Biotransformation of 2,2-Dimethyl-1,3-Propanediol to 3-Hydroxypivalic Acid by Acetobacter Acetii DSMZ3508 and Related Bacteria

Acetobacter acetii DSMZ3508 and related bacteria converted 2,2-dimethyl-1,3-propanediol into 3-hydroxypivalic acid (2,2-dimethyl-3-hydroxypropionic acid; 3HP) during submerged cultivation in mineral salt medium. The maximum yield of 3-hydroxypivalic acid was 24.4% of the fed substrate after 18 days. Cultivation parameters, as pH, cell density, optimal substrate concentration, and oxygen supply for the bioconversion process were determined.     

A planar microtubule-organizing zone in guard cells of Allium: experimental depolymerization and reassembly of microtubules

The generation of the unique radial array of microtubules (MTs) in stomatal guard cells raises questions about the location and activities of relevant MT-organizing centers. By using tubulin immunofluorescence microscopy, we studied the pattern of depolymerization and reassembly of MTs in guard cells of Allium cepa L. Chilling at 0°C reduces the MTs to small remnants that surround the nuclear surface of cells in the early postcytokinetic stage, or form a dense layer along the central portion of the ventral wall in older guard cells. A rapid reassembly on rewarming restores either MTs extending from the nuclear surface randomly throughout the cytoplasm in very young cells, or an array of MTs radiating from the dense layer at the ventral wall later in development. A similar pattern of depolymerization and reassembly is achieved by incubation with 100 M colchicine followed by a brief irradiation with ultraviolet (UV) light. Incubation with 200 M colchicine leads to a complete depolymerization that leaves only a uniform, diffuse cytoplasmic fluorescence. Nonetheless, UV irradiation of developing guard cells induces the regeneration of a dense layer of MTs at the ventral wall. The layer is again positioned centrally along the wall, even if the nucleus has been displaced by centrifugation in the presence of cytochalasin D. Neither the regenerated layer nor the perinuclear MTs seen earlier are related to the staining pattern of serum 5051, which reportedly binds to centrosomal material in animal and plant cells. The results support the view that, soon after cytokinesis, a planar MT-organizing zone is established in the cortex along the central portion of the ventral wall, which then generates the radial MT array.Abbreviations GC guard cell - MT microtubule - MTOC microtubule-organizing center - UV ultraviolet To whom correspondence should be addressed.     

Chlamydosporol,a new metabolite from Fusarium chlamydosporum

Extracts of rice on which an isolate of Fusarium chlamydosporum had been cultured were toxic to brine shrimps. The toxic fraction was purified by flash chromatography to give two compounds which were identified by UV, IR, NMR and mass spectroscopy at the 6 and 6 isomers of 5-hydroxy-4-methoxy-6, 8a-dimethyl-6,7-dihydro-2H,8aH-pyrano[2,3-b]pyran-2-one. These lactones for which the name chlamydosporol is proposed have not been reported previously. When tested in brine shrimp and HeLa cell assays, the LC₅₀ concentration for a mixture of the isomers was approximately 400 g/ml in both systems.     

Diagnosis of abdominal masses with percutaneous biopsy guided by ultrasound.

OBJECTIVE--To assess the accuracy and safety of percutaneous biopsy of abdominal masses guided by ultrasound. DESIGN--Prospective study. SETTING--Combined gastroenterology service, Scarborough Hospital. PATIENTS--108 Consecutive patients identified as having a discrete mass on diagnostic ultrasound examination of the abdomen. INTERVENTION--A sample of tissue was obtained with an aseptic technique under local anaesthesia: an 18 steel wire gauge needle (Tru-Cut) was mounted in a spring loaded firing device (Biopty gun) that was advanced under simultaneous ultrasound scanning, permitting precise localisation of the target organ. MAIN OUTCOME MEASURE--Results of histological examination of tissue specimens. RESULTS--Biopsy failed in four patients. Adequate histological specimens were obtained in 104 patients with masses in the liver (31), pancreas (37), kidney (10), and adrenal glands (six) and in 20 undiagnosed abdominal and retroperitoneal masses. Follow up was until death or confirmation of the diagnosis. Three complications but no deaths occurred. Malignancy was suspected in 84 patients before biopsy. This was confirmed in 70 patients, in 26 of whom confirmation of dissemination obviated the need for further investigation. In 10 patients biopsy indicated a previously unsuspected primary tumour, and in 12 it showed only a benign lesion. Among 24 patients considered to have benign disease biopsy showed an unsuspected neoplasm in seven. Use of biopsy thus had a major effect on clinical management in 55 patients. Four false negative but no false positive diagnoses resulted from the procedure. CONCLUSION--Percutaneous biopsy of abdominal and retroperitoneal masses under ultrasound guidance is a safe and accurate method of obtaining a histological diagnosis. The results obtained have a considerable effect on clinical management.     

On the evolutionary ecology of marking pheromones

Summary Many parasitic insects mark hosts with a pheromone after oviposition. The evolutionary ecology of such marking pheromones was studied to determine (i) under what ecological and behavioral conditions such pheromones could evolve and (ii) why so many of these marking pheromones are water-soluble and thus short-lived. We used a number of different techniques. First, the fitness values of individual normal (nonmarking) and mutant (marking) insects foraging for hosts were computed using dynamic state-variable models. Second, population level models were used to study when a population of non-marking individuals can be invaded by marking individuals. Third, behavior-rich simulations (developed originally for apple maggot,Rhagoletis pomonella) were used to test experimentally some of the hypotheses generated using the individual and population-level models. Finally, we developed a model for the benefit over time to an individual by marking. This model shows that when benefit is measured in terms of larval survival, nearly all of the benefit to a mother is obtained from short-lived marks. Genetical theories of pheromone evolution and the connection between our results and existing theories of altruistic behavior are discussed.     

The intron 7 donor splice site transition: a second Tay-Sachs disease mutation in French Canada

Mutations at the hexosaminidase A (HEXA) gene which cause Tay-Sachs disease (TSD) have elevated frequency in the Ashkenazi Jewish and French-Canadian populations. We report a novel TSD allele in the French-Canadian population associated with the infantile form of the disease. The mutation, a GA transition at the +1 position of intron 7, abolishes the donor splice site. Cultured human fibroblasts from a compound heterozygote for this transition (and for a deletion mutation) produce no detectable HEXA mRNA. The intron 7+1 mutation occurs in the base adjacent to the site of the adult-onset TSD mutation (G805A). In both mutations a restriction site for the endonuclease EcoRII is abolished. Unambiguous diagnosis, therefore, requires allele-specific oligonucleotide hybridization to distinguish between these two mutant alleles. The intron 7+1 mutation has been detected in three unrelated families. Obligate heterozygotes for the intron 7+1 mutation were born in the Saguenay-Lac-St-Jean region of Quebec. The most recent ancestors common to obligate carriers of this mutation were from the Charlevoix region of the province of Quebec. This mutation thus has a different geographic centre of diffusion and is probably less common than the exon 1 deletion TSD mutation in French Canadians. Neither mutation has been detected in France, the ancestral homeland of French Canada.