Congression of achiasmate chromosomes to the metaphase plate in Drosophila melanogaster oocytes

Chiasmata established by recombination are normally sufficient to ensure accurate chromosome segregation during meiosis by physically interlocking homologs until anaphase I. Drosophila melanogaster female meiosis is unusual in that it is both exceptionally tolerant of nonexchange chromosomes and competent in ensuring their proper segregation. As first noted by Puro and Nokkala [Puro, J., Nokkala, S., 1977. Meiotic segregation of chromosomes in Drosophila melanogaster oocytes. A cytological approach. Chromosoma 63, 273-286], nonexchange chromosomes move precociously towards the poles following formation of a bipolar spindle. Indeed, metaphase arrest has been previously defined as the stage at which nonexchange homologs are symmetrically positioned between the main chromosome mass and the poles of the spindle. Here we use studies of both fixed images and living oocytes to show that the stage in which achiasmate chromosomes are separated from the main mass does not in fact define metaphase arrest, but rather is a component of an extended prometaphase. At the end of prometaphase, the nonexchange chromosomes retract into the main chromosome mass, which is tightly repackaged with properly co-oriented centromeres. This repackaged state is the true metaphase arrest configuration in Drosophila female meiosis.     

Survival and Reproduction of Myxobolus cerebralis-Resistant Rainbow Trout Introduced to the Colorado River and Increased Resistance of Age-0 Progeny

Myxobolus cerebralis caused severe declines in rainbow trout populations across Colorado following its introduction in the 1980s. One promising approach for the recovery of Colorado’s rainbow trout populations has been the production of rainbow trout that are genetically resistant to the parasite. We introduced one of these resistant crosses, known as the GR×CRR (cross between the German Rainbow [GR] and Colorado River Rainbow [CRR] trout strains), to the upper Colorado River. The abundance, survival, and growth of the stocked GR×CRR population was examined to determine if GR×CRRs had contributed offspring to the age-0 population, and determine whether these offspring displayed increased resistance and survival characteristics compared to their wild CRR counterparts. Apparent survival of the introduced GR×CRR over the entire study period was estimated to be 0.007 (±0.001). Despite low survival of the GR×CRRs, age-0 progeny of the GR×CRR were encountered in years 2008 through 2011. Genetic assignments revealed a shift in the genetic composition of the rainbow trout fry population over time, with CRR fish comprising the entirety of the fry population in 2007, and GR-cross fish comprising nearly 80% of the fry population in 2011. A decrease in average infection severity (myxospores fish⁻¹) was observed concurrent with the shift in the genetic composition of the rainbow trout fry population, decreasing from an average of 47,708 (±8,950) myxospores fish⁻¹ in 2009 to 2,672 (±4,379) myxospores fish⁻¹ in 2011. Results from this experiment suggest that the GR×CRR can survive and reproduce in rivers with a high prevalence of M. cerebralis. In addition, reduced myxospore burdens in age-0 fish indicated that stocking this cross may ultimately lead to an overall reduction in infection prevalence and severity in the salmonid populations of the upper Colorado River.     

Studies on the mode of action of calciferol: Biological activity of 1α,24R,25-trihydroxyvitamin D3 in the chick

The biological activity of 1α,24R,25-trihydroxyvitamin D₃ [1α,24R,25(OH)₃D₃] was elevated in comparison to the hormonally active form of vitamin D₃, 1α,25-dihydroxyvitamin D₃ [1α,25(OH)₂D₃], in the rachitic chick in terms of its ability to (a) stimulate intestinal calcium absorption, (b) mobilize bone calcium, (c) induce intestinal calcium binding protein, (d) modulate the level of enzyme activity of the renal 25-OH-D₃-1-hydroxylase system, and (e) interact with the intestinal cystosol-chromatin receptor system for the 1α,25(OH)₂D₃ receptor system. In each of these assays, the relative ratio of activity of 1α,24R,25(OH)₃D₃ to 1α,25(OH)₂D₃was (a) 25–50, (b) ca. 20, (c) 10, (d) 50, and (e) 36%, respectively.     

Formation, localization, and repair of L-isoaspartyl sites in histones H2A and H2B in nucleosomes from rat liver and chicken erythrocytes

Formation of l-isoaspartyl (isoAsp) peptide bonds is a major source of protein damage in vivo and in vitro. Accumulation of isoAsp in cells is limited by a ubiquitous repair enzyme, protein l-isoaspartyl methyltransferase (PIMT). Reduction of PIMT activity in mouse brain or rat PC12 cells leads to a dramatic and selective accumulation of isoAsp sites in histone H2B. To learn more about the mechanism and specificity of isoAsp formation in histones, we purified mononucleosomes from rat liver and chicken erythrocytes and subjected them to in vitro aging for 0-16 days. In rat nucleosomes, the pattern of isoAsp accumulation duplicated that observed in vivo; only H2B accumulated significant isoAsp that we have now localized to the Asp25-Gly26 bond in the N-terminal tail. In chicken nucleosomes, isoAsp accumulated mainly in histone H2A and, to a lesser extent, in histone H2B. Minor sequence differences are consistent with the species-specific patterns of isoAsp accumulation and suggest that, in chicken, isoAsp occurs at the Asp121-Ser122 bond in the flexible C-terminal tail of H2A and at the Asp26-Lys27 bond in the N-terminal tail of H2B. The aging-induced accumulation of isoAsp in rat and chicken nucleosomes is repaired upon incubation of the damaged nucleosomes with PIMT and AdoMet. Our findings suggest that in vivo generation of isoAsp sites in histones occurs as a self-catalyzed process at the level of the nucleosome and is driven by the same structural features that have been shown to promote isoAsp formation in purified proteins and synthetic peptides.     

Free tissue coverage of chronic traumatic wounds of the lower leg

Thirty-eight consecutive patients who underwent 42 free flaps for chronic wounds of the lower leg were identified over an 11-year period. All wounds were open for a minimum of 1 month (mean, 40 months; median, 8 months; range, 1 month to 30 years). The average age was 37 years (range, 7 to 68 years), there were 31 male patients and seven female patients, and the average follow-up time was 30 months (range, 12 to 72 months). The original injury was an open fracture in 28 patients, wound dehiscence after open reduction and internal fixation of a closed fracture in nine patients, and a shrapnel wound in one patient. A total of 23 patients had osteomyelitis, which was classified as local (involving less than 50 percent of the bone diameter) in 15 patients and as diffuse (involving greater than 50 percent of the bone diameter or infected nonunion) in eight patients. The wounds were treated with sequential debridement, antibiotics, and flap coverage. Ancillary procedures included antibiotic beads in 18 patients, saucerization in 16, Ilizarov bone transport in three, calcanectomy in two, and fibular resection and ankle fusion in one. Thirty-four of 42 flaps survived, four having undergone a repeat free flap. There were three failures out of 25 flaps (12 percent) among those with a normal angiogram and five failures out of 15 flaps (33 percent) among those with an abnormal angiogram (p > 0.05). The failure rate of those with osteomyelitis was six of 26 (23 percent) versus two of 26 (13 percent) for those without osteomyelitis (p > 0.05). Successful reconstruction (bone healed, patient ambulatory and infection-free) was achieved in 33 of 38 patients (87 percent). The failure of reconstruction for those patients with osteomyelitis was four of 23 (22 percent) versus one of 15 (7 percent) for others (p > 0.05). The failure rate of flaps in patients with diffuse osteomyelitis was three of eight (38 percent) versus two of 30 for others (7 percent, p = 0.053). The presence of diffuse osteomyelitis was associated with a lower rate of successful limb reconstruction. An abnormal angiogram and the presence of osteomyelitis both were associated with a lower rate of successful limb reconstruction, but this was not significant, probably because of the small size of the cohort.     

An european pupil project linked to the scientific aims of the experiment AQUARIUS-XENOPUS on the taxi Soyuz flight Andromede to ISS

The German-French biological experiment AQUARIUS-XENOPUS which flew on the Soyuz flight Andromede to the International Space Station ISS (launched October 21, 2001 in Baikonour/Kazakhstan) was extended by an outreach project. Pupils of class 10 to 12 from Ulm/D and Nancy-Tomblaine/F studied swimming behavior of Xenopus tadpoles on ground. They were instructed to perform all experimental steps following the protocol of similar video recordings on ISS. After the flight, they evaluated the kinetics of swimming of both ground controls and space animals. The pupil project included theoretical components to introduce them to the field of gravitational biology. One feature of the project was the exchange of ideas between pupils by meetings which took place in Ulm (June 2001), Nancy (February 2002) and Paris (May 2002). We consider our approach as a successful way to include young people in space experiments on a cheap cost level and to bring ideas of gravitational biology into the curricula of European schools.     

Morphometrics within dog breeds are highly reproducible and dispute Rensch’s rule

Using 27 body measurements, we have identified 13 breed-defining metrics for 109 of 159 domestic dog breeds, most of which are recognized by the American Kennel Club (AKC). The data set included 1,155 dogs at least 1 year old (average 5.4 years), and for 53 breed populations, complete measurement data were collected from at least three males and three females. We demonstrate, first, that AKC breed standards are rigorously adhered to for most domestic breeds with little variation observed within breeds. Second, Rensch’s rule, which describes a scaling among taxa such that sexual dimorphism is greater among larger species if males are the larger sex, with less pronounced differences in male versus female body size in smaller species, is not maintained in domestic dog breeds because the proportional size difference between males and females of small and large breeds is essentially the same. Finally, principal components (PCs) analysis describes both the overall body size (PC1) and the shape (length versus width) of the skeleton (PC2). That the integrity of the data set is sufficiently rich to discern PCs has strong implications for mapping studies, suggesting that individual measurements may not be needed for genetic studies of morphologic traits, particularly in the case of breed-defining traits that are typically under strong selection. Rather, phenotypes derived from data sets such as these, collected at a fraction of the effort and cost, may be used to direct whole-genome association studies aimed at understanding the genetic basis of fixed morphologic phenotypes defining distinct dog breeds.     

Comparison of the Escherichia coli proteomes for recombinant human growth hormone producing and nonproducing fermentations

Two-dimensional electrophoretic analyses of Escherichia coli cells producing recombinant human growth hormone (Nutropin) in fermentations were conducted. The resulting two-dimensional protein profiles were compared with those of nonproducing (blank) cells. A qualitative comparison was performed to address regulatory issues in the biopharmaceutical industry, and a semiquantitative comparison was performed to reveal information about the physiological state of the cells. The protein spots unique to production fermentation profiles were all related to recombinant human growth hormone (hGH); these included intact hGH, charge variants of hGH, and a proteolytically cleaved form of hGH, as expected. There were no E. coli host cell proteins unique to either the production or blank fermentation profiles. Rather, all detectable differences in E. coli proteins were quantitative in nature. Specifically, the levels of IbpA (inclusion body binding protein A), Ivy (inhibitor of vertebrate lysozyme), and a cleaved form of GroEL (Hsp60 homolog) were higher in hGH production profiles, whereas the levels of GlmU protein and PspA (phage shock protein A) were higher in blank profiles. In general, the high degree of similarity between proteomes for hGH-producing and nonproducing cells suggests that E. coli proteins from a nonproducing (blank) fermentation are appropriate for eliciting antibodies that are then used in immunoassays to measure host cell proteins in samples from production fermentations.