Biomechanical aspects of underwater acoustics with a special reference to hydrobiology

Some biomechanical aspects of the acoustical behaviour of underwater animals is discussed here. We have avoided mathematical complexities.     

Monoamines in the hypothalamo-hypophyseal system of the mouse with special reference to the ontogenetic aspects

Summary An accumulation of monoamines is found in the adult eminentia mediana and infundibular stem, close to the capillaries of the primary plexus, where they seem to be stored mainly in closely packed delicate varicose fibres, often with swollen endings, droplets. The first traces of monoamines are visible in the embryonic eminentia of fetuses from the last three days of the gestation period, but typical monoamine-containing fibre endings close to the primary plexus capillaries in zona externa are not found until towards the end of the first post-natal week. The adult condition is attained two weeks later. Nearly all cells in the adult pars intermedia show a specific yellowish fluorescence whose intensity shows a wide individual variation. Such fluorescent cells are sometimes present in the intermedia of the new-born. In some but not all adult specimens, a fluorescent varicose fibre system is visible. Fluorescent fibres were first observed in the intermedia of the new-born. Fluorescent fibres are visible in n. arcuatus and n. paraventricularis in the fetus at the 16th day of the gestation period. Nerve cell bodies storing visible amounts of monoamines are found in n. arcuatus, n. periventricularis anterior, and n. premammillaris ventralis of the adult. This amine storing activity is first visible in n. arcuatus of the embryo at the 17th day of the gestation period. The adult condition of these cells is reached during the first postnatal week.     

Methodological aspects on immunohistochemistry in dermatology with special reference to neuronal markers

Summary In an attempt to optimize the immunohistochemical procedure for visualizing neuronal markers, such as neuropeptides, in the human skin, different alternatives in all steps of the process were compared. We have studied the influence of type of immunohistochemical method, the biopsy technique, including the size of the punch biopsy, anaesthesia, the choice of fixative and the time of fixation, the storage process, the sectioning parameters, incubation procedure, the type of fluorophore-conjugated antibody and its dilution, mounting and storage, and, finally, microscopical examination.The following procedure was found to give the best result: punch biopsies of 3 mm, taken under local anaesthesia using lidocaine injected into the dermis-subcutis at the place of biopsy; fixation by a buffered 10% formalin solution containing 14% of saturated picric acid for 2 h at 4°C; storage in 10% sucrose buffer for at least 24 h up to 1 month at 4°C or deep-frozen to -70°C for 2 months (with only a minor structural deterioration); cryostat sectioning of the biopsies with a section thickness of 14 m and with the cutting edge perpendicular to the skin surface; rhodamine (TRITC)-conjugated, instead of fluorescein-isothiocyanate (FITC)-conjugated, secondary antiserum, since it gives a lower background fluorescence; and for the incubation and mounting procedures, our standard laboratory routines were applied. The result is an optimal indirect immunofluorescence technique, to be applied in dermatology. We also found that biopsies taken under local anaesthesia with chlorethyl spray lost almost all immunofluorescence for several neuronal markers in the epidermis-upper dermis.     

Visceroatrial heterotaxy syndrome in the NOD mouse with special reference to atrial situs

Following the onset of diabetes mellitus (DM) in the NOD mouse, diabetic dams have many offspring with severe anomalies, especially with visceroatrial heterotaxy syndrome. The purpose of the present study is to analyze this syndrome with special reference to atrial situs. The fetuses from a colony of NOD mice in our laboratory were divided into two study groups: Group A included fetuses from dams before the onset of DM and group B included fetuses from dams with overt DM before day 8 of pregnancy. The fetuses which had cardiac anomalies with viscero-atrial heterotaxy were classified into four subtypes according to the atrial morphology, i.e., "incomplete situs solitus" (or solitus-like), "incomplete situs inversus" (inversus-like), right isomerism, and left isomerism. Group A (671 fetuses) included only one case with right isomerism (0.15%) and four cases with left isomerism (0.6%). Group B (158 fetuses) had 57 fetuses with heterotaxy syndrome (36.1%), including 20 cases with solitus-like, 6 with inversus-like, 30 with right isomerism, and one with left isomerism. A tendency for right isomerism to occur was found in fetuses with solitus-like and inversus-like anomalies. These results show that the maternal DM in this mouse had an influence upon the morphological mechanism determining right isomerism of visceroatrial heterotaxy syndrome. Thus this syndrome in the NOD mouse is equivalent to asplenia in humans, and it may be useful in elucidating the mechanism of the human syndrome.     

Further segregation analysis of the fragile X syndrome with special reference to transmitting males

Summary A new series of 96 pedigrees with the fra(X) syndrome was analysed using complex segregation analysis with pointers, defining affection as any degree of mental impairment. These families were found to exhibit the same segregation pattern as the first series of 110 pedigrees (Sherman et al. 1984). The best estimate for penetrance of mental impairment in males was 79% and in females was 35% for the combined data. Again, there was little evidence for sporadic cases among affected males.Many more intellectually normal transmitting males have been observed since the existence of such males and the concomitant need to investigate the paternal side of pedigrees was recognized. On further investigation of all 206 pedigrees from the old and new data sets, the sibships of nonexpressing males appeared to be different from those of expressing males. Our analysis, using mental impairment as the phenotype, suggested that obligate carrier mothers and daughters of intellectually normal transmitting males are rarely, if ever, mentally impaired and that the sibs of transmitting males are much less likely to be retarded than the sibs of mentally impaired males. Though mothers and daughters of transmitting males are similar in phenotype, the expression of the gene in their offspring appears to be different: the penetrance of mental impairment is higher in offspring of intellectually normal daughters of transmitting males than in offspring of intellectually normal mothers of transmitting males. The implications of these observations for genetic counseling and for genetic models of the fra(X) syndrome are discussed.     

Age determination of pre- and postnatal skeletons with special reference to current methodological aspects]

From the remains of ten fetal and neonatal skeletons the standard methods of age estimation by means of dental and osseous criteria as well as diaphyseal length were applied and discussed. The ratio of long bone lengths and change of proportions during the first and second half of pregnancy is a useful indicator for the stage of maturation.     

Ecology of siderophores with special reference to the fungi

Ecology of siderophores, as described in the present review, analyzes the factors that allow the production and function of siderophores under various environmental conditions. Microorganisms that excrete siderophores are able to grow in natural low-iron environments by extracting residual iron from insoluble iron hydroxides, protein-bound iron or from other iron chelates. Compared to the predominantly mobile bacteria, the fungi represent mostly immobile microorganisms that rely on local nutrient concentrations. Feeding the immobile is a general strategy of fungi and plants, which depend on the local nutrient resources. This also applies to iron nutrition, which can be improved by excretion of siderophores. Most fungi produce a variety of different siderophores, which cover a wide range of physico-chemical properties in order to overcome adverse local conditions of iron solubility. Resource zones will be temporally and spatially dynamic which eventually results in conidiospore production, transport to new places and outgrow of mycelia from conidiospores. Typically, extracellular and intracellular siderophores exist in fungi which function either in transport or storage of ferric iron. Consequently, extracelluar and intracellular reduction of siderophores may occur depending on the fungal strain, although in most fungi transport of the intact siderophore iron complex has been observed. Regulation of siderophore biosynthesis is essential in fungi and allows an economic use of siderophores and metabolic resources. Finally, the chemical stability of fungal siderophores is an important aspect of microbial life in soil and in the rhizosphere. Thus, insolubility of iron in the environment is counteracted by dissolution and chelation through organic acids and siderophores by various fungi.     

Cryopreservation of bacteria with special reference to anaerobes

The author is with the DSM-Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH, Mascheroder Weg 1b, D-3300 Braunschweig, Germany.