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Results for “pure lines”

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At least 19 recordsLinked to original sources
PubMed1988

Small cell lung cancer cell lines: pure and variant types can be distinguished by their extracellular matrix synthesis.

Variant subclasses of cell lines derived from small cell lung cancers have previously been characterized, having distinctive biochemical, morphological and growth properties compared to the classic lines. Both types of small cell lung cancer express features suggesting that they are derived from neuroectodermal cells. We compared the capacity of these two types of lung cancer cell lines to synthesize the extracellular matrix glycoproteins, fibronectin and laminin, and also analysed a few other non-small cell lung cancer lines, as controls. We found that the cell lines of the pure type did not produce laminin or fibronectin, whereas the cell lines of the variant type synthesized laminin, and the non-small cell lung cancer lines produced either laminin or fibronectin. These findings suggest that the variant form of small cell lung cancer may be derived from a primitive neuroectodermal cell, with both neural and epithelial features, whereas the classic type is derived from a more mature cell with predominantly neuronal features. The differences in extracellular matrix synthesis, and laminin in particular, may explain some of the in vitro and in vivo characteristics of the tumour.

Carcinoma, Non-Small-Cell Lung↗
PubMed1986

Genetic and maternal effects on pig weights, growth and probe backfat in diallel crosses of high- and low-fat lines of swine.

Two Duroc and two Yorkshire lines of pigs that had been selected at Beltsville Agricultural Research Center for 12 and 10 generations, respectively, for either thinner or thicker backfat were mated to produce all possible pure lines and reciprocal crosses in 1967, 1969 and 1970. Data for littermate gilts and barrows from 136 litters were analyzed to estimate genetic and maternal influence on individual pig weights at birth, 21 d, 56 d and 140 d of age; age at 79.4 kg; average backfat thickness at 79.4 kg and postweaning average daily gain (56 d to 79.4 kg). Pure-line gilts differed among breed-lines (P less than .05 or P less than .01) for all traits except weight at 56 d. Gilts of the two low-fat lines were heavier than gilts of the two high-fat lines through 56 d of age, but Yorkshire low-fat gilts were lightest at 140 d, were oldest at 79.4 kg and had the slowest daily gain, in addition to the least backfat. The Duroc low-fat line gilts were heaviest at 140 d, youngest at 79.4 kg and were second thinnest in backfat. Among pure-line barrows, the low-fat lines were heaviest at birth, at 21 d and at 140 d and were thinnest in backfat. Line-cross gilts were heavier than pure-line gilts at all four ages, were younger at 79.4 kg and higher in daily gain. Among barrows, line crosses were heavier in all weights except at 21 d, were younger at 79.4 kg and were higher in daily gain than pure lines. Differences between pure lines and line crosses in backfat were not significant for either sex. Heterosis varied from 6.5 to 16.7% among weights and growth traits. Pigs of both sexes differed among breed-lines in general combining ability for all traits except 21-d weight, and differed in maternal ability for weights through 56 d and for backfat. Specific combining ability (SCA) was significant only for intra-breed crosses for weight at 21 d, and for inter-breed, intra-line crosses for 21- and 56-d weights and for age at 79.4 kg among gilts, with no significant effects in SCA for any trait among barrows. General combining ability was not correlated with maternal effects for any trait except 21-d weight, for which they were positively correlated (r greater than .80).

Adipose Tissue↗
PubMed1976

The selection of somatic cell hybrids between human lymphoma cell lines.

Somatic cell hybrids have been selected between three pairs of established human lymphoid cell lines producing pure lines of proliferating hybrid cells: Raji/Namalwa, Raji/Daudi, and Raji/BJAB. The hybrid cell lines have been characterized with respect to isozyme pattern, volume, and karyotype.

Cell Division↗
PubMed2025

Speed breeding: protocols, application and achievements.

One of the limiting factors in breeding and genetic research is the time required to develop pure lines. This is due, on the one hand, to the prolonged vegetative period of a single generation and, on the other hand, to the specifics of inbreeding, which typically requires 4-6 consecutive generations of self-pollination in plant material. Researchers have always sought approaches that enable the rapid development of homozygous plant lines. Consequently, methods such as greenhouse cultivation during the autumn-winter period, single-seed descent, shuttle breeding, embryo culture, and doubled haploid technology have been introduced into practice. All these methods have both advantages and limitations. One of the latest approaches facilitating a significant reduction in the vegetative period of plants is speed breeding (SB). This method is based on the application of factors that shorten the time from sowing to flowering, as well as techniques that accelerate the generative phase of development and overcome postharvest dormancy. This review provides a comprehensive list and characterization of all factors that influence the efficiency of speed breeding to varying degrees. Among the factors discussed that reduce the sowing-to-flowering period are photoperiod, light sources, spectral composition and light intensity, temperature, carbon dioxide levels, vernalization, mineral nutrition, substrate volume, mechanical shoot removal, and the use of plant growth regulators. To shorten the generative phase, the review summarizes the application of embryo culture and forced desiccation of immature seeds, along with methods to overcome postharvest dormancy. Additionally, applications of genetic approaches and genetic engineering for shortening generation time in speed breeding are described. The review also consolidates detailed protocols for approximately thirty crops. The high efficiency of speed breeding in reducing both the vegetative period per generation and the time required to develop pure lines has led to its increasing adoption in various research fields. This review highlights the application of speed breeding for hybridization and pure line development, introgression of target alleles, and genomic selection. A list of phenotypic traits exhibiting high correlation between controlled-environment and field conditions is provided.

accelerated flowering↗
PubMed1988

Fat deposition in a broiler sire strain. 4. Performance of broiler progeny of four differently selected sire lines.

Cocks from four lines selected for a low amount of abdominal fat (AF), a favorable feed conversion ratio (FC), and high body weight after restricted (GR) or ad libitum (GL) feeding were mated to commercial broiler breeder hens. A total of 3,600 broiler progeny in three hatches from these matings was reared by line in litter pens. At 41 days of age GR and GL line progeny had significantly heavier body weights, poorer feed conversion ratio, and higher percentages of abdominal fat than AF and FC line progeny. At comparable body weights (AF, 1,893; FC 1,918; GR, 1,848; and GL, 1,897 g) feed conversion was most favorable for FC line progeny (1.72), AF and GL line progeny did not differ (1.77), and GR line progeny had the poorest feed conversion ratios (1.79). The AF line progeny had the lowest percentage abdominal fat (1.88%), followed by FC line progeny (2.20%), GL line progeny (2.91%), and GR line progeny (3.10%). As in the pure lines, selection for body weight after restricted feeding was not effective in obtaining leaner and more efficient chickens. When compared with differences between pure lines, results of the broiler progeny matings indicate that body weight, feed conversion, and percentage abdominal fat are inherited largely in an additive manner.

Abdomen↗
PubMed1991

Inbreeding and heterosis effects on quantitative traits in a White Leghorn population under long-term reciprocal recurrent selection.

1. Inbreeding and heterosis effects for quantitative traits were estimated in two White Leghorn lines selected with reciprocal recurrent selection (RRS) since 1950. 2. Pedigreed progeny were produced from full-sib, half-sib and unrelated pure line as well as reciprocal cross line matings to estimate inbreeding and heterosis effects "within sires". 3. Inbreeding effects estimated as linear regressions agreed well with estimates considering inbreeding as fixed effect. The inbreeding depression per 10% inbreeding was highest for hatchability (6-7%), intermediate for production-related traits (3%), and about 1% for shell quality, body weight and egg weight. 4. Heterosis effects were estimated by comparing pure line and cross line progeny of the same sires. 5. Results indicate considerably less heterosis for egg production than found earlier, which is interpreted as a consequence of pure line selection.

Animals↗
PubMed1990

Collagen, proteoglycan and hyaluronidase activity in cultures from normal and scoliotic chicken fibroblasts.

Connective tissue matrix components were investigated using skin fibroblasts from normal or inbred scoliotic lines of chickens. Specifically, the fibroblasts were obtained from either an isogenic line or a backcross, derived by crossing the isogenic line with a pure line of scoliotic birds. From the backcross, both affected (35-45%) and non-affected (55-65%) progeny were produced. The affected birds had spinal curves greater than 20 degrees. Several abnormalities of connective tissue were observed when cells from scoliotic chicks were grown in culture: increased collagen extractability, decreased aggregatability of proteoglycans under associative conditions and lower than normal levels of hyaluronic acid. There was also less collagen deposited in the cell layer with proportionately increased amounts of collagen secreted into the culture media by cells from scoliotic versus normal chick fibroblasts. Values for collagen matrix stability, as estimated by extractability and net deposition, were intermediate for cells from the backcrossed, but non-affected, birds. Moreover, hyaluronidase, an enzyme that degrades hyaluronic acid, was abnormally elevated in the fibroblast cultures from scoliotic chicks. It is proposed that the increase in hyaluronidase contributes to the abnormalities observed in extracellular matrix components and may be a factor in the expression of scoliosis in susceptible birds.

Animals↗
PubMed1976

Septal lines in pure right heart failure.

Two adult patients are described with pure right heart failure and chronically elevated systemic venous pressure. Neither patient had evidence of pulmonary venous hypertension, but both had septal lines. This unusual finding may be the result of impaired centripetal lymph flow in the lungs due to obstruction of the drainage of the thoracic duct by raised systemic venous pressure.

Adolescent↗
PubMed1976

Sex difference in mortality rates of Leghorn-Red reciprocal crosses.

Mortality rates among White Leghorn-Rhode Island Red pure-line and reciprocal cross adult female progeny were recorded for 8 years. The mortality rate among progeny of White Leghorn males exceeded that of the progeny of Rhode Island Red males in both pure-line and crossbreds. White Leghorn X Rhode Island Red crossbred progeny had the highest mortality rate. In a second phase of the study, a comparison was made between mortality rates of male and female progeny of White Leghorn-Rhode Island Red reciprocal crosses. Rate of loss was significantly lower in males than in females but did not differ between crosses. These results support a conclusion that sex linkage is a major factor in differential mortality rates between progeny of White Longhorn-heavy breed reciprocal crosses.

Animals↗
PubMed1992

Dependence of acetazolamide teratogenesis on fetal and not maternal genotypes.

This study assesses the relative contributions of dam and conceptus to sensitivity to acetazolamide teratogenesis in an in vivo mouse model. Reciprocal F1 outcrosses were made between mice resistant to the teratogenic effects of acetazolamide (SWV) and the susceptible C57BL/6JBk line. Female F1 progeny were backcrossed either to C57BL or to SWV males. The F1 outcross resulted in identical fetuses developing in genetically different uterine environments. In the backcrosses, genetically identical hybrid dams were gestating genetically different populations of segregating fetuses. In both F1 outcrosses and backcrosses, as well as in pure-line controls, dams were treated on day 9 of gestation by subcutaneous injection of acetazolamide (ACZM) at a dose level of 1500 mg/kg, or identical volume of the vehicle. The principal abnormality seen was right front limb ectrodactyly. Among pure-line matings, SWV produced no ectrodactyly, but 68% of C57BL showed this defect. Only two cases were seen in outcross of C57BL females to SWV males, and one litter produced three ectrodactylous fetuses in the reciprocal cross. A highly significant increase in ectrodactyly was seen in treated backcrosses to C57BL relative to backcrosses to SWV. Thus, a litter in which most of the genes segregating are from a susceptible line will show major increases in susceptibility, despite being in a heterotic and somewhat resistant uterine environment, whereas the susceptible C57BL uterine environment does not result in significant abnormality in heterozygous resistant fetuses. These results unequivocally demonstrate that it is the genotype of the conceptus, and not the genotype of the dam, nor heterosis, that determines sensitivity to acetazolamide teratogenesis. They further suggest that this genetic approach may be useful in determining the relative contribution of dam and conceptus for other teratogens.

Abnormalities, Drug-Induced↗
PubMedDate not supplied

Surface and cloacal temperatures in chicks of different genetic stocks given an Escherichia coli inoculation.

The effect of Escherichia coli on surface and cloacal temperatures was assessed in pure line and hybrid chicks from both white rock and leghorn stocks. Body weights, surface temperatures, and cloacal temperatures were obtained from 2 to 30 days of age. Two groups of chicks, one 8 days and the other 30 days of age, were inoculated via the caudal thoracic air sac with E. coli, and effects were quantified as changes in body weight, surface and cloacal temperatures, lesions on heart and air sacs, and mortality. Pure line white rock chicks had the highest mortality from the E. coli inoculation and proportionally lost the most weight over the 48-hr period immediately following inoculation. Chicks inoculated at 30 days of age were affected more severely than those inoculated at 8 days. Surface and cloacal temperatures were not reliable predictors of resistance to an E. coli inoculation.

Aging↗
PubMed1991

Long-term goose breeding for egg production and crammed liver weight.

1. Results of an 8-year (1981 to 1988) period of breeding geese for egg production and crammed liver weight, including phenotypic and/or genetic parameters for various traits (1982 to 1985), as well as line tests (1987 to 1988), are summarised for two lines. 2. The regressed annual genetic gains over years were 2.7 eggs and 30.8 g crammed liver. However, there was a decline in the rate of genetic progress after 4 years of selection. 3. Heritability estimates were found to be relatively high for most traits, whereas phenotypic and genetic correlation coefficients between traits were rather low, as would be expected from lines not previously subjected to an intense selection programme. 4. Phenotypic correlation coefficients between part-period records and full-period egg production, suggest that 3-month (October to December) records may be adequate to identify most of the best first-year layers. However, sexual maturity should be treated as a separate trait. 5. The cross between the 'Grey' (male) line, superior in crammed liver weight, and the 'White' (female) line, excelling in egg production, seems to be superior to the pure lines, in a fully-integrated enterprise.

Analysis of Variance↗
PubMed1987

Effects of selection for high and low plasma glucose concentration in chickens.

1. Two lines of broilers exhibiting low (LG) or high (HG) plasma glucose concentrations were selected from a pure line of White Rock chickens. 2. Realised heritabilities were close to 0.25 in both lines. 3. The LG line was significantly fatter than the HG line; this difference was more pronounced in females than in males. 4. Food was utilised less efficiently by the LG line than by the HG one.

Animals↗