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PubMed2004

A Paramecium tetraurelia mutant that has long autogamy immaturity period and short clonal life span.

We have isolated an unprecedented mutant of Paramecium tetraurelia that has a long immaturity period until autogamy. This mutant stock, d4-RK, screened for 0% autogamy at the age of 27 fissions, began to undergo autogamy around the age of 50 fissions in some clones and underwent autogamy scarcely even after the age of 100 fissions in others. d4-RK expressed its mutant phenotype at 25 degrees C, but resembled the wild-type phenotype at 32 degrees C. Genetic analyses indicated that a single recessive gene, named rie (remote immaturity exit), was responsible for the mutant phenotype. This is the first report to show a gene that elongates the time to sexual maturation in unicellular organisms. The clonal life span was shorter and fission rate was lower in the rie mutant than in the wild-type, both at 25 degrees C and 32 degrees C. Even in the fourth autogamous generation following the third backcross to the wild-type, the progeny with the elongated autogamy immaturity period still had a short clonal life span and low fission rate, while those with the wild-type phenotype in autogamy immaturity period showed the wild-type phenotypes in clonal life span and fission rate, too.

Animals↗

PubMed2005

A new mutation in the timing of autogamy in Paramecium tetraurelia.

We have isolated a new type of Paramecium tetraurelia mutant, named rie-2, that has a long immaturity period until autogamy. We previously isolated such an autogamy mutant, designated rie-1. These two mutants had some additional common features such as dependence of the occurrence of autogamy on the temperature, involvement of a single recessive gene, lower fission rate and shorter clonal life span. However, rie-2 was considered a new type mutant distinguishable from rie-1 because of their different natures of temperature sensitivity. First, the temperature at which they resembled the wild-type phenotype was low (19 degrees C) in rie-2, although it was high (32 degrees C) in rie-1. Second, the clonal life span of rie-2 at 25 degrees C was similar to that of the wild-type, but it was extremely shorter at 32 degrees C than at 25 degrees C, although it was similarly shorter at both temperatures in rie-1. Third, the difference of the fission rate between mutant and wild-type was greater at 32 degrees C than at 25 degrees C in rie-2, although it was similar at both temperatures in rie-1. This report shows that a gene mutation to elongate the period until sexual maturation does not necessarily assure the long life span.

Animals↗

PubMed1981

Cancers of the breast and female genital system: search for recessive genetic factors through analysis of human isolate.

To investigate the importance of recessive genes in female breast and genital cancers, we have conducted investigations in the Hutterites, a highly inbred genetic isolate in North America. The homogeneous life style of this group, which lives on communal farms, also facilitates distinction between shared environmental and genetic factors. We ascertained 177 cases of cancer (all organ systems) through Canadian and United States cancer registries, field trips, and searches of death certificates. Breast cancer and endometrial cancer mortalities were those expected for 1970 United States whites, but no deaths due to squamous cervical carcinoma were ascertained in this monogamous population. Inbreeding coefficients (F) for cases were higher than means for matched controls for each of the four cases of breast cancers that occurred in younger women (less than 45 years of age), for four of five cases of endometrial cancer, and for the single cases of uterine leiomyosarcoma, dysgerminoma, and ovarian adenocarcinoma. By contrast, in cases of breast cancer that occurred in women 45 years of age or older, only four of 15 F's were above those for controls. There is a significant difference between the two breast cancer age groups with respect to the likelihood that the F of cases was higher than the F of controls (chi 2 = 6.99, p less than 0.01). However, grouping cases by type, none of the F distributions were significantly different from those of their matched controls. These preliminary genetic investigations thus conform certain concepts concerning breast and female genital cancer but also suggest the desirability of further studies to elucidate the role of genetic factors in premenopausal breast cancer.

Adult↗

PubMed1979

Three siblings with premature gonadal failure.

Of a brother and two sisters with infertility, one female sibling was found to be mosaic for Turner's syndrome. The brother and the other sister, of average intelligence, were phenotypically normal, with no dysmorphic features or ambiguous genitalia, but both showed hypergonadotropic hypogonadism. It is suggested that the basic defect in these two siblings is the same and is of genetic origin. As the parents were consanguineous, the defect is most likely due to an autosomal recessive gene.

Female↗

PubMedDate not supplied

Polygenic control of the expression of biological activities of an antitumor polysaccharide, lentinan.

Genetic studies were carried out on two in vivo responses of lentinan, delayed type-acute phase responses (DT-APR) and vascular dilation and hemorrhage (VDH). Linkage analyses showed that DT-APR was controlled by two recessive genes, ltnr1 and ltnr2, which were mapped on chromosome 3 and 11, respectively. VDH was also found to be controlled by polygenes. One dominant major gene, Ltnr3, and three dominant minor genes, Ltnr4, Ltnr5, and Ltnr6, were mapped on chromosomes 6, 9, 15 and 16, respectively.

Acute-Phase Reaction↗

PubMed1997

Hearing loss in the RBF/DnJ mouse, a proposed animal model of Usher syndrome type IIa.

The Usher syndromes (US) are a group of inherited disorders that feature autosomal recessive neurosensory hearing loss or deafness with retinitis pigmentosa (RP). Moderate to severe non-progressive high frequency hearing loss with RP and normal vestibular function describes Usher syndrome type IIa, which has been localized to 1q41. Severe retinal degeneration in the inbred mouse strain RBF/DnJ is caused by rd3, a recessive gene located on mouse chromosome 1 distal to akp1 in a region which is orthologous to human 1q32-q42. We evaluated rd3 as a candidate for orthology with USH2A by first reducing and refining the relatively broad region in which rd3 is thought to reside. DNA of offspring from an RBF/DnJ x MOLF/Ei backcross was genotyped with PCR markers closely flanking the predicted location of rd3. Our haplotype analysis re-positioned rd3 to a 3.6 cM region between markers D1Mit273 (cen) and D1Mit209 (tel), consistent with the expected position of an USH2A murine orthologue. Consequently, rd3 is a positional candidate for Usher type IIa. Next we assessed the rd3/rd3 audiological phenotype to see how closely it paralleled that of Usher IIa. Audiological evaluation of mice at various ages revealed evidence of high frequency progressive hearing loss, previously unreported in the RBF/DnJ strain. However, this newly discovered hearing deficit was observed to be inherited independently of rd3, establishing that a completely different gene is responsible.

Animals↗

PubMed1984

A genetic study of the Fukuyama type congenital muscular dystrophy.

A genetic study was carried out on 153 families with 186 Fukuyama type congenital progressive muscular dystrophy (FCMD) patients. Consanguineous marriage of parents was found in 41 families (26.80%). Inbreeding coefficients in the patients was 10 times as high as that of the general population. Both sexes were almost equally affected (M:F = 1.1:1.0). No single parent of the patients was affected. Recurrence among siblings was frequent (9 out of 41 siblings in offspring of related parents and 18 out of 110 siblings in offspring of unrelated parents were affected. The segregation ratio was 23.91-27.08% in offspring of related parents, 20.00-22.94% in offspring of unrelated parents, these values being not significantly different from the 25% expected from the assumption of autosomal recessive mode of inheritance. In the sample two twin pairs were included, of which one male isosexual pair was concordant. Sporadic cases were not significantly more numerous than expected. All these data indicate that the disorder is caused by homozygosity of an autosomal recessive gene. Frequency of the gene was estimated to be 5.2-9.7 X 10(-3) and frequency of the patients 6.9-11.9 X 10(-5). Mutation rate was estimated to be 6.9-11.9 X 10(-5).

Adolescent↗

PubMed1991

Growth hormone and insulin-like growth factor-I measurements in high growth (hg) mice.

Effects of a recessive gene causing high growth (hg) were studied on two major components of the growth axis in mice. Plasma and pituitary levels of growth hormone and plasma levels of insulin-like growth factor I (IGF-I) were measured in three lines homozygous for hg, each compared with a control line of alike genetic background but wild type for the hg locus (Hg). Line Gh (hghg) and line GH (HgHg) are from a line which had undergone long-term selection for high postweaning weight gain; line Ch (hghg) and line CH (HgHg) were extracted from the second backcross of Gh to C57BL/6J; line L54 (hghg) was from the sixth backcross to C57BL/6J (B6) (HgHg). Pituitary GH levels and plasma IGF-I levels were measured in both sexes at 3, 4.5, 6 and 9 wk of age. Plasma growth hormone was measured in 8- to 12-wk-old males at hourly intervals from 08.00 to 17.00. Body weight in lines homozygous for hg at 6 and 9 wk of age was 10-30% greater than in control lines. The ontogeny of this increased growth depended on genetic background. Pituitary growth hormone content was 52% lower in the two hghg lines measured (lines Ch and Gh) than in control lines at 4.5, 6 and 9 wk. Plasma growth hormone levels were also much lower in hg mice, with values only 20-30% of those in their respective controls. hg lines showed consistently low plasma growth hormone levels throughout the 9 hr sampling period, while control lines expressed the characteristic pulsatile hormone secretion.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1995

Genetic control of the CD4/CD8 T-cell ratio in humans.

We studied the genetic pattern of inheritance of the ratio between circulating CD4+ and CD8+ T lymphocytes in a population of healthy donors. The distribution of the CD4/CD8 ratio in males and females was significantly different and was significantly affected by age. In 46 randomly selected families, the parental CD4/CD8 ratio significantly influenced the ratio in offspring. Complex segregation analysis of the data rejected the non-genetic hypothesis; among the genetic models tested, a major recessive gene with a polygenic component and random environmental effects was the most parsimonious model. These findings indicate that the ratio of CD4+ and CD8+ T cells is genetically controlled in humans.

Adult↗

PubMed1971

Carbohydrate metabolism of the isolated perfused liver of normal and genetically obese--hyperglycaemic (ob-ob) mice.

1. A technique for perfusion of the mouse liver has been developed, and aspects of carbohydrate metabolism have been investigated in the perfused liver of normal and genetically obese mice, homozygous for the recessive gene ob. 2. Rates of gluconeogenesis in perfused mouse liver were faster than those reported for slices of mouse liver, particularly from lactate and pyruvate. 3. The rate of glycogen breakdown to glucose, but not to lactate, was faster in liver from fed obese mice. 4. The capacity for glycogen synthesis from glucose was enhanced in liver from 20h-starved obese mice. 5. The capacity for gluconeogenesis from a number of substrates was not significantly altered in livers from fed or starved obese mice when compared with that of lean mice. 6. These results suggest that the liver contributes to the hyperglycaemia of the obese mice by increased glycogenolysis, and that liver glycogen in obese mice is maintained by synthesis from dietary glucose.

Alanine↗

PubMed1998

Evaluation of a restricted likelihood ratio test for mapping quantitative trait loci with extreme discordant sib pairs.

Risch and Zhang recently proposed to use extreme discordant sib pairs for mapping quantitative trait loci. Here, it is shown that the set of genetically possible distributions of the number of marker alleles in such sib-pairs is described by two inequalities. Thus, a likelihood ratio test analogous to Holmans's possible triangle test for affected sib pairs can be defined. The performance of this test is compared to the mean test considered by Risch and Zhang. For most of the genetic models considered, the mean test is slightly more powerful than the restricted likelihood ratio test. However, for models with a rare recessive gene (or equivalently a common dominant gene), the restricted likelihood ratio test is much more powerful.

Alleles↗

PubMed1984

The development of congenital hydrocephalus in the mouse.

The development of hydrocephalus has been investigated in a strain of mice with an autosomal recessive gene for hydrocephalus. The hydrocephalus is apparent in histological sections by 1 day after birth as a dilatation of the lateral ventricles and cavitation of the surrounding brain. Infusion experiments show that the flow pathway out of the ventricles is obstructed in 4 day hydrocephalic animals or older but not in newborn animals. The resistance to absorption of the cerebrospinal fluid from the lateral ventricles is high in normal animals at 1-2 days after birth and it falls to adult values at 14 days. Resistance from the cisterna magna is lower than from the lateral ventricles in animals less than 14 days suggesting that, in the first week or two after birth, there is a resistance in the flow pathway through the ventricular system. In hydrocephalic animals the resistance of the flow pathway was higher than normal. There was no defect in the capacity for fluid absorption from the subarachnoid space in hydrocephalic animals.

Animals↗

PubMed1999

Evaluation of inner ear histology and auditory brainstem response in Wriggle Mouse Sagami.

Wriggle Mouse Sagami (WMS) is a spontaneous mutant strain with neuroepithelial defects. These animals are characterized by abnormal movements linked to an autosomal recessive gene. To determine the association between inner ear histology and hearing ability, we assayed these characteristics in mice homozygous and heterozygous for the mutation, as well as in wild-type animals. In homozygotes, the cochlea and saccule degenerated 3 months after birth. Beginning at 3 months of age, and progressing in an age-dependent manner, the organ of Corti disappeared and the number of spiral ganglion cells decreased, starting at the basal turn and moving toward the apical turn. The sensory epithelium became atrophic in the saccule. Three-month-old heterozygotes demonstrated degeneration in the cochlea, not in the saccule. No obvious auditory brainstem evoked response (ABR) was observed at any frequency in homozygotes aged 1 month and older. In contrast, the heterozygotes retained some hearing acuity until the age of 1 month, after which they became deaf. These findings suggest that WMS mice may provide a good model that will be useful in identifying deafness genes in humans.

Animals↗

PubMed1983

Inheritance of brown-eye and colourless-eye in the mosquito Aedes aegypti.

An autosomal recessive gene bw (probably closely linked to y on chromosome 2) gives a brown eye colour. When this gene and the sex-linked gene re (red-eye) are both homozygous, a colourless-eye results. Brown-eye shows good viability and penetrance, and it has been maintained as a pure stock. Colourless-eye shows 87% penetrance in both sexes, and the females are low in viability and fertility. A colourless-eye stock has been maintained by crossing colourless-eyed males to their heterozygous red-eyed sibs. Crosses indicated no allelism between bw and ru (rust-eye), nor with w (white-eye). However some complementation between bw and w was indicated.

Aedes↗

PubMed2005

Familial risk for lung cancer by histology and age of onset: evidence for recessive inheritance.

The authors used the Swedish Family-Cancer Database to search for evidence for a genetic predisposition in lung cancer. Familial risks in offspring were increased for all lung cancer to 1.77 when a parent was affected with any lung cancers; the comparable risk among siblings was 2.15. At young age, risks between siblings were higher than those between offspring and parents for all histological types of lung cancer. The present data suggest that 1.7% of lung cancers up to age 68 years are heritable and probably due to a high-penetrant recessive gene or genes that predispose to tobacco carcinogens.

Adolescent↗

PubMed2006

Congenital hypothyroidism in Peters plus syndrome.

Peters plus syndrome is a multiple malformation syndrome characterized by a combination of Peters anomaly of the eye and other extraocular defects, including short-limb dwarfism, a thin upper lip, hypoplastic columella, and a round face. Two unrelated children with the typical features of Peters plus syndrome and hypothyroidism have been previously reported in medical literature. Herein, we report a male patient who exhibited the Peters plus syndrome phenotype as well as hypothyroidism and provide further evidence that hypothyroidism may represent an under-recognized feature of Peters plus syndrome. The consanguinity of the parents in the present case supports, but does not confirm, the notion that a homozygous defect in a single autosomal recessive gene might be responsible for the normal morphogenesis of both the anterior chamber and the thyroid gland.

Abnormalities, Multiple↗

PubMed1971

Defects in hematopoietic differentiation in NZB and NZC mice.

Hematopoietic stem cell activity in inbred NZB and NZC mice has been determined by transplantation and endogenous spleen colony assays. Whereas NZB mice show normal colony-forming unit (CFU) activity in the transplantation assay, they show markedly elevated endogenous CFU. NZC mice also show this markedly elevated endogenous CFU activity, but in the transplantation assay show only about 5-10% of normal CFU counts. When NZC stem cells are tested for CFU activity in irradiated recipients of the H-2(d) type, almost normal colony numbers occur. NZB stem cells however also cannot form colonies in NZC mice. These results suggest that NZC mice have a defect in the micro-environment of the spleen which renders them incapable of allowing transplanted CFU to form colonies. Genetic analysis of both the NZC defect as a CFU recipient, and the elevated endogenous count in NZB and NZC, shows that both are controlled by single recessive genes which are not linked to either coat color, agouti, H-2 or Ig loci. Of even more relevance is the finding that these hematopoietic abnormalities are not linked to the genes involved in controlling autoantibody formation to red cells in the NZB mice. These mice therefore appear to show two distinct hematopoietic abnormalities, the analysis of which may be of considerable value in understanding the detailed events of hematopoietic stem cell differentiation.

Alleles↗

PubMed1996

Wilson disease and idiopathic copper toxicosis.

The pathogenic agent of both Wilson disease (WD) and non-Indian childhood cirrhosis (which we term idiopathic copper toxicosis, or ICT) is copper accumulating to excess in the liver. Inheritance of a pair of alleles of an autosomal recessive gene on chromosome 13 is necessary and sufficient to cause such copper accumulation in WD; reducing the dietary intake of copper cannot prevent the development of WD. In contrast, the lethal accumulations of copper in children with ICT have been attributed primarily to an increased dietary intake of copper. However, 64 124 child-year exposures of children under the age of 6 y to drinking water containing a copper concentration of approximately 125.9 micromol/L (8 mg/L) produced no deaths from any form of liver disease. Moreover, the ICT of seven infants was attributed primarily to drinking water containing < 110.2 micromol Cu/L (7 mg/L) despite evidence of the presence of a genetic defect in three of the patients, one of whom was exclusively breast-fed. These data suggest that ICT cannot be caused solely by increased dietary intake of copper and occurs only in children with an identified genetic defect.

Alleles↗