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Biomedical subjects

C A Redi

Publications and source records attributed to C A Redi.

62 records · Page 4Linked to original sources
PubMedDate not supplied

Human-dominated ecosystems and restoration ecology: Seveso today.

Seveso is a town (40,000 inhabitants) 16 km north of Milan, which from 10 July 1976 became synonymous with the chemically induced ecological catastrophe because of the large number of people affected by dioxin exposure and of the large area involved. The most polluted area (about 43 ha) was artificially reconstructed and transformed into a wood composed mainly of oaks with some scattered green fields and some bushy areas, the Bosco delle Querce urban park. A four-year survey monitoring the present ecological and biological risk parameters of the artificially reconstructed ecosystem shows its full ecological recovery as an urban park. Plant and animal coenoses are well composed and the park has been colonized by annelids, insects, amphibians, reptiles, birds and mammals. All these animals are useful biological reagents for risk-assessment because of their potential long-term exposure to TCDD. When some of the endpoints of the xenoestrogen-like molecules' action were studied (i.e., gametogenesis and the gross morphology of genital organs in rabbits and house mice), no signs of TCDD effects were detected. Mutagenicity tests and the house mouse sperm DNA COMET assay do not reveal the presence of any biological risk. The study of the carabidocoenosis and the housefly cytogenetics corroborates this last indication, thus guaranteeing the successful ecological recovery of the formerly most polluted Seveso area.

Amphibians↗
PubMedDate not supplied

Stage-dependent enzymatic activities in spermatogenesis of mice with the standard karyotype and of chromosomal variants with impaired fertility.

The enzymatic activities of thiamine pyrophosphatase (TPPase), acid phosphatases (ACPases), alkaline phosphatases (APases) and steroid-3 beta-ol dehydrogenase (beta-HSDH) in different germ cells and somatic cells in the testis of three cytogenetically determined states of fertility (i.e. normal, impaired fertility and sterility) were studied histochemically in the mouse. The TPPase, ACPases and APases activities showed a characteristic stage dependent pattern when the activities were related to the typical twelve stages of the seminiferous epithelium in the mouse, according to Oakberg (1956). Comparing the enzymatic patterns of the activities in the normal spermatogenic process versus the impaired and sterile conditions, the following conclusions can be drawn: even in impaired and sterile conditions the enzymatic activity patterns retain their characteristic stage dependence; the pattern of beta-HSDH and ACPases is not altered in the impaired and sterile conditions; TPPase and APases patterns are modified in impaired and sterile mice. It is concluded that the kinetics of the enzyme activities can serve as a useful marker for characterizing pathological spermatogenic processes.

3-Hydroxysteroid Dehydrogenases↗
PubMedDate not supplied

Relative positions of the spermatogenic stages in the mouse testis: morphological evidences for their non-randomized adjacencies.

The topographical distribution pattern of the stages of the murine seminiferous epithelium cycle was investigated. PAS-hematoxylin stained testicular sections from adult mice representative of the apical, equatorial and caudal region of both testes, were used. The relative frequencies (RF) of the stages of the seminiferous epithelium cycle was estimated on the basis of more than 10,000 cross-sectioned seminiferous tubules identified according to the criteria of Leblond and Clermont (1952). It was found that in the testicular sections the stages of adjacent seminiferous tubules are not distributed randomly. The comparison of the RF of the stages (calculated over all the testicular sections) with the RF of the stages that are adjacent to a given seminiferous tubule stage suggests a clustered occurrence of numerically identical stages. These comparisons very often show statistically significant differences. The finding of such associations among adjacent segments of seminiferous tubules (stages) suggest the existence of an ordered distribution of the seminiferous tubules inside the testis possibly controlled by substances with local control capacity of spermatogenesis. On the basis of the findings here presented, it is suggested an interpretation of the phenomenon of modulations of the waves of the seminiferous epithelium.

Animals↗
PubMedDate not supplied

Chromosome variability and germ cell development in the house mouse.

Structural heterozygosities of the karyotype have detrimental effects on the meiotic process, resulting very often in impairment of fertility in the carriers. Both male and female germ cell development are affected by chromosomal variability although spermatogenesis seems particularly prone to be affected, probably because of the intrinsic characteristics of the male germ cell cytodifferentiation process (i.e. the histological architecture of the seminiferous epithelium). However, euploid and aneuploid sperm do not seem to differ in the molecular organization of the genome they carry, thus explaining the almost regular capacity to accomplish the first zygotic developmental stages by the aneuploid sperm (aneuploid both for gametogenic genes and for entire chromosomal arms). A survey of the molecular and morphological data available on germ cell development in conditions of chromosomal rearrangement leads to the conclusion that the current hypotheses accounting for this phenomenon can only partly explain it. A working hypothesis is proposed which considers the three-dimensional changes (produced by structural heterozygosity) in the spatial order of chromosomes within the nucleus as the primary cause potentially able to trigger distorted functioning of the germ cells.

Aneuploidy↗
PubMedDate not supplied

Fluorescence energy transfer shows that various physical and chemical treatments of human sperm induce unpacking of chromatin.

Fluorescence resonance energy transfer (FRET) was used to study the changes which human sperm chromatin went through after various physical and chemical treatments. This technique showed a dilatation of the spatial relationship among chromatin liner arrays, with UV and DNAse among the treatments that gave rise to the highest increase. FRET image analysis showed that the chromatin linear arrays after treatment reach a spatial disarrangement similar to that brought about by sperm decondensation. Comparison of these results with the ability of human treated sperm to form pronuclei after microinjection into hamster eggs, suggests that the highly condensed spatial organization of sperm chromatin arrays may not be a necessary prerequisite for pronucleus formation.

Animals↗