Establishment of the block against sperm penetration in parthenogenetically activated bovine oocytes matured in vitro

It was demonstrated previously that replication of plasmids derived from bacteriophage lambda (so-called lambda plasmids) is inhibited in wild-type Escherichia coli cells starved for isoleucine and arginine whereas it proceeds under the same conditions in relA mutants. Since replication of other replicons during the stringent or relaxed response depends on the nature of the deprived amino acid, we investigated replication of lambda plasmids in E. coli relA+ and relA- strains starved for different amino acids. We found that replication of lambda plasmids is generally inhibited during the stringent, but not relaxed, response. Differences between cells starved for different amino acids, although reproducible, were not dramatic. Amino acid starvation was previously proposed as a method for amplification of lambda plasmid DNA in vivo. We found that during amino acid limitation lambda plasmids replicate more extensively in the relA mutants than during amino acid starvation. The efficiency of plasmid DNA amplification was found to be dependent on the kind of limited amino acid; in relA- bacteria limited for leucine we observed about 10-fold plasmid amplification. Some lambda plasmid replication was also found under these conditions in the relA+ host. The mechanism of the stringent control of lambda plasmid DNA replication has already been proposed. Here the possible mechanism of the regulation of lambda plasmid replication during amino acid limitation is presented.     

The dumping valve and its clinical application

An open reservoir for the collection and evacuation of anaesthetic gases permits leakage to room air. The use of a closed reservior for the removal of overspill gas from anaesthetic circuits is described. Calibrated gas evacuation is carried out through an ejector flowmeter from the anesthetic circuit or from a closed reservoir, where the gas is collected via a relief valve. In order to eliminate the risk of high or low pressure in the reservoir employed, a relief valve and a dumping valve is included in the system.     

Diurnal variation of nasal protein concentration

In normal subjects a marked diurnal variation was disclosed in the concentrations of immunoglobulin G (IgG), IgA and albumin in nasal secretion, the night values being 4.5-5.5 times higher than those during the day. It is suggested that this is due to changing secretory activity of the nasal glands.     

Lymphocyte transformation in vitro in dermatophytosis

Peripheral blood lymphocytes from 59 patients with dermatophytosis and from nine young healthy women were studied by the lymphocyte transformation test (LT) using mitogens and bacterial as well as fungal antigens. The latter included Candida albicans (CA) and four dermatophyte species, viz. Trichophyton rubrum (TR), Trichophyton mentagrophytes (TM), Epidermophyton floccosum (EF) and Microsporum canis (MF). Most of the patients showed normal transformation in response to mitogens and non-dermatophyte antigens, indicating that they have no functional T-cell deficiency. Dermatophyte antigens act as stimulators in LT. In general, patient lymphocytes responded more strongly to these antigens than lymphocytes from controls. In most patients suffering from TM infections, response to the TM antigen was significantly stronger (p less than 0.05) than that in the other patients, indicating that this antigen preparation shows species specificity. In patients with Trichophyton (TR + TM) infections, response to the corresponding antigens was significantly stronger than that in the other patients, which suggests the existence of genus specificity. Any differences between patients suffering from chronic TR infections and those with acute TR infections were not observed, a finding which is in contrast to those obtained in other studies. However, a few patients with chronic TM infections responded weakly to mitogens and non-dermatophyte antigens. LT in four patients with id-reaction to TM infection was not found to differ from that in the remaining TM patients.     

Comparison of candicidin, levorin and trichomycin by means of high-performance liquid chromatography

A high-performance liquid chromatographic method for the separation of individual components of polyene macrolide antibiotics has been developed. The three heptaene macrolide antibiotics, candicidin, levorin and trichomycin, have been investigated and compared. In all instances these compounds proved to be complex mixtures. It is demonstrated that candicidin and levorin are identical, whereas trichomycin differs in composition from these two substances.     

Benzene-induced genotoxicity in mice in vivo detected by the alkaline comet assay: reduction by CYP2E1 inhibition

Acute, severe injury of the rabbit spinal cord, induced by the weight-drop method, causes alterations of the enzyme activities related to cholinergic and energy metabolism. Morphological examinations at the trauma site show degenerative processes in neurons 0.5 hr posttrauma and a marked decrease in the number of living cells 24 hrs later. Both biochemical and cytochemical findings show that the tissue metabolic and morphologic derangement, caused by severe spinal cord injury, is mostly confined to the gray matter at an early stage (0.5 hr), whereas 24 hrs later the white matter is also involved. The decrease in choline acetyl-transferase and acetylcholinesterase activities in the gray matter parallels the impairment of complex IV (cytochrome c oxidase) of the respiratory chain and the presence of morphological alteration in neurons. The dramatic drop in the enzyme activities, observed 24 hrs after the induction of the severe trauma is clearly associated with the loss of cells.     

Across-family marker-assisted selection using selective genotyping strategies in dairy cattle breeding schemes

This study investigated the potential loss expected from marker-assisted selection (MAS) when only a proportion of animals are genotyped using several selective genotyping strategies. A population resembling a commercial dairy cattle population over 25 yr was simulated, and the most informative individuals for genotyping were identified among the potential breeding candidates (young bulls and bull-dams). Two strategies were used to identify the most informative animals. The first genotyping strategy was based on selecting individuals for genotyping with predicted total genetic effect [sum of the predicted quantitative trait locus (QTL) and polygenic effects] close to the truncation point for selection. The second strategy used an index that extended the previous strategy to include the variance due to segregation of the QTL in the parents. The 2 strategies for selective genotyping were applied at the 2 different genotyping levels and compared with random selection of candidates for genotyping and complete genotyping of the potential candidates. All selective genotyping strategies at the same proportion of genotyping showed similar cumulative genetic level. The frequency of the favorable QTL allele increased faster with more animals genotyped. Extra response in total genetic effect (polygenic and QTL) was not significantly different between genotyping all candidates (100%), 20%, and 50% genotyping (except for yr 13), but all MAS strategies resulted in significantly higher response than BLUP until yr 18. With 50% (20%) genotyping of candidates for selection within a population, 95% (89%) of maximum cumulative QTL response was achieved in yr 13. All MAS schemes resulted in a 19% decrease in the rate of inbreeding compared with the BLUP scheme. Therefore, it is possible to use selective genotyping in practical dairy cattle breeding and decrease the genotyping costs with a minimal loss of response compared with complete genotyping of the potential candidates.     

Detection of quantitative trait loci in Danish Holstein cattle affecting clinical mastitis, somatic cell score, udder conformation traits, and assessment of associated effects on milk yield

The aim of this study was to 1) detect QTL across the cattle genome that influence the incidence of clinical mastitis and somatic cell score (SCS) in Danish Holsteins, and 2) characterize these QTL for pleiotropy versus multiple linked quantitative trait loci (QTL) when chromosomal regions affecting clinical mastitis were also affecting other traits in the Danish udder health index or milk production traits. The chromosomes were scanned using a granddaughter design where markers were typed for 19 to 34 grandsire families and 1,373 to 2,042 sons. A total of 356 microsatellites covering all 29 autosomes were used in the scan. Among the across-family regression analyses, 16 showed chromosome-wide significance for the primary traits incidence of clinical mastitis in first (CM1), second (CM2), and third (CM3) lactations, and SCS. Regions of chromosomes 5, 6, 9, 11, 15, and 26 were found to affect CM and regions of chromosomes 5, 6, 8, 13, 22, 23, 24, and 25 affected SCS. Markers on chromosomes 6, 11, 15, and 26 can be used to perform marker-assisted selection on CM without a direct negative selection on milk yield, because no effects were detected on the milk traits. Comparing multi-trait models assuming either a pleiotropic QTL affecting 2 traits or 2 QTL each affecting 1 trait gave some evidence to distinguish between these models. For Bos taurus autosome 5, the most likely models were a pleiotropic QTL affecting CM2, CM3, and SCS, and a linked QTL affecting fat yield index. For Bos taurus autosome 9, the most likely model is a pleiotropic QTL affecting CM1 and CM2 at approximately 8 cM.     

The effect of gelation on statically and dynamically freeze-cast structures

Freeze-casting is a technique used to produce structures with anisotropic porosity in the form of well-defined microchannels throughout a sample. Here, this technique is used on the magnetocaloric ceramic La_0.66Ca_0.26Sr_0.07 Mn_1.05O₃. We show that a dynamic freezing profile, where the temperature is decreased continuously at −10 K/min, results in homogeneous, lamellar channels with widths of ∼15 µm, while static freezing, where the temperature is kept constant at 177 K, results in channels of increasing size away from the initial ice crystal nucleation site. The effect of gelation before freeze-casting is also investigated. Gelation inhibits ice crystal growth, which significantly changes the morphology by making channel cross sections less elongated, while additionally introducing more dendrites and ceramic bridges in the structure. The latter significantly dominates the flow path through the gelated structures, affecting the calculated tortuosity, which increases to τ ≈ 4 when compared to non-gelated samples where calculated tortuosities are in the range of ∼1.3 to ∼3. Finally, we present a systematic and automatic approach for evaluating channel and wall sizes and calculating tortuosities. This is based on analysis of images obtained by scanning electron microscopy using a continuous particle size distribution method and the TauFactor application in MATLAB^®.