SUMMARYMalate, along with potassium and chloride ions, is an important solute for maintaining turgor pressure during stomatal opening. Although malate is exported from guard cells during stomatal closure, there is controversy as to whether malate is also metabolised. We provide evidence that phosphoenolpyruvate carboxykinase (PEPCK), an enzyme involved in malate metabolism and gluconeogenesis, is necessary for full stomatal closure in the dark. Analysis of the Arabidopsis PCK1 gene promoter indicated that this PEPCK isoform is specifically expressed in guard cells and trichomes of the leaf. Spatially distinct promoter elements were found to be required for post-germinative, vascular expression and guard cell/trichome expression of PCK1. We show that pck1 mutant plants have reduced drought tolerance, and show increased stomatal conductance and wider stomatal apertures compared with the wild type. During light-dark transients the PEPCK mutant plants show both increased overall stomatal conductance and less responsiveness of the stomata to darkness than the wild type, indicating that stomata get 'jammed' in the open position. These results show that malate metabolism is important during dark-induced stomatal closure and that PEPCK is involved in this process.

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Comprehensive quality control procedures were integrated into the routine semen analysis workload of a large university-based andrology laboratory. Methods were chosen to match as far as possible those which have been used successfully for many years in disciplines such as clinical chemistry. Levey-Jennings and cusum charts were plotted in order to monitor the immunobead-binding test for antisperm antibodies and a video-taped control sample for computerized semen analysis. A cryopreserved semen control was also charted. Daily manual sperm counts were plotted against the corresponding computer-assisted semen analysis (CASA) value. Multiple readings of 30 slides were used to monitor morphology assessments. Monthly means for morphology were also calculated regularly. Coefficients of variation were calculated for all variables and were found to be more appropriate for some aspects, such as CASA, than for others, such as morphology, when difference from the previous reading of the same slide was found to be more useful. These integrated quality control procedures had a direct influence on the production of results from the laboratory. Together with a high standard of technician training, comprehensive routine quality control based on repeated analyses of control samples is an effective way of assuring the validity of semen analysis results.

The World Health Organization (WHO, 1992) has suggested new criteria for scoring sperm morphology. This study compares the clinical value of the new criteria, i.e. classification of a man as fertile or infertile, to those previously established by the WHO (1987). Papanicolaou-stained semen smears from 166 men attending our infertility clinic, whose fertility status was known, were scored using both methods. Using logistic discriminant analysis for compositional data, no difference between these two sets of criteria with respect to predicting pregnancy outcome was observed. The categorization of the abnormalities (head, midpiece, tail) provides no extra clarification. The WHO (1992) cut-off point of 30% for normal forms is not appropriate, as approximately half of the men in the fertile group had a normal sperm morphology below this limit. In conclusion, the present WHO (1992) classification of sperm morphology is of no additional clinical value. Studies on sperm morphology should concentrate on obtaining biological data on, and measurements of, spermatozoa which are functionally active. Only then can the definition of normal be achieved and clinically useful criteria be adopted.

BackgroundPart-time training (PTT) is accessed by approximately 10% of Australian obstetrics and gynaecology trainees, a small but increasing minority which reflects the growing demand for improved work/life balance amongst the Australian medical workforce. This survey reports the attitudes and experiences of both full-time and part-time trainees to PTT.MethodsAn email-based anonymous survey was sent to all Australian obstetrics and gynaecology trainees in April 2009, collecting demographic and training status data, data on personal experiences of PTT and/or trainees, and attitudes towards PTT.Results105 responses were received (20% response rate). These indicated strong support (90%) from both full-time (FT) and part-time (PT) trainees for the availability of PTT. PT trainees were significantly more likely than FT trainees to be female with children. Improved morale was seen as a particular advantage of PTT; decreased continuity of care as a disadvantage.ConclusionsAlthough limited by poor response rate, both PT and FT Australian obstetric trainees were supportive of part-time training. Both groups recognised important advantages and disadvantages of this mode of training. Currently, part-time training is accessed primarily by female trainees with family responsibilities, with many more trainees considering part-time training than the number that access it.