Crossing over is rarely associated with mitotic intragenic recombination in Schizosaccharomyces pombe.

Chromosomal rearrangements can result from crossing over during ectopic homologous recombination between dispersed repetitive DNA. We have previously shown that meiotic ectopic recombination between artificially dispersed ade6 heteroalleles in the fission yeast Schizosaccharomyces pombe frequently results in chromosomal rearrangements. The same recombination substrates have been studied in mitotic recombination. Ectopic recombination rates in haploids were approximately 1-4 x 10(-6) recombinants per cell generation, similar to allelic recombination rates in diploids. In contrast, ectopic recombination rates in heterozygous diploids were 2.5-70 times lower than allelic recombination or ectopic recombination in haploids. These results suggest that diploid-specific factors inhibit ectopic recombination. Very few crossovers occurred in ade6 mitotic recombination, either allelic or ectopic. Allelic intragenic recombination was associated with 2% crossing over, and ectopic recombination between multiple different pairing partners showed 1-7% crossing over. These results contrast sharply with the 35-65% crossovers associated with meiotic ade6 recombination and suggest either differential control of resolution of recombination intermediates or alternative pathways of recombination in mitosis and meiosis.

Glycosylation-dependent cell adhesion molecule 1 (GlyCAM 1) is induced by prolactin and suppressed by progesterone in mammary epithelium.

Glycosylation-dependent cell adhesion molecule 1 (GlyCAM 1), a mucin-like endothelial glycoprotein, was induced by PRL and suppressed by progesterone in the mammary gland of mice, and in HC11 mouse mammary epithelial cells. Complementary DNA microarray analysis revealed that expression of GlyCAM 1 was reduced in the mammary gland of PRL-gene disrupted mice (PRL-/-) compared with control (PRL+/-) littermates. This result was confirmed by in situ hybridization and immunostaining. The messenger RNA (mRNA) encoding GlyCAM 1 was present in mammary epithelia of PRL-stimulated mice. Immunohistochemistry indicated that GlyCAM 1 protein was detectable both in mammary epithelia and in the ductal lumen in PRL+/- virgin mice, but not in PRL-/- mice. GlyCAM 1 mRNA was highly induced by grafting pituitary glands from normal littermates. Trace amounts of mRNA for GlyCAM 1 were detected by RT-PCR in mammary tissue of PRL-/- mice. Progesterone inhibited both basal and PRL-stimulated GlyCAM 1 transcription. In HC11 cells, GlyCAM 1 mRNA was induced in cells treated with insulin, dexamethasone, and PRL. Similar to the in vivo studies, progesterone inhibited the induction of GlyCAM 1 transcription. In CHO cells, PRL stimulated transcription of a luciferase reporter gene containing an 800-bp promoter fragment of GlyCAM 1, and progesterone partially suppressed the PRL effect. These data demonstrate that expression of GlyCAM 1 in mammary gland is under the control of both PRL and progesterone.

Evolution of a new ecotype of Spartina alterniflora (Poaceae) in San Francisco Bay, California, USA.

We report the discovery and spread of a dwarf ecotype of Spartina alterniflora in San Francisco Bay. Relative to typical S. alterniflora, this dwarf ecotype has one-fifth the tiller height (∼21 cm), tenfold the tiller density (∼4000 tillers/m(2)), and is restricted to growth in the upper intertidal zone. Chromosome counts of the dwarfs are identical to typical smooth cordgrass (2n = 62), and smooth cordgrass-specific random amplified DNA markers confirm the species identity of the dwarf. Field-collected clonal fragments of the dwarf grown for 2 yr under high-nutrient conditions maintained the dwarf syndrome, as did plants grown from the seed of a dwarf. The dwarf condition is not caused by endophytic fungi. The first dwarf smooth cordgrass patch was discovered in 1991, and by 1996 five separate dwarf patches had appeared within 200 m of the original. Since 1991, total area covered by the dwarf ecotype has increased sixfold to 140 m(2). The ecological range of the dwarf smooth cordgrass ecotype is similar to that of S. patens, a competitor on the Atlantic coast. We suggest that the absence of S. patens from most of San Francisco Bay has allowed the dwarf ecotype of smooth cordgrass to survive and spread.

The M26 hotspot of Schizosaccharomyces pombe stimulates meiotic ectopic recombination and chromosomal rearrangements.

Homologous recombination is increased during meiosis between DNA sequences at the same chromosomal position (allelic recombination) and at different chromosomal positions (ectopic recombination). Recombination hotspots are important elements in controlling meiotic allelic recombination. We have used artificially dispersed copies of the ade6 gene in Schizosaccharomyces pombe to study hotspot activity in meiotic ectopic recombination. Ectopic recombination was reduced 10-1000-fold relative to allelic recombination, and was similar to the low frequency of ectopic recombination between naturally repeated sequences in S. pombe. The M26 hotspot was active in ectopic recombination in some, but not all, integration sites, with the same pattern of activity and inactivity in ectopic and allelic recombination. Crossing over in ectopic recombination, resulting in chromosomal rearrangements, was associated with 35-60% of recombination events and was stimulated 12-fold by M26. These results suggest overlap in the mechanisms of ectopic and allelic recombination and indicate that hotspots can stimulate chromosomal rearrangements.

Pustulotic arthro-osteitis: a cause of atypical chest pain and a new arthritic syndrome.

We have described a 38-year-old white American woman who had a 7-year history of pain in the left anterior chest, neck, right wrist, and buttocks. The pain fluctuated in severity and appeared to coincide with worsening of her skin condition, palmoplantar pustulosis (PPP). She manifested the typical skeletal features of an arthritic condition referred to as pustulotic arthro-osteitis, which is frequently associated with the characteristic rash of PPP. This is an infrequently described disorder in the United States, possibly reflecting lack of familiarity or confusion with related disorders.

Synthesis and structure-activity relationships of cephalosporins with C-3' catechol-containing residues.

Cephalosporins with new catechol substituents at C-3' have been synthesized, including novel compounds with C-3' carbon-carbon bonds. Many of these compounds have high potency against Gram-negative bacteria, in particular against resistant strains like Pseudomonas aeruginosa. Structure-activity relationships are discussed in terms of their dependence on the pKa of the C-3' catechol and also in terms of steric and conformational factors of the C-3' substituent. The best overall properties were found in compounds with a bulky and/or conformationally restricted acidic C-3' catechol.

Prospective randomized trial of sequential compression devices vs low-dose warfarin for deep venous thrombosis prophylaxis in total hip arthroplasty.

A prospective randomized trial compared the effectiveness of low-dose warfarin (LDW) to sequential compression devices (SCD) for deep venous thrombosis (DVT) prophylaxis in 95 patients after total hip arthroplasty (THA). Patients were 39 years of age or older, with no history of previous venous disease. Bilateral lower-extremity venography was used for thrombi detection. Venous thrombi occurred in 12 patients (all calf) on LDW (26.6%) and 3 patients with SCDs (one calf, two thigh) (6.0%). The incidence of DVT was significantly higher in the LDW group (P less than .006). In this study of average-risk patients, the use of SCDs significantly outperformed LDW as a prophylactic agent. However, the thrombi that did occur with SCDs were more critical.

Diffuse nail dyschromia in black patients with systemic lupus erythematosus.

Diffuse dark blue-black chromonychia was observed in 17 of 33 (52%) black patients with systemic lupus erythematosus (SLE), but not in 47 non-SLE black patients. About half of these patients had active disease. A comparison was made between patients with SLE with chromonychia and those without but no distinctive clinical or laboratory variable differentiated the 2 groups. This pattern of nail hyperpigmentation has not previously been associated with SLE.

Comparison of the vigilance performance of men and women using a simulated radar task.

The present study examined the question of possible sex differences in the ability to sustain attention to a complex monitoring task requiring only a detection response to critical stimulus changes. The visual display was designed to approximate a futuristic, highly automated air traffic control radar display containing computer-generated alphanumeric symbols. There were 26 men and 26 women tested, each over a 2-h session. Sixteen targets appeared on the screen at all times, with 10 signals (a designated change in the alphanumerics) randomly presented during each 0.5 h of the test session. Detection latency to the signals increased significantly during the session, but there was no evidence of any significant differences between the sexes in the magnitude or pattern of this increase. The results are discussed in terms of a general decline in alertness that was apparently equal for both sexes.