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PubMed1987

Genotoxicity of metacid established through the somatic and germ line mosaic assays and the sex-linked recessive lethal test in Drosophila.

The mutagenic potential of metacid (methyl parathion), an anticholinesterase organophosphate pesticide, has been studied in the Drosophila eye, wing and female germ line assays and the sex-linked recessive lethal tests. Larvae 24 h, 48 h and 72 h old, heterozygous for various recessive genetic markers on the first and third chromosomes, were exposed to the LD50 and half of this dose for different periods of time. The eyes and wings were checked for the presence of mosaic spots and eggs laid by the females for germ line mosaicism. The M-5 technique was used to detect the induction of sex-linked recessive lethals. It is concluded that metacid is mutagenic in somatic and germ line cells of Drosophila and induces sex-linked recessive lethals in immature male germ cells.

Animals↗
PubMed1990

Hereditary palmoplantar keratosis of the Gamborg Nielsen type. Clinical and ultrastructural characteristics of a new type of autosomal recessive palmoplantar keratosis.

A new kind of diffuse palmoplantar keratoderma with autosomal recessive inheritance and without associated symptoms was described in Norrbotten, Sweden by Gamborg Nielsen in 1985. Clinically, it ranges between the less severe dominant Unna-Thost type and the more severe recessive Meleda type, as it is milder than the latter. Skin biopsies of five patients from three different families with this new palmoplantar keratoderma, as well as five obligatory heterozygotes from one family, were investigated ultrastructurally in order to characterize this new entity and to differentiate it from the Meleda type. Several features are common to both autosomal recessive palmoplantar keratoses. They show a broadened granular layer, a transit region consisting of cells with a marginal envelope, and considerable hyperkeratosis. Morphologically, this transformation delay is less pronounced in the Gamborg Nielsen type than in the classical Meleda type. As is typical for ridged skin, both types of palmoplantar keratoses possess composite keratohyaline granules. In contrast to the normal appearance of keratohyaline granules in the Meleda type, the Gamborg Nielsen type also shows qualitative deviations of keratohyaline granules with different degrees of spongiosity and electron density and sometimes with a granular border. It seems that abnormal keratohyaline proteins are synthesized that behave differently. The sudden transformation of a granular into a horny cell is physiologically regulated by different enzymes. A delay in this process may be caused by a mutation that reduces or alters the enzymes concerned. We assume the palmoplantar keratoderma of the Gamborg Nielsen type to be a variant of the heterogeneous group of the Meleda type of palmoplantar keratoderma with autosomal recessive inheritance.

Female↗
PubMed1997

Autosomal recessive distal muscular dystrophy.

The "distal myopathies" include autosomal dominant, autosomal recessive, and sporadic disorders. Two of the recessive disorders are considered to be definitive entities: Miyoshi's myopathy, which has an early adult onset and first involves the calf muscles, and distal myopathy with rimmed vacuoles. We here describe the cases of two sisters and compare them with previously reported cases. The disorder in our patients is characterised by: a) autosomal recessive inheritance; b) onset in early adult life; c) initial involvement of the tibialis anterior and peroneal muscles; d) subsequent involvement of the calf muscles spreading to the proximal muscles of the legs and, later, the arms; e) a moderately disabling evolution over a period of 10-12 years; f) marked and stably high serum levels of CK and other enzymes; g) EMG evidence of myopathic damage, with fibrillation at rest; and h) a histological picture of dystrophic myopathy, with atrophy of mainly type 2 fibres. We think that this syndrome is different from the two forms of autosomal recessive distal myopathy mentioned above.

Adolescent↗
PubMed2005

Targeting xa13, a recessive gene for bacterial blight resistance in rice.

Bacterial blight, caused by Xanthomonas oryzae pv. oryzae (Xoo), is one of the most serious diseases of rice worldwide. Thirty bacterial blight resistance (R) genes (21 dominant genes and 9 recessive genes) in rice have been identified. They are the main sources for the genetic improvement of rice for resistance to Xoo. However, little is known about the recessive R genes. To clone and characterize the recessive R genes, we fine-mapped xa13, a fully recessive gene for Xoo resistance, to a DNA fragment of 14.8 kb using the map-based cloning strategy and a series of sequence-based molecular markers. Sequence analysis of this fragment indicated that this region contains only two apparently intact candidate genes (an extensin-like gene and a homologue of nodulin MtN3) and the 5' end of a predicted hypothetical gene. These results will greatly facilitate the isolation and characterization of xa13. Four PCR-based markers, E6a, SR6, ST9 and SR11 that were tightly linked to the xa13 locus, were also developed. These markers will be useful tools for the marker-assisted selection of xa13 in breeding programs.

Chromosomes, Plant↗
PubMed2001

The complex clinical and genetic classification of inherited ataxias. II. Autosomal recessive ataxias.

Autosomal recessive ataxias are a heterogeneous group of rare neurodegenerative diseases characterized by early onset cerebellar ataxia associated with various neurologic, ophthalmologic and systemic signs. In comparison with autosomal dominant ataxias, the group of recessive ataxias is less extensively characterized. In fact, only a few conditions have been genetically characterized. The pathogenesis of these forms is associated with a "loss of function" of specific cellular proteins involved in metabolic homeostasis, cell cycle, and DNA repair/protection processing. The two most common autosomal recessive ataxias, in European countries, are Friedreich's ataxia and ataxia telangiectasia. Other forms are much less frequent, and include ataxia with vitamin E deficiency, abetalipoproteinemia. Refsum's disease, spastic ataxia, infantile onset spinocerebellar ataxia, and ataxia with oculomotor apraxia. These pathological conditions, although extremely rare, have nevertheless to be carefully considered in differential diagnosis, not only for correct nosographical classification, but particularly, for specific prognostic and therapeutic implications. Some of these diseases exhibit a peculiar regional distribution. An updated review of the clinical, genetic, and pathogenic aspects of recessive ataxias is presented. Specific management problems with respect to diagnosis and genetic counseling are discussed.

Ataxia Telangiectasia↗
PubMed1983

Clonal analysis of the tissue specificity of recessive female-sterile mutations of Drosophila melanogaster using a dominant female-sterile mutation Fs(1)K1237.

Using the newly isolated, germ line-dependent dominant female-sterile mutation Fs(1)K1237, we have characterized the germ line or somatic line dependence of 25 X-linked recessive female-sterile mutations. Since Fs(1)K1237/+ females fail to lay eggs, only germ line cells which lose Fs(1)K1237 as a result of X-ray-induced mitotic recombination are capable of producing eggs. Such recombination events will render genes on the homologous chromosome homozygous. If this chromosome carries a recessive female-sterile mutation, the fertility will be restored only if the altered function is not required in the germ line. Using this test, we have classified 25 recessive female-sterile mutations: 12 affect germ line function, 12 affect somatic line function, and one gave an ambiguous result for which an explanation is proposed. For a few of the somatic line-dependent mutants, we found that some eggs derived from germ line clones showed the same phenotype as eggs laid by females homozygous for the recessive female-sterile mutation. These results are discussed in terms of a coincident production of clones in the follicle cells.

Animals↗
PubMed1986

The frequency of dominant cataract and recessive specific-locus mutations in mice derived from 80 or 160 mg ethylnitrosourea per kg body weight treated spermatogonia.

A systematic comparison of the frequency of dominant cataract and recessive specific-locus mutations in mice has been extended to include results for 80 and 160 mg ethylnitrosourea per kg body weight spermatogonial treatment. The frequency of confirmed dominant cataract mutations in the historical control, 80 and 160 mg/kg ethylnitrosourea treatment groups was 1/22594, 8/5090 and 14/6435, respectively. The frequency of recessive specific-locus mutations in the same dose groups was, respectively, 19/227805, 20/13274 and 35/8658. These present results confirm previous results, which indicate that ethylnitrosourea is effective in inducing both recessive specific-locus and dominant cataract mutations although the per locus mutation rate to recessive alleles was observed to be approximately 6 times greater than the per locus mutation rate to dominant alleles. The exclusion of certain classes of lens opacity variant phenotypes, previously demonstrated not to be due to a dominant mutation, from the group of suspected dominant cataract mutations subjected to a genetic confirmation test has greatly improved the efficiency of the test. A total of 23 dominant cataract mutations were confirmed from a group of 67 phenotypic variants. Of the 23 confirmed dominant cataract mutations, 8 were shown to have reduced transmission to the following generation of offspring expressing the mutant phenotype. These results are also consistent with previous results for ethylnitrosourea or radiation treatment in which it was shown that approximately one-third of the recovered mutations have reduced penetrance. One group of dominant cataract mutations, with phenotypic effects on the polar, sub-capsular or corneal regions, is overly represented in the group of recovered mutations with a reduced transmission of offspring expressing the mutant phenotype. Two hypotheses are suggested for this observation, both dependent on the fact that the regions affected indicate that the mutations are expressed later in the development of the eye. Either all carrier individuals have not expressed the phenotype at the time of examination and classification, or later acting mutations are more subject to environmental interactions resulting in more variable expression. Finally, it is argued that a dominant cataract mutation test represents a most practicable protocol to screen for induced dominant mutations in germ cells of the mouse. The imposition of the criterion that suspected variants be subjected to a genetic confirmation test has at least two advantages beside the fact that results represent unambiguous mutational events.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1993

Studies on mutagen sensitive strains of Drosophila melanogaster. XI. Survival (dominant lethality) after X-irradiation and relation to recessive lethals and translocations.

Muller-5 males of Drosophila melanogaster were irradiated in N2 or O2 and mated to excision repair deficient, post-replication repair deficient (mei-9a, mei-41D5, mus101D1, mus201D1, mus302D1, mus306D1 and mus308D2) or repair proficient females. The surviving fraction (dominant lethality) was estimated in the F1 and used to reassess existing recessive lethal and translocation data. The surviving fraction was found to decrease if repair deficient females were used (maternal effect). The dose-effect curves are often biphasic with a steeper slope at low doses than at high (> or = 5 Gy) doses of X-rays. The high dose part of the curve is sensitive to oxygenation during irradiation and is affected significantly by the mutants with low fertility (mei-9, mus101 and mus302). The low dose component is not sensitive to oxygenation during irradiation and seems influenced by all seven repair deficient mutants. The sensitivity of the high dose part to oxygenation suggests that this part is related mainly to DNA break damage, while in the low dose part base damage seems more important. Existing recessive lethal and translocation data were plotted against the surviving fraction for a reassessment. In excision repair deficient mutants translocation induction is lower compared to repair proficient flies at the same level of survival (i.e., dominant lethality). Likewise in post-replication repair deficient mutants induction of recessive lethals is decreased. However the frequency of respectively induced recessive lethals and translocations obtained at the same level of X-rays was the same in repair deficient and proficient backgrounds. It is concluded that genetic damage recovered in a repair deficient background is likely to be qualitatively different even if the frequency of the damage induced by a given dose is not altered.

Animals↗
PubMed1994

X-ray-induced specific-locus mutations in the ad-3 region of two-component heterokaryons of Neurospora crassa. XII. Analysis of multiple-locus ad-3 mutations reveals a nonrandom distribution of the separate sites of recessive lethal damage throughout the genome.

Previous studies on X-ray-induced adenine-3 mutations induced in heterokaryon 12 of Neurospora crassa showed that they consisted of gene/point mutations, multilocus deletion mutations, and 3 different genotypic classes of multiple-locus mutations (designated [-3]IR + RLCL, ad-3R + RLCL, and ad-3R + RL). In the present paper, multiple-locus mutations consisting of gene/point mutations at the ad-3A or the ad-3B locus with sites of recessive lethal damage closely linked to the ad-3 region (designated ad-3R + RLCL) or with sites of recessive lethal damage elsewhere in the genome (designated ad-3R + RL) were analyzed to determine whether they resulted from mutations at the same sites or different sites throughout the genome. It was assumed that if the recessive lethal mutations in individual multiple-locus mutations showed complementation on adenine-supplemented medium, they resulted from mutations at different sites. Multiple-locus mutations from both major genotypic classes were combined, as forced heterokaryons, in all possible pairwise combinations and then were plated out on adenine-supplemented medium. These studies indicated that 89.3% (50/56) of the recessive lethal mutations in these 2 classes of multiple-locus mutations complement one another. Thus, they are presumed to have resulted predominantly from genetic damage at different sites throughout the genome. Within the group of 20 multiple-locus mutations that did not complement in various pairwise combinations, 90% (18/20) appear to map in a region, distal to the ad-3 region, defined by a series of overlapping multilocus deletion mutations in 6 mutations of genotype ad-3R + RLCL. The other 10% (2/20) are located elsewhere on Linkage Group I or elsewhere in the genome. The present data base on multiple-locus mutations is unique; such events either can not be detected, or can only be detected with difficulty, in other eukaryotic specific-locus assay systems such as mammalian cells in culture, Drosophila or mice. Our data on X-ray-induced ad-3 specific-locus mutations from the present and previous studies demonstrate the presence of additional sites of genetic damage, both closely linked with the ad-3 region or elsewhere in the genome, in ad-3 specific-locus mutations. Because the frequencies of each class of multiple-locus mutations is dose-dependent, they must be taken into account in genetic risk assessment exercises. Failure to acknowledge the presence of such additional sites of genetic damage in the utilization of specific-locus data could result in underestimation of the risk of human exposure to environmental mutagens.

Adenine↗
PubMed1991

Recessive hereditary deafness, assortative mating, and persistence of a sign language.

We model the cultural transmission of sign language when there is one-locus genetic variation for deafness and hearing. Our premises are that the deaf are more motivated to learn sign language than the hearing, and that a vertically transmitted sign language, unlike recessive hereditary deafness, cannot "jump a generation." Conditions are obtained for persistence (i.e. protection from loss) of signers. These conditions are more easily satisfied the greater the fraction of the hearing who also learn sign language and as the frequency of the recessive gene for deafness increases. Persistence is also facilitated by assortative mating for deafness, but not by assortment for signing. With vertical transmission only, it is necessary that one signer parent be able to transmit sign language with greater than one-half the efficiency of two. Under the assumption that the hearing do not learn sign language, the following additional results are obtained. Persistence is more likely with dominant as opposed to recessive inheritance. When recessive hereditary and acquired deafness co-occur, increasing the frequency of the latter has opposite effects depending on the degree of assortment. Opportunities for the deaf to learn sign language outside the family seem not to affect the conditions for persistence.

Deafness↗
PubMed1988

Genotoxicity of Rogor studied in the sex-linked recessive lethal test and wing, eye and female germ-line mosaic assays in Drosophila melanogaster.

The genotoxic potential of Rogor (dimethoate), an anticholinesterase organophosphate insecticide, has been studied in the sex-linked recessive lethal test and the wing, eye and female germ-line mosaic assays in Drosophila melanogaster. Larvae of different instars carrying suitable recessive genetic markers on their first and third chromosomes were exposed to the LD50 or half of this dose for the entire larval life. The Basc technique was followed for the detection of the induction of sex-linked recessive lethals. The wings and eyes of the adult flies and the eggs laid by the heterozygous females were checked for the induction of mosaicism. It is concluded that Rogor induces sex-linked recessive lethals in immature male germ cells and is recombinogenic and/or mutagenic in both the somatic and the germ-line cells of Drosophila.

Animals↗
PubMed1989

Observations on chromosome loss detection by multiple recessive marker expression in strain D61.M of Saccharomyces cerevisiae.

Since chromosomes of fungi are difficult to observe directly, strains have been developed in which chromosome loss can be detected by the use of genetic markers. In the diploid D61.M strain of Saccharomyces cerevisiae, the loss of a copy of chromosome VII that carries 3 dominant wild-type alleles is measured by expression of 3 recessive mutant alleles carried on the other remaining copy of chromosome VII. We have tested the hypothesis that expression of the 3 recessive alleles might be due to 3 simultaneous independent genetic events other than chromosome loss, such as mutation or recombination. We have measured, when possible, the frequencies of expression for each of these recessive alleles, independently and in combination one with another, under both selective and non-selective conditions. Our results show that simultaneous expression of these 3 recessive alleles is attributable to chromosome loss (greater than 98%). Similarly, at least 99% of the nocodazole-induced events are attributable to chromosome loss. In contrast, most if not all of the apparent chromosome loss induced by ethyl methanesulfonate is due to multiple events of mutation or recombination.

Adenine↗
PubMed1995

A gene for autosomal recessive nemaline myopathy assigned to chromosome 2q by linkage analysis.

Clinical genetic evidence suggests the existence of an autosomal recessive form of congenital nemaline myopathy in addition to the autosomal dominant one(s). One mutation in an Australian kindred has been identified as causing an autosomal dominant form of the disease. This mutation in the alpha-tropomyosin gene TPM3 has previously been excluded as causing autosomal recessive nemaline myopathy. We searched systematically for genetic linkage to autosomal recessive nemaline myopathy (NEM2) by studying microsatellite marker alleles in seven multiplex families from Finland, Denmark, Wales, England and The Netherlands. Significant evidence of linkage was found to markers of chromosome 2q, the highest multipoint lod score value being 5.34 for the marker D2S151. Recombinant genotypes in affected individuals demarcate the the region in which the NEM2 gene is likely to reside as a 13 cM region between the markers D2S150 and D2S142. These results confirm the existence of at least one distinctive form of autosomal recessive nemaline myopathy and provide a basis for the identification of its gene.

Australia↗
PubMed2000

A new locus for autosomal recessive limb-girdle muscular dystrophy in a large consanguineous Tunisian family maps to chromosome 19q13.3.

Autosomal recessive limb-girdle muscular dystrophies represent a genetically heterogeneous group of diseases characterized by a progressive involvement of skeletal muscles. They show a wide spectrum of clinical courses, varying from very mild to severe. Eight loci responsible for autosomal recessive limb-girdle muscular dystrophies have been mapped and six defective genes identified. In this study, we report the clinical data, muscle biopsy findings and results of genetic linkage analysis in a large consanguineous Tunisian family with 13 individuals suffering from autosomal recessive limb-girdle muscular dystrophy. Clinical features include variable age of onset, proximal limb muscle weakness and wasting predominantly affecting the pelvic girdle, and variable course between siblings. CK rate was usually high in younger patients. Muscle biopsy showed dystrophic changes with normal expression of dystrophin and various proteins of the dystrophin-associated protein complex (sarcoglycan sub-units, dystroglycan, and sarcospan). Genetic linkage analysis excluded the known limb-girdle muscular dystrophies loci as well as ten additional candidate genes. A maximum LOD score of 4.36 at θ=0.00 was obtained with marker D19S606, mapping this new form of autosomal recessive limb-girdle muscular dystrophy to chromosome 19q13.3.

Adolescent↗
PubMed2003

Rare forms of autosomal recessive neurodegenerative ataxia.

There has been a recent explosion in knowledge regarding the genetic basis of several autosomal recessive ataxias. This article summarizes current information regarding rare forms of recessive ataxias. Friedreich's ataxia and ataxia telangiectasia are dealt with in other articles in this issue. The rarer recessive ataxias can be clinically classified as sensory and spinocerbellar ataxias, cerebellar ataxia with sensory-motor polyneuropathy, and purely cerebellar ataxias. Examples of the first category include ataxia with isolated vitamin E deficiency, abetalipoproteinemia, Refsum's disease, infantile-onset spinocerebellar ataxia, and ataxia with blindness and deafness. Examples of ataxia with sensory-motor polyneuropathy include ataxia with oculomotor apraxia 1 and 2 and spinocerebellar ataxia with neuropathy 1. Examples of purely cerebellar ataxia include autosomal recessive spastic ataxia of Charlevoix-Saguenay and ataxia with hypogonadotropic hypogonadism. This review summarizes the clinical and genetic features of these entities and concludes that the pathogenic basis of such ataxias at this time appear to involve two broad types of processes: free-radical injury and defects of DNA single- or double-strand break repair.

Cerebellar Ataxia↗
PubMed1996

Recession of the soft tissue margin at oral implants. A 2-year longitudinal prospective study.

The aim of this study was to longitudinally evaluate alterations in the position of the periimplant soft tissue margin, occurring during a 2-year period after insertion of fixed prostheses. 41 patients, subjected to treatment with partial or full-arch implant supported fixed prostheses based on a total of 163 standard Brånemark oral implants, were included in the study. A baseline examination was performed at time of insertion of the prosthetic construction and involved assessments of plaque, mucositis, probing depth, bleeding on probing marginal soft tissue level, width of masticatory mucosa and marginal soft tissue mobility. All patients were re-examined after 6 months, and after 1 and 2 years, respectively. A regression analysis was performed to evaluate if alterations, occurring in the position of the periimplant soft tissue margin during the 2 years, could be predicted by various variables recorded at time of the installation of the fixed prosthesis. The descriptive analysis showed a slight decrease in mean probing depth (0.2 mm) and width of masticatory mucosa (0.3 mm) during the follow-up period. Apical displacement of the soft tissue margin mainly took place during the first 6 months of observation. Lingual sites in the mandible showed the most pronounced soft tissue recession, decrease of probing depth, and decrease of width of masticatory mucosa. The statistical analysis revealed that lack of masticatory mucosa and mobility of the periimplant soft tissue at time of bridge installation were poor predictors of soft tissue recession occurring during the 2 years of follow-up, but indicated in greater amount of recession in women than men, in the mandible than in the maxilla, at lingual than at facial sites and with increased initial probing depth. It was suggested that the recession of the periimplant soft tissue margin mainly may be the result of a remodelling of the soft tissue in order to establish "appropriate biological dimensions" of the periimplant soft tissue barrier, i.e., the required dimension of epithelial-connective tissue attachment in relation to the faciolingual thickness of the supracrestal soft tissue.

Adult↗
PubMed1999

Gingival recession and toothbrushing in an Italian School of Dentistry: a pilot study.

The aim of this pilot study was to evaluate the prevalence of gingival recession at buccal tooth surfaces in a student population of Bologna University Dental School. A total of 55 subjects, attending the 1st and 5th year of the course were examined. The clinical examination involved assessment of plaque, calculus, width of keratinized gingiva, buccal probing depth and buccal gingival recession. Information about toothbrushing behavior was collected in an interview. The multiple regression analysis showed that level of education (p=0.002), toothbrushing technique (p=0.013) and toothbrushing frequency (p=0.016) are significant contributors to gingival recession. Notwithstanding the limits of a preliminary study, a higher prevalence of buccal recession is observed in the final year students, which have also a significantly lower % of buccal surfaces with calculus (p=0.014). In addition, it clearly appears that there is the necessity to investigate other factors connected with toothbrushing (pressure, time, toothpaste quantity) in order to provide an oral hygiene education without undesired effects.

Adult↗
PubMed1999

Mutations in the human homologue of mouse dl cause autosomal recessive and dominant hypohidrotic ectodermal dysplasia.

X-linked hypohidrotic ectodermal dysplasia results in abnormal morphogenesis of teeth, hair and eccrine sweat glands. The gene (ED1) responsible for the disorder has been identified, as well as the analogous X-linked gene (Ta) in the mouse. Autosomal recessive disorders, phenotypically indistinguishable from the X-linked forms, exist in humans and at two separate loci (crinkled, cr, and downless, dl) in mice. Dominant disorders, possibly allelic to the recessive loci, are seen in both species (ED3, Dlslk). A candidate gene has recently been identified at the dl locus that is mutated in both dl and Dlslk mutant alleles. We isolated and characterized its human DL homologue, and identified mutations in three families displaying recessive inheritance and two with dominant inheritance. The disorder does not map to the candidate gene locus in all autosomal recessive families, implying the existence of at least one additional human locus. The putative protein is predicted to have a single transmembrane domain, and shows similarity to two separate domains of the tumour necrosis factor receptor (TNFR) family.

Alleles↗