Nadine Dobrovolskaïa-Zavadskaïa and the dawn of developmental genetics

In one of the first genetic screens aimed at identifying induced developmental mutants, Nadine Dobrovolskaïa‐Zavadskaïa, working at the Pasteur Laboratory in the 1920s, isolated and characterized a mutation affecting Brachyury, a gene that regulates tail and axial development in the mouse. Dobrovolskaïa‐Zavadskaïa's analysis of Brachyury and other mutations affecting tail development were among the earliest attempts to link gene action with a tissue‐specific developmental process in a vertebrate. Her analyses of genes that interacted with Brachyury led to the discovery of the t‐haplotype chromosome of mouse. After 70 years, Brachyury and the multiple genes with which it interacts continue to occupy a prominent focus in developmental biology research. A goal of this review is to identify the contributions that Dobrovolskaïa‐Zavadskaïa made to our current thinking about Brachyury and how she helped to shape the dawn of the field of developmental genetics. BioEssays 23:365–371, 2001. © 2001 John Wiley & Sons, Inc.     

Morphologie des spermatozoïdes

Spermatozoa morphology is one of the qualitative characteristics of spermatogenesis. However, because of both the variations in the definition of normal morphology and the existence of different kinds of sperm abnormalities as well as the use of various techniques of morphology assessment, such a parameter is poorly used in usual laboratory work. Morphological sperm anomalies can be from testicular or post-testicular origines, while the latter is still unproved. The causes of such anomalies are either from genetic origines, but in these cases any spermatozoa demonstrate this anomaly, or due to an endogenous factor with varicocele the most usually quoted but unproved pathology, But exogenous factors, either chemical such as drugs and pesticides or physical such as heat, are also responsible for morphological sperm anomalies. Analysis of sperm morphology is indicative of both the testicular health status (in cases of occupational exposure to chemical or physical toxics) and the fertility potential since morphology is correlated to sperm motility and involved in fertilization through the acrosome reaction.     

Alcaloïdes chez les capparidaceae

Alkaloids were isolated from leaves of 33 of 36 species and l-stachydrine and l-3-hydroxystachydrine were the major components present. These alkaloids characterize the family Capparidaceae in the same way as do the glucosinolates.     

Le test post coïtal

The post-coital test (PCT) is an important step in any investigation into a couple's fertility. It is a mean of appraising sperm/mucous interaction after intercourse. It is a simple test but must be carried out under specific clinical conditions. The stretchiness of endocervical mucus is the best characteristic by which to judge the quality of the mucus. The time-lag between intercourse and the test may vary and there is no need for 2 or 3 days of sexual abstinence prior to the test, which makes the PCT less of a constraint. Like most fertility-related investigations, the information it provides is only relative. In terms of prognosis, it is important for the results to be good. However, it is an invaluable part of a couple's first-line test. This articles gives details of the conditions under which we carry out the test.     

Evaluation morphologique des spermatozoïdes

Semen analysis, as defined by World Health Organisation (WHO), is a fundamental step in the work-up of infertile couples. Spermatozoa morphology has been recognised as the best predictive factor in natural fertility, and in intrauterine insemination and classicalin vitro fertilisation. Ultrastructural spermatozoa abnormalities are the only sperm alterations likely to influence the outcome of ICSI. However, these abnormalities cannot be detected by conventional microscopy (¥100 or ¥200–400). Bartoov et al. (2002) developed a real-time spermatozoa observation system using a ¥6600 magnification called MSOME (Magnification Motile Sperm Morphology Examination). Spermatozoa abnormalities detected with this technique are vacuoles localised on spermatozoa heads with variable number, size and site (nucleus or acrosome). Spermatozoa evaluation using MSOME could be performed to predict the probability of fertilisation by these spermatozoa either spontaneously or after assisted reproductive technology.     

Accessing naïve human pluripotency

Pluripotency manifests during mammalian development through formation of the epiblast, founder tissue of the embryo proper. Rodent pluripotent stem cells can be considered as two distinct states: na?ve and primed. Na?ve pluripotent stem cell lines are distinguished from primed cells by self-renewal in response to LIF signaling and MEK/GSK3 inhibition (LIF/2i conditions) and two active X chromosomes in female cells. In rodent cells, the na?ve pluripotent state may be accessed through at least three routes: explantation of the inner cell mass, somatic cell reprogramming by ectopic Oct4, Sox2, Klf4, and C-myc, and direct reversion of primed post-implantation-associated epiblast stem cells (EpiSCs). In contrast to their rodent counterparts, human embryonic stem cells and induced pluripotent stem cells more closely resemble rodent primed EpiSCs. A critical question is whether na?ve human pluripotent stem cells with bona fide features of both a pluripotent state and na?ve-specific features can be obtained. In this review, we outline current understanding of the differences between these pluripotent states in mice, new perspectives on the origins of na?ve pluripotency in rodents, and recent attempts to apply the rodent paradigm to capture na?ve pluripotency in human cells. Unraveling how to stably induce na?ve pluripotency in human cells will influence the full realization of human pluripotent stem cell biology and medicine.     

Alcaloïdes du Pandaca ochrascens

From leaves and root bark of Pandaca ochrascens ten alkaloids were isolated: apparicine, akuammicine, dehydro-19,20 condylocarpine, akuammidine, epi-16 dehydro-14,15 vincamine, ibogaine, iboluteine, ibogaline and also two new alkaloids, epi-19 ibogaine or (19R) 19-hydroxyibogaine and epi-19 iboxygaline or (19R) 19-hydroxyibogaline. The absolute configuration at C₁₉ of these new alkaloids and other alkaloids hydroxylated on 19 of the Iboga type is discussed.     

Estrogènes et spermatozoïdes

Aromatase is the terminal enzyme responsible for estrogen biosynthesis; it is present in the endoplasmic reticulum membrane of steroidogenic cells in vertebrates. This enzyme functions with the ubiquitous reductase as the electron donor. The aromatase gene is unique and its expression is regulated in a tissue and more precisely in a cell-specific fashion via the alternative use of several promoters located in the first exons. This enzymatic complex is generally involved in development, reproduction, sexual differentiation and behaviour, but also in bone and lipid metabolism, brain functions and diseases such as breast and testicular tumors. The aromatase gene expression and its transduction in a fully active protein in testicular somatic cells and germ cells together with the widespread distribution of estrogen receptors (ERα & β) in the testis and the genital tract of the male, are clearly in favor of a physiological role for estrogens in the spermatogenesis processings especialy in sperm maturation. Therefore, we begin to understand the physiopathological roles of the estrogens in males indeed, the aromatase deficiency is associated, with severe bone maturation problems and sterility in man. Conversely, it is also obvious that estrogens in excess are responsible of the impaired spermatogenesis. These female hormones (or the ratio androgens/estrogens) do play a physiological role in the development and maintenance of male gonadal functions and obviously, several steps are concerned especially the sperm production and maturation.     

Tomographie sténopéïque au 99mTc-MIBI dans l’hyperparathyroïdie primaire

PurposeThis prospective study was conducted to determine the interest of ^99mTc-MIBI pinhole SPECT compared with conventional SPECT, planar scintigraphy and ultrasonography, for the preoperative localization of parathyroid lesions in primary hyperparathyroidism.MethodsFifty-one patients cured after surgery were studied. Pinhole SPECT was reconstructed with a dedicated OSEM algorithm. Scintigraphies were analyzed visually. A diagnostic confidence score (CS) was assigned to each procedure considering intensity and extrathyroidal location of suspected lesions and was defined as follows: 0 = negative, 1 = doubtful, 2 = moderately positive, 3 = positive.ResultsSurgery revealed 55 lesions. Sensitivity of ultrasonography, planar imaging, conventional SPECT and pinhole SPECT were respectively, 51, 76, 82 and 87%. Five glands were only detected by pinhole SPECT. Combination of ultrasonography, planar and pinhole SPECT showed the highest sensitivity (94.5%). The mean CS of the 55 pathologic glands was significantly higher with pinhole SPECT compared with planar imaging and conventional SPECT (p < 0.0001). Compared with planar imaging and conventional SPECT, pinhole SPECT increased CS for 42 and 53% of parathyroid lesions, respectively, and contributed to markedly reduce the number of uncertain results. Nevertheless, planar imaging and ultrasonography were useful to analyze thyroid morphology and to detect some ectopic glands.ConclusionThe use of pinhole SPECT increases sensitivity and CS of scintigraphy. Combination of ultrasonography, planar and pinhole SPECT appears the optimal preoperative imaging procedure in primary hyperparathyroidism.     

La vitalité des spermatozoïdes

Most of the numerous techniques used to assess sperm viability only have research applications, while only two classical tests, i.e. eosin-Y and hypo-osmotic swelling test (HOST), are currently used in routine sperm analysis to determine the percentage of viable sperm. A viability rate below 50% of living sperm defines necrozoospermia, a condition whose clinical significance is fairly difficult to assess as the mechanisms of sperm cell death are still poorly understood. However, even when a precise cause for necrozoospermia cannot be identified, abnormal viability requires further andrological investigations with particular emphasis on clinical and laboratory signs of chronic infection of the male reproductive tract. Intracytoplasmic sperm injection (ICSI) can yield very good pregnancy rates, even in couples with the most severe forms of male infertility. However, when no motile sperm are available after sperm preparation, the outcome of ICSI is seriously impaired, probably because of a high risk of injecting dead sperm. In these patients, sperm viability could therefore be assessed by the hypo-osmotic swelling test in order to select only viable sperm for ICSI. However, the long incubation time of sperm in the hypo-osmotic solution, as recommended in the classical HOST procedure, has been shown to be detrimental to the spermatozoa. A single sperm test able to assess the viability of each individual spermatozoon within microdroplets covered by mineral oil therefore seems to be preferable. This selection procedure is less suitable in the case of immotile frozen-thawed sperm, as viability does not appear to be reliably predicted by HOST in cryopreserved sperm. Examination of sperm viability now also evaluates programmed cell death or apoptosis, as apoptotic alterations can be detected in spermatozoa by several techniques. The percentage of apoptotic sperm is correlated with deficient sperm parameters and poor outcome of assisted reproductive techniques. More effective selection procedures are therefore needed in order to identify spermatozoa not only with intact membranes but also with an intact genome to be used for ICSI.     

Cooperative hunting roles among taï chimpanzees

All known chimpanzee populations have been observed to hunt small mammals for meat. Detailed observations have shown, however, that hunting strategies differ considerably between populations, with some merely collecting prey that happens to pass by while others hunt in coordinated groups to chase fast-moving prey. Of all known populations, Taï chimpanzees exhibit the highest level of cooperation when hunting. Some of the group hunting roles require elaborate coordination with other hunters as well as precise anticipation of the movements of the prey. The meat-sharing rules observed in this community guarantee the largest share of the meat to hunters who perform the most important roles leading to a capture. The learning time of such hunting roles is sometimes especially long. Taï chimpanzee males begin hunting monkeys at about age 10. The hunters’ progress in learning the more sophisticated hunting roles is clearly correlated with age; only after 20 years of practice are they able to perform them reliably. This lengthy learning period has also been shown in some hunter-gatherer societies and confirms the special challenge that hunting represents.