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Results for “differential selection”

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PubMed1993

[Test of a quick differentiation of selected mycobacteria with pyrolytic gaseous chromatography].

The five mycobacterium strains H37Rv series 363, M. bovis (An5) series 250, M. kansasii series 377, M. intracellulare series 364, M. xenopi series 302 and BCG series 180291 were tested using pyrolytic gas chromatography method. After regeneration of lyophylisate, the strains were incubated using L-J medium in 37 degrees C for 2 to 6 weeks--the period that was necessary to obtain profuse growth. The bacterial mass obtained from the culture was collected in test-tubes and pyrolized after autoclave incubation and dry procedure. The CHROM 5 gas chromatograph together with FID detector was used for detecting the products of pyrolysis. The signal was transmitted from the detector to analog-digital converter A/C and registered by IBM PC/XT computer. 12-15 analysis of each strain were performed. Chromatograms of strains pyrolysis products were recorded as files to the hard disc. This way the standard data base was built. The pyrolysis products of tested strains were compared with data base using BAZCHRO program. E. coli JC 7623 was employed as a standard for comparison of chromatograms. The similarity of chromatograms was presented as percentage. The 85-95% of similarity was obtained as a result of comparison of the same Mycobacteria strains.

Chromatography, Gas↗
PubMed1997

Selective bipotential differentiation of mouse embryonic hepatoblasts in vitro.

A line of hepatic endoderm cells, hepatoblast cell line 3 (HBC-3), was derived from the liver diverticulum of the mouse on day 9.5 of gestation by culture on a mitomycin C treated STON+ feeder layer in a hepatoblast culture medium consisting of Dulbecco's modified Eagle's medium, nonessential amino acids, fetal calf serum, and beta-mercaptoethanol. This line, HBC-3, stains positively for alpha-fetoprotein, albumin, and cytokeratin 14 (CK-14), protein markers expressed by the embryonic liver diverticulum, indicating that HBC-3 cells retain an undifferentiated hepatoblast phenotype. HBC-3 cells acquire hepatocyte-like ultrastructural characteristics, including bile canaliculi, peroxisomes, and glycogen granules, when maintained in culture for 3 weeks without passage. Treatment with dimethylsulfoxide or sodium butyrate induces a rapid hepatocytic differentiation. The cells cease to express alpha-fetoprotein and CK-14, maintain albumin expression, and become positive for glucose-6-phosphatase activity (a profile consistent with differentiation along the hepatocyte lineage). On Matrigel, HBC-3 cells form elaborate ductular structures, which are positive for gamma-glutamyl transpeptidase and CK-14 and CK-19 and do not express detectable amounts of albumin, a phenotypic change consistent with differentiation along the bile ductular lineage. Thus, HBC-3 cells behave in culture as bipotential hepatoblasts and provide a model system to identify factors that regulate bipotential differentiation in the liver.

Animals↗
PubMed2007

Genetic control of alternative splicing in the TAP2 gene: possible implication in the genetics of type 1 diabetes.

The transporter 2, ATP-binding cassette, subfamily B (TAP2) is involved in the transport of antigenic peptides to HLA molecules. Coding TAP2 polymorphisms shows a strong association with type 1 diabetes, but it is not clear whether this association may be entirely due to linkage disequilibrium with HLA DR and DQ. Functionally, rat Tap2 nonsynonymous single-nucleotide polymorphisms (nsSNPs) confer differential selectivity for antigenic peptides, but this was not shown to be the case for human TAP2 nsSNPs. In the human, differential peptide selectivity is rather conferred by two splicing isoforms with alternative carboxy terminals. Here, we tested the hypothesis that alleles at the coding SNPs favor different splicing isoforms, thus determining peptide selectivity indirectly. This may be the basis for independent contribution to the type 1 diabetes association. In RNA from heterozygous lymphoblastoid lines, we measured the relative abundance of each SNP haplotype in each isoform. In isoform NM_000544, the G (Ala) allele at 665 Thr>Ala (rs241447) is more than twice as abundant as A (Thr) (GA = 2.2 +/- 0.4, P = 1.5 x 10(-4)), while isoform NM_018833 is derived almost exclusively from chromosomes carrying A (AG = 18.1 +/- 5.6, P = 2.04 x 10(-7)). In 889 Canadian children with type 1 diabetes, differential transmission of parental TAP2 alleles persisted (P = 0.011) when analysis was confined to chromosomes carrying only DQ*02 alleles, which mark a conserved DR-DQ haplotype, thus eliminating most of the variation at DR-DQ. Thus, we present evidence of TAP2 association with type 1 diabetes that is independent of HLA DR-DQ and describe a plausible functional mechanism based on allele dependence of splicing into isoforms known to have differential peptide selectivities.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2004

Reduced inflammatory pain in mice deficient in the differential screening-selected gene aberrative in neuroblastoma.

Differential screening-selected gene aberrative in neuroblastoma (Dan) protein is produced in small neurons of dorsal root ganglia. Thermal and mechanical allodynia and Fos expression in the spinal dorsal horn evoked by inflammation and neuropathic pain were investigated using Dan-deficient mice. Mice showed pain reactions induced by the introduction of complete Freund's adjuvant (CFA) into their hind paw (inflammatory pain model) and after sciatic nerve ligation (neuropathic pain model). In the inflammatory pain model, thermal and mechanical pain thresholds in Dan-deficient mice were significantly higher than those of wild-type mice. The number of Fos-immunoreactive cells in the dorsal horn during the inflammatory period was significantly less in Dan-deficient mice. However, in the neuropathic pain model, no differences in thermal hypersensitivity, mechanical allodynia, or the number of Fos-immunoreactive cells in the dorsal horn were observed between the mice. These data suggest that Dan may be a neuromodulator in inflammatory pain.

Animals↗
PubMed1999

Boswellic acid acetate induces differentiation and apoptosis in leukemia cell lines.

Boswellic acid acetate (BC-4), a compound isolated from the herb Boswellia carterii Birdw., can induce differentiation and apoptosis of leukemia cells. Based on cell morphology and NBT reduction, BC-4 induced monocytic differentiation of myeloid leukemia HL-60, U937 and ML-1 cells at a dose under 12.5 microg/ml (24.2 microM). BC-4 was a potent inducer, with 90% of the cells showing morphologic changes and 80-90% of the cells showing NBT reduction. Specific and non-specific esterase were also increased by BC-4. Based on benzidine staining assay, BC-4 failed to induce erythroid leukemia DS-19 and K562 cells differentiation. In contrast to its selective differentiation effect, BC-4 strongly inhibited growth of all cell lines tested. The growth inhibition effect was dose- and time-dependent. In HL-60 cells, 20 microg/ml (38.8 microM) of BC-4 decreased viable cell number by 60% at 24 h, whereas at 3 days there was virtually no viable cells. Morphologic and DNA fragmentation analysis proved that BC-4 induced cell apoptosis. The dual apoptotic and differentiation effects of BC-4 suggest that it may be a powerful agent in the treatment of leukemia.

Antineoplastic Agents, Phytogenic↗
PubMed2004

Chromosomal polymorphism, morphometric traits and mating success in Leptysma argentina Bruner (Orthoptera).

The South-American species Leptysma argentina Bruner is polymorphic for a centric fusion between chromosomal pairs 3 and 6 (fusion 3/6). Cytogenetic and morphological studies revealed that fusion 3/6 significantly increases some morphometric variables in males. A selection components study showed that the fusion is positively selected for longevity, the direct effect being exerted on thorax height. Moreover, a unisexual approach revealed that sexual male selection acts by increasing third femur length. In the present study the effect of fusion 3/6 on morphometric variables and the effect of body size and karyotype on mating success in both males and females were analysed through a bisexual approach. Total body length (TL) and third femur length (FL) were significantly larger amongst the fusion carrier females. Besides, the largest females and the carriers of the fusion have increased mating success. The selection differential suggests that directional sexual selection favours the females with increased TL and fusion dosage; however, the selection gradient revealed that none of the variables here analysed is a direct target of sexual selection. The male sexual selection study agrees with previous results, showing the importance of the third pair of legs in male mating success among grasshoppers.

Animals↗
PubMed2000

Multivariate analysis of male mating success on morphometric traits and chromosome dosage in the grasshopper Sinipta dalmani.

Sinipta dalmani is a South American grasshopper that is chromosomally polymorphic for a pericentric inversion in the M4 pair. The inversion affects morphology, showing a negative average effect on body size. In the present work, male mating success was analysed in competition cages and possible correlations examined between this fitness component, body size and inversion polymorphism. The outcome of the study revealed that mated males were larger and had lower inversion dosage than unmated ones. The analysis of standardized selection differentials (S') demonstrated that directional selection operated on chromosome dosage and 3rd tibia, 3rd femur, thorax and tegmina lengths. The analysis of karyotype frequencies showed that mated males had a higher frequency of the standard homozygote karyotype. The analysis of selection gradient (beta') and the transformed logistic regression (alpha) showed an important effect of selection on 3rd tibia length. Identical conclusions were obtained when linear and logistic multiple regression were performed on the first three components of PCA analyses. Our results indicate that differences in some body size-related traits are determined by the karyotype, and that of these length of 3rd tibia provides the greatest contribution to variation in fitness. The selective effects detected on chromosome dosage and the other morphological traits may be considered as indirect ones caused by correlated effects.

Animals↗
PubMed1999

Direct and correlated response to divergent selection for serum immunoglobulin M and G levels in chickens.

Two pairs of chicken lines were divergently selected for serum immunoglobulin M and G levels at 10 wk of age to examine the effect of selection on direct and correlated traits. After three generations of selection, the lines were tested for their ability of antibody production against SRBC, a T cell dependent antigen. At 14 and 17 wk of age, the lines were immunized intravenously with 1 mL of 5% SRBC solution. Blood samples were collected at 7 and 14 d of post primary immunization (PPI) and post secondary immunization (PSI). Selection was effective (P < 0.01) in changing the serum immunoglobulin M levels. The G levels were changed in a downward direction initially in the high line. The differences between the high immunoglobulin M (HIM) and low immunoglobulin M (LIM) lines as well as high immunoglobulin G (HIG) and low immunoglobulin G (LIG) lines became larger during the course of selection. Selection differentials varied considerably during the selection, but the selection response was almost constant. Realized heritability was relatively high, ranging from 0.58 to 0.66 and from 0.40 to 0.60 for the IgM and IgG selected lines, respectively. Total antibody titers to SRBC differed significantly (P < 0.01) between the HIM and LIM lines at 7 and 14 d PPI, and 7 d PSI. The HIM line also produced significantly higher mercaptoethanol resistant antibody titers to SRBC than the LIM line at 7 and 14 d PPI and PSI. The LIG line had significantly higher total antibody titers to SRBC than the HIG line at both 7 and 14 d of PPI and PSI. From these results, it is suggested that selection of chickens on the basis of serum immunoglobulin isotypes may change antibody producing cells as well as other immunocompetent cells that modulate the immune response of the selected lines.

Animals↗
PubMed2001

Sexual selection of multiple handicaps in the red-collared widowbird: female choice of tail length but not carotenoid display.

Although sexual selection through female choice explains exaggerated male ornaments in many species, the evolution of the multicomponent nature of most sexual displays remains poorly understood. Theoretical models suggest that handicap signaling should converge on a single most informative quality indicator, whereas additional signals are more likely to be arbitrary Fisherian traits, amplifiers, or exploitations of receiver psychology. Male nuptial plumage in the highly polygynous red-collared widowbird (Euplectes ardens) comprises two of the commonly advocated quality advertisements (handicaps) in birds: a long graduated tail and red carotenoid coloration. Here we use multivariate selection analysis to investigate female choice in relation to male tail length, color (reflectance) of the collar, other aspects of morphology, ectoparasite load, display rate, and territory quality. The order and total number of active nests obtained are used as measures of male reproductive success. We demonstrate a strong female preference and net sexual selection for long tails, but marginal or no effects of color, morphology, or territory quality. Tail length explained 47% of male reproductive success, an unusually strong fitness effect of natural ornament variation. Fluctuating tail asymmetry was unrelated to tail length, and had no impact on mating success. For the red collar, there was negative net selection on collar area, presumably via its negative relationship with tail length. None of the color variables (hue, chroma, and brightness) had significant selection differentials, but a partial effect (selection gradient) of chroma might represent a color preference when tail length is controlled for. We suggest that the red collar functions in male agonistic interactions, which has been strongly supported by subsequent work. Thus, female choice targets only one handicap, extreme tail elongation, disregarding or even selecting against the carotenoid display. We discuss whether long tails might be better indicators of genetic quality than carotenoid pigmentation. As regards the evolution of multiple ornaments, we propose that multiple handicap signaling is stable not because of multiple messages but because of multiple receivers, in this case females and males.

Animals↗