the surface-area growth law, do the cultures attain steady state, all of them. The other components of the models contribute only marginally to the properties of the steady state. Thus, whether the feedback applies just to the cylindrical portion of the cell or to its entire surface area affects only the coefficient of variation of cell radius and the radius-volume correlation. The dynamics of old-pole maintenance, constant area or constant shape, influences the radius-length and radius-volume correlations and, to a much lesser extent, the coefficients of variation of cell radius and length; how the nascent poles grow, whether linearly or exponentially, does not seem to matter at all. The absolute dimensions of the cells are set by the growth rate of the culture and have almost no effect when the feedback is taken to apply to the entire cell surface area; when it is limited to the cylindrical portion of the cell, however, both radius-length and radius-volume correlations increase with increasing doubling time. Comparison with published values was inconclusive. The nature of cell surface-area growth has therefore been settled, but whether the volume increases by simple-exponential or by pseudo-exponential growth, or whether the old poles maintain a constant shape or a constant area during the cell cycle, can be determined only with more precise experimental data. The form of nascent-pole growth is not resolvable by present techniques.     

Biochemical aspects of basidiospore maturation in <Emphasis Type="Italic">Agaricus bisporus</Emphasis> at various temperatures

Phosphatidylethanolamine is the main phospholipid of Agaricus bisporus basidiospores obtained under sterile conditions from young basidiomes with closed partial veils. Storing the basidiospores for five months at room temperature resulted in a complete loss of their germinating capacity. Conversely, storing them at a low temperature increased their germination rate by 15–20%. At both temperature levels, the phosphatidyl-choline ratio significantly increased during storage to the level found in mature basidiospores. In addition, a drastic (8–10-fold) decrease in trehalose content occurred after two months of storage at room temperature. The trehalose content decreased only 1.5-fold at low temperatures. The involvement of trehalose and lipids in the retention of spore viability is discussed.     

Assisted large fragment insertion by Red/ET-recombination (ALFIRE)—an alternative and enhanced method for large fragment recombineering

Functional genomics require manipulation and modification of large fragments of the genome. Such manipulation has only recently become more efficient due to the discovery of different techniques based on homologous recombination. However, certain limitations of these strategies still exist since insertion of homology arms (HAs) is often based on amplification of DNA sequences with PCR. Large quantities of PCR products longer than 4–5kb can be difficult to obtain and the risk of mutations or mismatches increases with the size of the template that is being amplified. This can be overcome by adding HAs by conventional cloning techniques, but with large fragments such as entire genes the procedure becomes time-consuming and tedious. Second, homologous recombination techniques often require addition of antibiotic selection genes, which may not be desired in the final construct. Here, we report a method to overcome the size and selection marker limitations by a two- or three-step procedure. The method can insert any fragment into small or large episomes, without the need of an antibiotic selection gene. We have humanized the mouse luteinizing hormone receptor gene (Lhcgr) by inserting a ~55kb fragment from a BAC clone containing the human Lhcgr gene into a 170kb BAC clone comprising the entire mouse orthologue. The methodology is based on the rationale to introduce a counter-selection cassette flanked by unique restriction sites and HAs for the insert, into the vector that is modified. Upon enzymatic digestion, in vitro or in Escherichia coli, double-strand breaks are generated leading to recombination between the vector and the insert. The procedure described here is thus an additional powerful tool for manipulating large and complex genomic fragments.     

The use of small groups in a large lecture microbiology course

In the fall of 1997, we started using small groups in our large (100–200 students) junior level introductory microbiology course. Students form five-person groups early in the semester, and work on projects within these groups throughout the semester. These projects involve exploration of concepts such as metabolism, protein synthesis, and viral reproduction strategies and the submission of a poster describing a disease of their choice at the end of the semester. We have refined the use of the small groups during the last three semesters, and student acceptance and performance have improved steadily. In the fall semester of 1998, a comprehensive assessment of the effectiveness of these group projects was performed. Students were chosen at random to participate in student consultation groups to discuss group projects. Furthermore, we utilized a master teacher-in-residence from the Rocky Mountain Teachers Education Collaborative (RMTEC). This teacher-in-residence attended our classes, spoke with students, helped with student consultation groups, and provided observations of student responses to group work activities. RMTEC also provided funds to hire a research assistant to conduct student consultation groups, analyze student evaluations of our course, and compare evaluations from before and after the implementation of group examinations. Additionally, the Center for Teaching and Learning at Colorado State University assisted with mid-semester evaluations in each subsequent semester. The results of our analysis show that small groups in large lectures can be an effective learning tool provided students are given well-designed activities with clearly defined, obtainable goals and clearly articulated guidelines. Our experience also shows that the manner in which the instructor presents the process to students affects students' willingness to participate in the process. It must be clearly articulated to students why he has incorporated active learning strategies into the course, what he hopes students will gain from the experience, and how he expects students to participate in these activities. We recognize the increase in workload on ourselves as instructors, but the benefits seem worth the additional time and effort. This paper describes the group process that we use and provides an evaluation of the effort. Journal of Industrial Microbiology & Biotechnology (2000) 25, 121–126. Received 24 March 1999/ Accepted in revised form 23 November 1999     

Dynamics of microevolutionary processes during the use of pigs of various types under conditions at an industrial complex

Breeding of pigs in a closed herd during three generations under industrial complex conditions does not essentially increase the number of animals with homozygous genotypes of polymorphic systems of blood groups. One of the possible causes of this phenomenon is selection favourable to animals with a higher heterozygosity.