The discovery of the human chromosome number in Lund, 1955–1956

The correct determination of the human diploid chromosome number as 46, by J-H Tjio and A Levan, at the University of Lund, Sweden, occurred 50 years ago, in December 1955; the finding was published in April 1956, ending a period of more than 30 years when the number had been thought to be 48. The background to the discovery and the surrounding factors are reassessed, as are the reasons why previous investigators persistently misidentified the precise number. The necessity for multiple technological advances, the power of previously accepted conclusions in influencing the interpretation of later results, and the importance of other work already undertaken in Lund, are all relevant factors for the occurrence of this discovery, the foundation for modern human cytogenetics, at this particular time and place.     

The chromosome number in humans: a brief history

Following the rediscovery of Mendel's work in 1900, the field of genetics advanced rapidly. Human genetics, however, lagged behind; this was especially noticeable in cytogenetics, which was already a mature discipline in experimental forms in the 1950s. We did not know the correct human chromosome number in 1955, let alone were we able to detect a chromosomal abnormality. In 1956 a discovery was reported that markedly altered human cytogenetics and genetics. The following is an analysis of that discovery.     

Personal reflections on the life and legacy of Alexander Hollaender

Mary Esther Gaulden presents a personal summary of the activities of Alexander Hollaender, from his days at the National Institutes of Health to his becoming Director of the Biology Division of the Oak Ridge National Laboratory in 1947. This appealing story deals with many of her reactions to his personality and organizational style. It reflects the atmosphere of science in those days, and her enthusiasm in this vibrant milieu. Next is a brief account by John Jagger of his first meeting with Dr. Hollaender, arrival in Oak Ridge in April 1956, and wedding to Mary Esther six months later at the house of the Hollaenders in Oak Ridge. The third section is an account by Virginia P. White of how she came to Oak Ridge in 1955 and became Dr. Hollaender's Laboratory Administrator. She gives a personal account of the many facets of his managerial style, as well as of the personality of his wife, Henrietta. She also describes one of Hollaender's many avocations, the collection of fossils on Sunday morning hikes in the Cumberland Mountains, accompanied by lab and visiting personnel, and finally comments on the annual research conferences in Gatlinburg TN, for which Hollaender and the lab became very well known, with some closing vignettes on his leadership style.     

The Goldwyn diary of November and December 1960, at the Albert Schweitzer Hospital, Lambaréné, Gabon

Through unexpected circumstances, I went to Lambaréné, in Gabon, to be Dr. Albert Schweitzer's surgeon for 2 months, November and December of 1960.This diary I can honestly say I never thought would become public. The years have passed; I am now 77. I realize that not many of those who served in a medical capacity at his hospital are still alive and not everyone will share his or her experiences.I want to make clear that I was with Dr. Schweitzer only 2 months. I would not want anyone to think that I played a strategic role at the hospital. I did not, but I helped as best I could.Although I have traveled throughout the world and have been a surgeon in many out-of-the-way places, I have not returned to Lambaréné. The reason, I confess, is that I wanted it to remain in my mind as it was. For Dr. Schweitzer and those who served there, his hospital was a way of life. It was a world of its own and, though small, it came into being because of the arching ideals and unflagging dedication of a remarkable man. His example should inspire us to enlarge our personal horizons, not just to recognize the less fortunate but to act without delay on their behalf. For each of us, there is an Ogowe waiting to be crossed.     

Investigations of Ion Uptake by Tissue Slices II. The effect of 2,4-diuitrophenol on the uptake of calcium hy potato slices

DNP (2,4-dinitrophenol) has been found by a number of investigators to inhibit both anion and cation uptake in a variety of plant tissues (Arisz 1953, Hopkins 1956, Middleton 1955, Ordin and Jacobson 1955, Robertson et al. 1951, Russell and Ayland 1955). Following some preliminary investigations, Chasson and Levitt (1956) reported in a brief note that calcium uptake by potato slices was stimulated by the addition of DNP. Presented below are the results of a more thorough study of these initial observations.     

Genetic analysis of the maximum drinks phenotype

Using data provided by the Collaborative Study on the Genetics of Alcoholism we studied the genetics of a quantitative trait: the maximum number of drinks consumed in a 24-hour period. A two-stage method was used. First, linkage analysis was performed, followed by association analysis in regions where linkage was detected. Additionally, the extent of linkage disequilibrium among single-nucleotide polymorphisms (SNP) associated with the phenotype was assessed. Linkage to chromosomes 2 and 7 was detected, and follow-up association analysis found multiple trait-associated SNPs in the chromosome 7 linkage region. Chromosome 4, which has been implicated in previous studies of the maximum drinks phenotype, did not pass our threshold for linkage evidence in stage 1, but secondary analyses of this chromosome indicated modest evidence for both linkage and association. The evidence suggests that chromosome 7 may harbor an additional locus influencing the maximum drinks consumption phenotype.     

Sinking losses of phytoplankton in closed limnetic systems

Specific algal recoveries from sediment traps of two differentdesigns and from mud surface deposits of large experimentalenclosures (Lund Tubes) were monitored during 1978 and are analyzedin relation to the vertical and temporal distribution of tendominant phytoplankton populations. Sedimentation accounts fordiffering proportions of the total loss of biomass for differentalgae: between 28 and 100% of diatoms; 15–95% of Eudorina;<4% of populations of small algae (spp. ofAnkyra, Chromulina,Cryptomonas). Rates of diatom loss are also derived from thecomparison of net rates of change (k_n) and the silica uptake-derivedgrowth rate (k¹); intrinsic sinking behaviour may be specificallyregulated in relation to growth conditions. Implications inthe calculation of sedimentary losses and their impact uponthe seasonal periodicity of phytoplankton are briefly discussed.     

Generation or multiple genetic specificities: origin of genetic polymorphism through gene regulation

Summary Based on results of mutation studies in the fungus Schizophyllum commune, a new mechanism of the origin of genetic polymorphism is proposed. This may explain the intractable problems of the rise of multiple allelism controlling incompatibility in plants and the wide array of antibody diversity controlling immunity reaction in animals.Based on a lecture given at a joint meeting of the Mendelian Society of Lund and the Institute of Genetics, Lund, on 6th October, 1975, The author is grateful to Prof. A. Muntzing and Prof. A. Lundqvist for the invitation, and for the kindness and hospitality shown to him during his brief visit to Lund. This lecture formed a part of a lecture tour of Europe organized under the auspices of the Commission of European Communities, Brussells, and Association EURATOM-ITAL, Wageningen. The author is grateful to Dr. D. de Nettancourt (E.C.) and Dr. D. de Zeeuw (E.I.) for the kind invitation and financial support which made this memorable visit possible.     

A comparison of confidence interval methods for the intraclass correlation coefficient

Different methods of obtaining confidence intervals for the intraclass correlation coefficient rho in the unbalanced one-way random-effects model are investigated, focusing on applications to family studies. Methods based on simple modifications of formulas for the case of equal group sizes are found to provide adequate coverage at small to moderate values of rho. A method based on the large-sample standard error of the sample intraclass correlation, as derived by Smith (1956, Annals of Human Genetics 21, 363-373), is shown to provide consistently good coverage at all values of rho. A method proposed by Thomas and Hultquist (1978, Annals of Statistics 6, 582-587) also provides consistently good coverage, but generates mean interval widths substantially greater than those generated by Smith's method at values of rho likely to arise in practice.     

Claude Bourgelat and the creation of the first veterinary schools

The first veterinary school in the world was created in Lyon in 1761 by an equerry, Claude Bourgelat (1712-1779), a man renowned for his skill in horsemanship and horse medicine, a man fully able to understand the issues of his time. Aware of the scope of the physiocratic movement and of the need to improve the health of farm animals, he was able to understand the expectations of Henri-Léonard Bertin, Minister of King Louis XV, in proposing the creation of an establishment, breaking with traditional farriery. The creation of the Veterinary School of Lyon would mark a milestone: the consideration of livestock and the establishment of a profession, based on a scientific approach applied to all species. His relations, his communication skills, his European reputation and the opening of the first two schools to foreign students have ensured dissemination of this renewed vision throughout Europe, and provided these schools and their creator with a reputation that they still retain today.     

水杉的核型研究

本文观察了水杉的染色体,确定2n=22,核型公式为K(2n)=22m(2SAT),全具中着丝点,有一对随体。第8、10、11号染色体具“长着丝点区域”。属“1A”型,与北美红杉-AA的核型非常相近,可能是它的一个亲本种的直接后裔。     

5S-RNA genes of barley are located on the second chromosome

Summary The genes coding for 5S RNA in barley were cloned, sequenced, and their cluster was assigned to chromosome 2 using wheat-barley chromosome addition lines. High-resolution gel-electrophoresis of DNA and subsequent hybridization revealed new details of the organization of 5S DNA both in wheat and barley. The in situ hybridization of the cloned 5S gene with triploid endosperm nuclei also suggests that these genes are located in a single locus.On leave from: Department of Plant Breeding and Genetics, College of Agriculture, Orissa University of Agriculture & Technology, Bhubaneswar-751003, India     

Selection and Endpoint Distribution of Bacterial Inversion Mutations

This paper describes the isolation and characterization of spontaneous inversion mutants of Salmonella typhimurium. The mutants are selected by demanding that an unexpressed hisD gene acquire a new promoter. Chromosome rearrangements that juxtapose the hisD gene and a foreign promoter are obtained by this selection. Although a number of inversions are found, the frequency was lower than expected. The breakpoint of these inversions are not distributed randomly either in the his operon or on the chromosome. The his breakpoint lies in the hisG-hisD intercistronic region, a sequence known to occur at several places on the bacterial chromosome. In most of the inversions, the 'non-his' breakpoint lies across the chromosome, so that the inverted region includes the origin or terminus of DNA replication. The significance of these results is discussed.     

Interstitial telomere repeats as markers of evolutionary changes in the mammalian karyotype: human chromosome 2

Telomer repeats represented by hexamer (TTAGGG)n at chromosome termini are required for correct function and chromosome stability. At the same time, interstitial telomer sequence (ITS) located far from the chromosome ends are known for several mammalian genomes, including the human genome. It is assumed that these repeats mark the points of fusion or other chromosome reconstructions of ancestors. Exact localization of all interstitial telomer sequences in the genome could greatly improve our understanding of the mechanism of karyotype evolution and species origin. We have developed a software for a search of interstitial telomer sequences in complete sequences of mammalian genomes. We have demonstrated the evolutionary significance of repeats by an example of human chromosome 2. The results and supplementary materials are available at the site of the Institute of Cytology and Genetics: http://www.bionet.nsc.ru/labs/theorylabmain/orlov/telomere/.     

Isochromosome for the long arm of the Y in an infertile male

Summary A 37-year-old man investigated for infertility had bilateral atrophic testes. Cytogenetic investigations revealed a chromosome complement of 45,XO/46,Xi(Yq)/46,XY. Mechanisms for the origin of the i(Yq) are considered, and the relation of his chromosome constitution to his infertility and hypogonadism are discussed.     

The current view for the silencing of the spindle assembly checkpoint

Chromosome bipolar attachment is achieved when sister kinetochores are attached by microtubules emanating from opposite spindle poles, and this process is essential for faithful chromosome segregation during anaphase. A fundamental question in cell biology is how cells ensure that chromosome segregation only occurs after bipolar attachment. It is well documented that unattached kinetochores activate the spindle assembly checkpoint (SAC) to delay chromosome segregation. Therefore, the silencing of the SAC is thought to trigger anaphase onset, but how correct chromosome attachment is coupled with SAC silencing and the subsequent anaphase onset is poorly understood. The establishment of chromosome bipolar attachment not only results in the occupancy of kinetochores by microtubules but also applies tension on sister kinetochores. A long-standing debate is whether the kinetochore attachment (occupancy) or the tension silences the SAC. Recent work in budding yeast reveals the SAC silencing network SSN that prevents SAC silencing prior to tension generation at kinetochores. Therefore, this signaling pathway ensures that SAC silencing and the subsequent anaphase onset occur only after chromosome bipolar attachment applies tension on chromosomes. This review will summarize the recent advances in the understanding of the SAC silencing process.     

Four Children and Yale: The Making of a Human Geneticist: The Grover Powers Lecture 2014

Dr. Leon E. Rosenberg delivered the following presentation as the Grover Powers Lecturer on May 14, 2014, which served as the focal point of his return to his “adult home” as a Visiting Professor in the Department of Pediatrics. Grover F. Powers, MD, was one of the most influential figures in American Pediatrics and certainly the leader who created the modern Department of Pediatrics at Yale when he was recruited in 1921 from Johns Hopkins and then served as its second chairman from 1927 to 1951. Dr. Powers was an astute clinician and compassionate physician and fostered and shaped the careers of countless professors, chairs, and outstanding pediatricians throughout the country. This lectureship has continued yearly since it first honored Dr. Powers in 1956. The selection of Dr. Rosenberg for this honor recognizes his seminal role at Yale and throughout the world in the fostering and cultivating of the field of human genetics. Dr. Rosenberg served as the inaugural Chief of a joint Division of Medical Genetics in the Departments of Pediatrics and Internal Medicine; he became Chair when this attained Departmental status. Then he served as Dean of the Medical School from 1984 to 1991, before he became President of the Pharmaceutical Research Institute at Bristol-Myers Squibb and later Senior Molecular Biologist and Professor at Princeton University, until his recent retirement. Dr. Rosenberg has received numerous honors that include the Borden Award from the American Academy of Pediatrics, the McKusick Leadership Award from the American Society for Human Genetics, and election to the Institute of Medicine and the National Academy of Sciences.     

中国芦荟染色体核型分析

以中国芦荟为试验材料,按常规染色体压片法,观察中期分裂相并进行显微摄影。染色体类型按Ｌｅｖａｎ方法分类,其核型为Ｋ（２ｎ）＝６ｓｔ＋８ｓｍ。