Ultrastructure du fuseau neuro-musculaire chez l'homme

Summary The ultrastructure of the muscle spindles has been studied in human lumbrical muscles. The findings have been compared with the morphology of muscle spindles of rat and sheep examined with light and electron microscopy. The study is based on cross and longitudinal sections of the entire muscle spindle obtained by dissection. The different components of the spindle are described with special reference to the nuclear bag and nuclear chain fibres. These nuclei have been examined in human adult and newborn material and compared to the animal ones. ADN measurements revealed that although there are morphological differences between the two kinds of nuclei in human newborn spindles, the amount of ADN is the same as well in the nuclear bag as in the nuclear chain nuclei. Special attention is also given to the sensory and motor endings in the muscle spindles and to the presence of Pacinian corpuscules in these receptors. Finally two kinds of leptomeric organelles are described in human material.

     

Familial partial trisomy 5p resulting from segregation of an insertional translocation

A case of duplication of segment p13-p15 of the short arm of chromosome 5 as the result of an insertional translocation in a mentally retarded girl with congenital anomalies is reported. Some of the apparently balanced carriers of the inverted insertion showed minor congenital anomalies.     

Trisomy 17p due to a t(8; 17) (p23; p11.2)pat translocation. Case report and review of the literature

We describe a female newborn girl with partial trisomy 17p, which was not detected at the initial cytogenetic investigation, but which later proved to be an unbalanced product of a paternal translocation t(8; 17)(p23;pl 1.2). Comparison with the three previously reported patients suggests a clinically distinct "trisomy 17p syndrome", i.e. pre- and postnatal growth retardation, microcephaly, antimongoloid slanting of palpebral fissures, hypertelorism, long philtrum with thin upper lip, micrognathia and high-arched palate. Two of the four patients had a heart defect, and psychomotor developmental delay was evident in all four cases. In the present patient, the chromosomal anomaly was only detected after the finding of the autosomal reciprocal translocation in the father. The importance of cytogenetic investigations in parents of a MCA/MR child with apparently normal chromosomes is emphasized.     

Absence of aluminium in neurofibrillary tangles in Alzheimer''s disease

Using the new technique of nuclear microscopy, aluminium is not detected in pyramidal neurons in brain tissue from Alzheimer's disease (AD) patients. The analytical technique of nuclear microscopy can simultaneously image and analyse features in unstained and untreated tissue sections. In tissue which had been previously subjected to conventional procedures such as fixation and osmication, aluminium was observed in both neurons and surrounding tissue. This result shows that the analysis of tissue prepared using conventional chemical techniques may produce contamination or elemental redistribution, and supports our previous investigations which implied that aluminium is not involved in the aetiology of AD. In addition, significant increases in iron, phosphorus and sulphur concentrations were noted between neurons from Alzheimer tissue and neurons from age-matched controls, and between the supporting Alzheimer tissue and supporting control tissue, implying an overall increase in these elements. No significant increase in calcium was observed between neurons from Alzheimer tissue and neurons from age-matched controls.     

Chromosome 1q terminal deletion resulting fromde novo translocation with an acrocentric chromosome

Summary Distal deletion of chromosome 1q has been reported in nearly 30 patients, all being associated with a deletion ranging from the 1q42 or q43 band to 1qter region. Here, we describe a girl with 1q terminal deletion resulting from an unbalancedde novo translocation t(1;D or G)(q44; p11), as revealed by the presence of a satellited feature and an NOR-stained region at the tip of 1q. We suggest that most of the phenotypic abnormalities seen in patients with 1q distal deletion are attributable to the monosomy for band 1q44.     

Whole-arm reciprocal translocation (WART) between Robertsonian chromosomes: finding of a Robertsonian heterozygous mouse with karyotype derived through WARTs

The karyotype of a mouse trapped in a hybrid zone between a Robertsonian (Rb) population (2n=22) and a population with the standard karyotype (2n=40-all-telocentrics) shows two Rb chromosomes with new arm compositions. We suggest that whole-arm reciprocal translocations between Rb chromosomes gave rise to the new chromosome constitution and that such events can greatly help in understanding house mouse karyotype diversification and chromosomal speciation.     

Genetic aspects of animal reasoning

This paper reviews the investigations of Prof. L. V. Krushinsky and his colleagues into the genetics of complex behaviors in mammals. The ability of animals to extrapolate the direction of a food stimulus movement was investigated in wild and domesticated foxes (including different fur-color mutants), wild brown rats, and laboratory rats and mice. Wild animals (raised in the laboratory) were shown to be superior to their respective domesticated forms on performance of the extrapolation task, especially in their scores for the first presentation, in which no previous experience could be used. Laboratory rats and mice demonstrated a low level of extrapolation performance. This means that only a few laboratory animals were capable of solving the task, i.e., the percentage of correct solutions was equivalent to chance. The brain weight selection program resulted in two mice strains with a 20% (90-mg) difference in brain weight. Ability to solve the extrapolation task was present in low-brain weight mice in generations 7–11 but declined with further selection. Investigation of extrapolation ability in mice with different chromosomal anomalies demonstrated that animals with Robertsonian translocations Rb(8,17) 1lem and Rb(8,17) 6Sic were capable of solving this task in a statistically significant majority of cases, while mice with fusion of other chromosomes, as well as CBA normal karyotype mice, performed no better than expected by chance. Mice with two types of partial trisomies and animals homo- and heterozygous for translocations were also tested. Although mice with T6 trisomy performed no better than expected by chance, animals with trisomy for a chromosome 17 fragment solved the task successfully. Thus, a genetic component underlying the ability to solve the extrapolation task was demonstrated in three animal species. The extrapolation task in animals is considered to reveal a general capacity for elementary reasoning. The genetic basis of this capacity is very complex.     

Molecular characterization of a complex translocation in a newborn infant

A newborn infant was referred because of low-set ears, mild downward slant of the palpebral fissues, micrognathia with higharched palate, a flat midface, small mouth, and thin upper lip with cupid bow configuration. To some extent her cry resembled that associated with cri du chat syndrome. Cytogenetic findings with G- and Q-banding alone failed to characterize precisely the complex translocations. By the chromosome in situ suppression (CISS) hybridization technique using whole chromosome specific probes, a complex 4 breakpoint rearrangement involving both arms of a single chromosome 1 with the long arms of chromosome 5 and 11 was disclosed, i.e., 46,XX, der(1),t(1;5) t(1;11) (5qter→5q31::1p31.3→1q44::11q23→11qter;5pter→5q31::1p31.3→1pter;11pter→11q23::1q44→1qter). Gene deregulation and position effect may explain the multiple anomalies in individuals with apparently balanced translocations may shed some light towards unveiling the clinical consequences associated with aberrations which are presumably balanced. © 1993 Wiley-Liss, Inc.     

Ultrastructural studies of spermatozoa from infertile males with Robertsonian translocations and 18, X, Y aneuploidies

BACKGROUND: In order to clarify the relationship between chromosomal rearrangements, sperm morphology and interchromosomal effects (ICE), we studied the spermatogenetic defects in seven infertile Robertsonian translocation carriers. METHODS: Lymphocyte karyotypes were evaluated using Giemsa-Trypsin-Giemsa banding and fluorescence in-situ hybridization (FISH). Semen analysis was performed by light and transmission electron microscopy. FISH of sperm nuclei was carried out to detect possible ICE. RESULTS: Lymphocyte karyotype analysis revealed five t(13;14), one t(13;21) and one t(14;22) carriers. Sperm ultrastructural examination highlighted a higher percentage of immaturity, apoptosis and necrosis than in controls. Aneuploidies of gonosomes were detected in sperm from five out of six carriers of Robertsonian translocation, whereas aneuploidy of chromosome 18 was evident in three out of six carriers. The frequencies of diploidy were altered in all cases. CONCLUSIONS: Since these infertile patients showed severe spermatogenetic impairment from the morphological and meiotic points of view, we recommend detailed sperm ultrastructural and chromosomal analysis before undertaking ICSI cycles in Robertsonian translocation carriers.     

Characterization of a galactose-1-phosphate uridylyltransferase gene from the marine red alga Gracilaria gracilis

The metabolism of D-galactose is a major feature of red-algal physiology. We have cloned and sequenced a gene from the red alga Gracilaria gracilis that encodes a key enzyme of D-galactose metabolism, galactose-1-phosphate uridylyltransferase (GALT). This gene, designated GgGALT1, is apparently devoid of introns. A potential TATA box, four potential CAAT boxes, and a repeated sequence occur in the 5′-flanking region. The predicted 369-aa peptide shares significant sequence similarity with GALTs from other organisms (human, 47%; Saccharomyces cerevisiae, 49%; Solanum tuberosum, 49%). Southern-hybridization analysis reveals two related, but apparently not identical, GALT genes in the nuclear genome of G. gracilis. Sequence analysis indicates that the GgGALT1 enzyme lacks a rubredoxin “knuckle” motif, which in bacterial and fungal GALTs is involved in binding zinc. An open reading frame encoding a potential peptidyl tRNA hydrolase occurs 179 bp downstream from the GgGALT1 gene. Received: 6 April / 2 June 1998