High resolution studies on the pattern of induced exchanges in the human karyotype

The pattern of breakage and exchange induced by X-irradiation of human lymphocytes at G₁ has been analysed in PHA transformed cultures at X₁ metaphase in cells treated with trypsin. All the events observed occurred in interband segments. Moreover, as far as the autosomes were concerned, these events appear to be at random in relation to trypsin interband length but give some indication of non-randomness when total chromosome length is considered. The X and Y chromosomes, on the other hand, show far fewer breaks than would be expected whichever criterion is adopted, and in particular appear to be isolated from the autosomes with respect to the occurrence of exchange events. — The analysis of specific break points in relation to trypsin banding sequences, makes it clear that conclusions regarding chromosome rearrangements based solely on conventional preparations may be misleading.     

Two cases of trisomy 21 and one XXY case with atypical clinical features

Summary Three patients with mental retardation and multiple congenital abnormalities are described.Although their clinical appearance was not suggestive of Down's syndrome, chromosome studies showed a non-disjunctional trisomy 21 in two of the patients. The third case had an unsuspected XXY karyotype.     

Conformity in mate choice,the overlooked social component of animal and human culture

Although conformity as a major driver for human cultural evolution is a well-accepted and intensely studied phenomenon, its importance for non-human animal culture has been largely overlooked until recently. This limited for decades the possibility of studying the roots of human culture. Here, we provide a historical review of the study of conformity in both humans and non-human animals. We identify gaps in knowledge and propose an evolutionary route towards the sophisticated cultural processes that characterize humanity. A landmark in the study of conformity is Solomon Asch's famous experiment on humans in 1955. By contrast, interest in conformity among evolutionary biologists has only become salient since the turn of the new millennium. A striking result of our review is that, although studies of conformity have examined many biological contexts, only one looked at mate choice. This is surprising because mate choice is probably the only context in which conformity has self-reinforcing advantages across generations. Within a metapopulation, i.e. a group of subpopulations connected by dispersing individuals, dispersers able to conform to the local preference for a given type of mate have a strong and multigenerational fitness advantage. This is because once females within one subpopulation locally show a bias for one type of males, immigrant females who do not conform to the local trend have sons, grandsons, etc. of the non-preferred phenotype, which negatively and cumulatively affects fitness over generations in a process reminiscent of the Fisher runaway process. This led us to suggest a sex-driven origin of conformity, indicating a possible evolutionary route towards animal and human culture that is rooted in the basic, and thus ancient, social constraints acting on mating preferences within a metapopulation. In a generic model, we show that dispersal among subpopulations within a metapopulation can effectively maintain independent Fisher runaway processes within subpopulations, while favouring the evolution of social learning and conformity at the metapopulation scale; both being essential for the evolution of long-lasting local traditions. The proposed evolutionary route to social learning and conformity casts surprising light on one of the major processes that much later participated in making us human. We further highlight several research avenues to define the spectrum of conformity better, and to account for its complexity. Future studies of conformity should incorporate experimental manipulation of group majority. We also encourage the study of potential links between conformity and mate copying, animal aggregations, and collective actions. Moreover, validation of the sex-driven origin of conformity will rest on the capacity of human and evolutionary sciences to investigate jointly the origin of social learning and conformity. This constitutes a stimulating common agenda and militates for a rapprochement between these two currently largely independent research areas.     

The differential distribution of X-ray induced chromosome lesions in trypsin-banded preparations from human subjects.

The distribution of X-ray induced aberrations between trypsin-banded regions within human chromosomes has been studied in over a thousand cells from normal and abnormal individuals. An analysis of this data has been performed for each type of aberration separately, taking into account the relative amount of material at risk in reach region. A number of significant deviations from expectation were detected but many of these could be explained in terms of the failure of detection of some aberrations.     

The use of proteolytic enzymes for the mapping of structural rearrangements in the chromosomes of man

Chromosome preparations treated for short periods with the proteolytic enzyme trypsin show well defined banding patterns, comparable to those obtained by more elaborate techniques.—With such patterns it is possible to map in detail the position of chromosome rearrangements.—A rare balanced A1–E18 translocation in a phenotypically normal female and the unbalanced product in her abnormal child has been used to demonstrate this mapping method.     

A further case of a 22;22 Robertsonian translocation associated with recurrent abortions

Summary A case of 22;22 Robertsonian translocation, identified in the husband of a woman who had five early abortions, is reported.     

Rearrangements involving four chromosomes in a child with congenital abnormalities

This report describes a complex structural rearrangement between chromosomes X and 1 and a 7;13 translocation (together involving six break points) in a child with multiple congenital defects. Both parents showed a normal chromosome complement, suggesting that the changes may have originated either in a gametic nucleus or at a very early stage of zygotic development.     

Interstitial deletion of chromosome 7 detected in three unrelated patients

Summary Chromosome studies were carried out on three patients for the following reasons: (1) growth retardation and mental subnormality in a boy; (2) marked developmental delay in a female infant; (3) routine check on a man whose wife had a stillborn with congenital anomalies.An interstitial deletion at 7q11::7q21 was observed in all three cases.