Progesterone induces expression of endometrial messenger RNA encoding for cyclooxygenase (sheep)

Exogenous progesterone given early in the ovine estrous cycle results in precocious luteolysis. It has been suggested that under this circumstance regression of the corpus luteum is caused by an advancement in the timing of uterine secretion of prostaglandin F2 alpha. Uterine tissues were obtained from ewes following administration of progesterone (or injection vehicle), fixed in paraformaldehyde, and embedded in paraffin. Tissue sections were hybridized using an 35S-labeled cRNA probe specific for cyclooxygenase mRNA. There was approximately an eight-fold increase in the level of hybridization signal, localized mainly to uterine glands, consequential to treatment with progesterone. Thus, progesterone appears to control expression of the endometrial gene and(or) the stability of the message encoding for a rate-limiting enzyme involved in metabolism of arachidonic acid to its luteolytic product, thereby resolving the length of the nonpregnant cycle.     

Single cell studies of the cell cycle and some models

Analysis of growth and division often involves measurements made on cell populations, which tend to average data. The value of single cell analysis needs to be appreciated, and models based on findings from single cells should be taken into greater consideration in our understanding of the way in which cell size and division are co-ordinated. Examples are given of some single cell analyses in mammalian cells, yeast and other microorganisms. There is also a short discussion on how far the results are in accord with simple models.     

Beta-cell function and islet morphology in normal, obese, and obese beta-cell mass-reduced Göttingen minipigs

Herein, we bridge beta-cell function and morphology in minipigs. We hypothesized that different aspects of beta-cell dysfunction are present in obesity and obesity with reduced beta-cell mass by using pulsatile insulin secretion as an early marker. Measures for beta-cell function (glucose and arginine stimulation plus baseline and glucose-entrained pulsatile insulin secretion) and islet morphology were studied in long-term (19-20 mo) obese (n = 5) and obese beta-cell-reduced [nicotinamide + streptozotocin (STZ), n = 5] minipigs and normal controls, representing different stages in the development toward type 2 diabetes. Acute insulin response (AIR) to glucose and arginine were, surprisingly, normal in obese (0.3 g/kg glucose: AIR = 246 +/- 119 vs. 255 +/- 61 pM in control; 67 mg/kg arginine: AIR = 230 +/- 124 vs. 214 +/- 85 pM in control) but reduced in obese-STZ animals (0.3 g/kg glucose: AIR = 22 +/- 36, P < 0.01; arginine: AIR = 87 +/- 92 pM, P < 0.05 vs. control). Baseline pulsatile insulin secretion was reduced in obese (59 +/- 16 vs. 76 +/- 16% in control, P < 0.05) and more so in obese-STZ animals (43 +/- 13%, P < 0.01), whereas regularity during entrainment was increased in obese animals (approximate entropy: 0.85 +/- 0.14 vs. 1.13 +/- 0.13 in control, P < 0.01). Beta-cell mass (mg/kg body wt) was normal in obese and reduced in obese-STZ animals, with pancreatic fat infiltration in both groups. In conclusion, obesity and insulin resistance are not linked with a general reduction of beta-cell function, but dynamics of insulin secretion are perturbed. The data suggest a sequence in the development of beta-cell dysfunction, with the three groups representing stages in the progression from normal physiology to diabetes, and assessment of pulsatility as the single most sensitive marker of beta-cell dysfunction.     

An approach to large scale identification of non-obvious structural similarities between proteins

Background

A new sequence independent bioinformatics approach allowing genome-wide search for proteins with similar three dimensional structures has been developed. By utilizing the numerical output of the sequence threading it establishes putative non-obvious structural similarities between proteins. When applied to the testing set of proteins with known three dimensional structures the developed approach was able to recognize structurally similar proteins with high accuracy.

Results

The method has been developed to identify pathogenic proteins with low sequence identity and high structural similarity to host analogues. Such protein structure relationships would be hypothesized to arise through convergent evolution or through ancient horizontal gene transfer events, now undetectable using current sequence alignment techniques. The pathogen proteins, which could mimic or interfere with host activities, would represent candidate virulence factors.The developed approach utilizes the numerical outputs from the sequence-structure threading. It identifies the potential structural similarity between a pair of proteins by correlating the threading scores of the corresponding two primary sequences against the library of the standard folds. This approach allowed up to 64% sensitivity and 99.9% specificity in distinguishing protein pairs with high structural similarity.

Conclusion

Preliminary results obtained by comparison of the genomes of Homo sapiens and several strains of Chlamydia trachomatis have demonstrated the potential usefulness of the method in the identification of bacterial proteins with known or potential roles in virulence.

     

Development of three different gene cloning systems for genetic investigation of the new species Amycolatopsis japonicum MG417-CF17, the ethylenediaminedisuccinic acid producer

For the first time gene cloning systems have been developed for Amycolatopsis japonicum. Direct transformation, polyethyleneglycol (PEG) induced protoplast transformation and conjugal transfer was established for A. japonicum MG417-CF17, the ethylenediaminedisuccinic acid (EDDS) producer. The direct transformation procedure was modified to introduce DNA. The most important parameter for an efficient DNA uptake was the age of the culture. Using of mycelium from 36-h old cultures resulted in the highest transformation frequencies. Further, conditions for transformation of A. japonicum protoplasts were established. The efficiency of transformation depended mainly on the source of PEG and the components of the regeneration agar. The replicative plasmid pULVK2A carrying pA-rep and the apramycin resistance gene was transferred into the EDDS producer with a frequency of 0.38 colonies microg(-1) DNA by using the direct transformation procedure and with a frequency of 0.56 colonies microg(-1) DNA by using the PEG induced protoplast transformation. The plasmid was genetically stable, and could easily be reisolated from A. japonicum. We also demonstrated that conjugal transfer of the plasmid pSET152 from Escherichia coli ET12567 (pUB307) to Amycolatopsis spores is possible. The plasmid pSET152 integrated in the A. japonicum chromosome. A titre of 2.4 x 10(-4) exconjugants per recipient was obtained.     

Heterostyly in the Lamiaceae: The case ofSalvia brandegeei

Heterostyly rarely occurs in families with strongly zygomorphic flowers. For this reason Darwin (1877) doubted whether heterostyly would occur in the Lamiaceae and recent reviews have not reported the floral polymorphism in this family. Here we describe distyly in a rare species ofSalvia restricted to bluffs and seaward canyons on Santa Rosa Island (Santa Barbara Co., California) and northwestern Baja California (Mexico).Salvia brandegeei is morphologically distylous with populations composed of equal frequencies of long-and short-styled morphs differing reciprocally in stigma and anther position. Controlled hand pollinations demonstrated no significant differences in the seed set of self, intramorph or intermorph pollinations. Unlike most heterostylous species investigated,S. brandegeei does not possess diallelic incompatibility or ancillary polymorphisms of pollen and stigmas. We propose that the evolution of distyly inS. brandegeei may have been associated with an ecological shift to a new environment in which protandry failed to prevent increased levels of geitonogamy. Heterostyly was then selected because it increased the proficiency of cross-pollination. The origin of distyly in self-compatibleS. brandegeei is consistent with Lloyd and Webb's theoretical model for the evolution of distyly.