Some contributions of I.E. Purkyn? to the visual physiology

In the research of binocular vision J. E. Purkyn? pointed out the role of retinal corresponding areas. He observed binocular interaction of pressure phosphenes elicited in them and the fusion of images projected on the corresponding foveal areas even in eyes with artificial divergency. For the first time he proposed the examination of visual fields (perimetry) in several planes and he also introduced the colour perimetry. Purkyn? analyzed profoundly the different functions of direct (foveal) and indirect (peripheral) vision. In indirect vision he anticipated the modern concept of the useful field of view. Of fundamental importance was Purkyn?'s research of the strategy and different types of ocular movements. In analysis of motion perception, he evolved the hypothesis of "general sense of space" which is very close to modern feed-back conception of "corollary discharge".     

Description of Oerskovia gen. n. to Harbor ?rskov's Motile Nocardia

The genus Oerskovia is proposed to harbor actinomycetes forming an extensively branched substrate mycelium which usually breaks up into motile elements. Cell wall preparations contain major amounts of lysine and galactose. Aspartic acid is often present in major amounts. Aerial mycelium is not formed. Gram reaction and catalase production are positive. The type species is Oerskovia turbata comb. n.     

Microbial transformations of natural antitumor agents. 23. conversion of withaferin-A to 12β- and 15β-hydroxy derivatives of withaferin-A.

Microbial transformation experiments were conducted with the antitumor lactone withaferin-A. $\text{Cunninghamella elegans}$ NRRL 1393 transformed withaferin-A ($\text{1a}$) to 15β-hydroxywithaferin-A ($\text{2a}$) and 12β-hydroxywithaferin-A ($\text{3a}$). The hydroxylated metabolites were isolated by solvent extraction and were purified by column and thin-layer chromatography. Structures of the hydroxylated metabolites were determined by protonand carbon-13 NMR, IR and mass spectral analyses, and by the preparation of acylated derivatives. Compounds $\text{2a}$ and $\text{3a}$ inhibited the growth and biochemical functions of $\text{in vitro}$ grown P-388 lymphocytic leukemic cells.     

Resistance of M. leprae to Quinolones: A Question of Relativity?

Multidrug resistant leprosy, defined as resistance to rifampin, dapsone and fluoroquinolones (FQ), has been described in Mycobacterium leprae. However, the in vivo impact of fluoroquinolone resistance, mainly mediated by mutations in DNA gyrase (GyrA₂GyrB₂), has not been precisely assessed. Our objective was to measure the impact of a DNA gyrase mutation whose implication in fluoroquinolone resistance has been previously demonstrated through biochemical studies, on the in vivo activity of 3 fluoroquinolones: ofloxacin, moxifloxacin and garenoxacin.

Methodology/Principal Findings

We used the proportional bactericidal method. 210 four-week-old immunodeficient female Nude mice (NMRI-Foxn1^nu/Foxn1^nu) were inoculated in the left hind footpad with 0.03 ml of bacterial suspension containing 5×10³, 5×10², 5×10¹, and 5×10⁰ M. leprae AFB organisms of strain Hoshizuka-4 which is a multidrug resistant strain harboring a GyrA A91V substitution. An additional subgroup of 10 mice was inoculated with 5×10⁻¹ bacilli in the untreated control group. The day after inoculation, subgroups of mice were treated with a single dose of ofloxacin, moxifloxacin, garenoxacin or clarithromycin at 150 mg/kg dosing. 12 months later mice were sacrificed and M. leprae bacilli were numbered in the footpad. The results from the untreated control group indicated that the infective inoculum contained 23% of viable M. leprae. The results from the moxifloxacin and garenoxacin groups indicated that a single dose of these drugs reduced the percentage of viable M. leprae by 90%, similarly to the reduction observed after a single dose of the positive control drug clarithromycin. Conversely, ofloxacin was less active than clarithromycin.

Conclusion/Significance

DNA gyrase mutation is not always synonymous of lack of in vivo fluoroquinolone activity in M. leprae. As for M. tuberculosis, in vivo studies allow to measure residual antibiotic activity in case of target mutations in M. leprae.     

Application of AFLP™-based molecular markers to breeding of Populus spp.

Molecular marker technologies have eased and potentiated genetic analysis of plants and have become an extremely useful tool in forest tree breeding. The information provided by molecular markers has made it possible to acquire further knowledge about the structure and organization of plant genomes as well as about the evolution of these plant genomes through phylogenetic analysis. Using Populus spp. as a model tree, this paper aims at showing and discussing the possible applications of AFLP, a high-density DNA marker technology developed by Keygene N.V. (Wageningen, The Netherlands). Applications include: (i) AFLP analysis of the disease resistance against Melampsora larici-populina using bulked-segregant analysis, (ii) AFLP fingerprinting for identification and taxonomic analysis of individual trees, and (iii) AFLP-based mapping strategies in Populus.Abbreviations AFLP amplified fragment length polymorphism - RFLP restriction fragment length polymorphism - PCR polymerase chain reaction - QTL quantitative trait loci - RAPD random amplified polymorphic DNA     

Application of in vitro pollination of opened ovaries to obtain Brassica oleracea L. × B. rapa L. hybrids

This study presents the results of experiments concerning: (1) interspecific hybridization of Brassica oleracea × Brassica rapa via application of in vitro placental pollination and (2) embryological analysis of the process of resynthesis of Brassica napus. In order to overcome certain stigma/style barriers, B. rapa pollen was placed in vitro on an opened B. oleracea ovary (with style removed). Pollinated ovaries were cultured on Murashige and Skoog (MS) medium. After 24-d culture, the developing embryos were isolated from immature seeds and transferred onto MS medium supplemented with 0.47 μM kinetin, 0.49 μM 1-naphthaleneacetic acid, and 10% (v/v) coconut water. When the embryos had turned green, they were immediately placed onto MS medium with 100 μM kinetin. After development of the seedling, plantlets were transferred to soil. Chromosome doubling was achieved after another week. Cytometric analysis of nuclear DNA confirmed the hybrid nature of the plants. Resynthesis of B. napus can be performed through interspecific hybridization of B. oleracea × B. rapa followed by embryo rescue and genome doubling.     

Kinds of glycosidase and properties of β-N-acetylglucosaminidase bound to mycelia of streptomyces sp.

An extract liberated from mycelia of the L-13 strain of Streptomyces by 0.2 M phosphate buffer, pH 6.5, contained β-N-acetylglucosaminidase, β-N-acetylgalactosaminidase and a little α-glucosidase. On chromatofocusin, the isoelectric point of β-N-acetylglucosaminidase was around pH 8.1. The enzyme prepared thus was homogeneous, and had both β-N-acetylglucosaminidase and β-N-acetlygalactosaminidase activities. The β-N-acetylglucosaminidase was most active at pH 6.0 and stable between pH 4 to 8. The K_m value for p-nitrophenyl β-N-acetylglucosaminide was 0.25 mM. N-Acetylglucosaminolactone was the most potent inhibitor tested.     

Resistance of α-globulin fromSesamum indicum L. to proteases in relationship to its structure

α-Globulin, the high-molecular-weight protein fraction fromSesamum indicum L., was hydrolyzed to low-molecular-weight protein and peptides by pepsin, while its resistance to hydrolysis by group-specific enzymes, trypsin or α-chymotrypsin, was very high. The protein showed definite structural changes after proteolysis, especially after peptic hydrolysis, as evidenced from various biophysical data. The sedimentation velocity pattern of α-globulin hydrolyzed by trypsin or α-chymotrypsin indicated reduction in the percentage of 11S component, while the pepsinhydrolyzed sample was devoid of any 11S component, indicating the absence of a native protein molecule. The fluorescence emission spectra of the various hydrolyzed α-globulin showed a red shift in the fluorescence emission maximum. The red shift was maximum with α-globulin hydrolyzed by pepsin and minimum with the trypsin-hydrolyzed sample. The far-ultraviolet-circular dichroic measurements indicated that most of the ordered structure of α-globulin was absent after pepsin hydrolysis, while after trypsin and chymotrypsin hydrolysis conformational changes were less.     

Contributions to the mathematical theory of epidemics—II. The problem of endemicity

(1) A mathematical investigation has been made of the prevalence of a disease in a population from which certain individuals are being removed as the result of the disease, whilst fresh individuals are being introduced as the result of birth or immigration. Allowance is made for the effects of the immunity produced as the result of an attack of the disease, but the effect of deaths from other causes is not taken into account, and the action of the disease is supposed to be independent of the age of the individual. (2) As a special case of the above, results have been obtained for a closed population in which no deaths occur and to which no fresh individuals are added, but in which the individuals after being infected acquire immunity, and then may be again infected. A threshold density of population exists analogous to that described in the previous paper, which is such that no disease can exist in a population, the density of which is below the threshold. (3) In other special cases investigated when either immigration or birth is operative in the supply of fresh individuals, as well as in the general case, only one steady state of disease is possible. To reach this state the population must be of a certain density which will be determined by the functions characterizing the infectivity, morbidity, etc., of the disease. (4) Increase of the immigration rate or of the birth-rate results in an increase in the rate of infection of the healthy individuals and also in the percentage rate of infection, the percentage of sick, and in the percentage of mortality from the disease. This result is, of course, a necessary consequence of our assumption that the disease is the only cause of death. (5) More particular results have been obtained by substituting constants in the place of the undetermined functions assumed in the general theory. Further, under these conditions the nature of the steady states has been more fully investigated and it has been shown that in all cases, except one, the steady states are stable ones. In the exception, a disturbance would result in purely periodic oscillations about the steady state.     

M?ssbauer studies of cytochrome c-551. Intrinsic heterogeneity related to g-strain.

The M?ssbauer spectra of oxidized and reduced cytochrome c-551 from Pseudomonas aeruginosa are analyzed. Excess broadening is observed in the 4.2 K spectra of oxidized c-551 which is consistent with a Gaussian distribution of the crystal field parameters delta and R as inferred from the g-strain model of EPR line shapes.     

Calcitonin—C.N.S. action to control the pattern of intestinal motility in rats

Synthetic calcitonin injected into the lateral ventricles (ICV) of rats at picomolar concentration restores the “fasted” motility pattern of the small intestine in fed rats at doses as low as 0.083 picomoles. This effect which appeared in less than 5 min and persisted at least 2 hours for 0.83 picomole, was blocked by a previous intraventricular administration of 10 μg of calcium gluconate. At 0.83 picomole ICV, calcitonin also suppressed the disruption of the “fasted” pattern induced by intravenous infusion of Pentagastrin (6 μg·kg^?1·h^?1) but not that induced by insulin (0.5 U·kg^?1). These findings support the hypothesis that calcitonin acts centrally to control the pattern of intestinal motility by inhibiting the digestive influences responsible for the “fed” pattern. All of these peripheral influences are mediated by a Ca⁺⁺ sensitive central structure.     

The 125th anniversary of the first postulation of the soil origin of endophytic bacteria – a tribute to M.L.V. Galippe

Aims

In spite of the important role played by herbivory in plant community structure and the fact that it constitutes one of the most important ecological disturbance processes in the dynamics of both natural and anthropic systems, few studies have concentrated on the consequences of browsing on vegetation spatial patterns. The main objective of this study was to examine the role of domestic livestock pressure in the spatial distribution pattern and interspecific competition of two sand dune shrubs: Retama monosperma and the endangered species Thymus carnosus.

Methods

We compared three areas featuring different intensities of livestock pressure. Two 25 × 25 m plots were established in each study area, and the crown heights, diameters and x, y coordinates of every individual in each plot were recorded.

Results

Livestock activity produced a considerable effect, not only on plant cover and size (larger and higher crowns of both species in non herbivory plots) but also on spatial pattern. Whereas light herbivory lead to a random spatial pattern for both species, high herbivory resulted in a repulsion one.

Conclusions

Under high and no livestock pressure, T. carnosus is displaced by R. monosperma, creating a repulsion point pattern distribution between the two species. However, when livestock disturbance was low, our data reveal relatively higher T. carnosus cover values than in the other livestock pressure scenarios, along with a random distribution pattern.     

Biological Time-Related Changes in Tolerance of Male Mice to Hypoxia—II. Orcadian Rhythm of Lysosomal Susceptibility to Hypoxia

Circadian variations of mouse liver, brain and heart lysosomal susceptibility to hypoxia were investigated. Lysosomal disruption during hypoxia was estimated on the basis of the following measurements: changes in percentage free activity of β-galactosidase and acid phosphatase, tissue loss of both lysosomal enzymes and accumulation of serum β-galactosidase. When exposure to hypoxia took place at the end of the rest phase or at the beginning of the active phase, it was accompanied by maximum increase of percent free activity. This, presumably represents a diffusion of enzymes from lysosomes due to altered membrane permeability. However, hypoxia when occurring during the second part of the active phase and first part of the rest phase resulted in tissues loss of lysosomal enzymes and accumulation of serum lysosomal enzymes. This is believed to represent the release of lysosomal enzymes in bulk from damaged or ruptured lysosomal membranes.     

Electrophysiological and behavioural responses of the housefly to “sweet” volatiles of the flowers of Caralluma europaea (Guss.) N.E. Br.

In sapromyiophilous plants, up to date, long range attraction of fly pollinators has been thoroughly investigated and attributed to “fetid” floral compounds, while the “sweet” floral scent fraction has not been specifically investigated and its role has received little attention. The aim of the present study was to verify if terpenoids, which are the main compounds of the floral bouquet of Caralluma europaea, play a role in the attraction of its pollinator Musca domestica. Terpinolene, α-terpinene and linalool, described as the three main volatiles of the flowers of C. europaea, were evaluated in electrophysiological investigations and blends of these compounds as well as the whole fresh flowers were used in behavioural assays. Antennae of housefly adults showed positive dose-dependent responses to all the chemicals tested. Houseflies were attracted by the odour of the fresh flowers and by the reconstructed terpenoid blend at the dose of 100 μg. At the dose of 10 μg, the blend did not produce any attraction. The results of the present study support the hypothesis that terpinolene, α-terpinene and linalool emitted by C. europaea flowers are involved in pollinator attraction and demonstrate the importance of the “sweet” scent in this sapromyiophilous species.     

The sensitivity of embryogenic tissue of Picea omorika (Panč.) Purk. to antibiotics

In an attempt to develop a transformation procedure for somatic embryos of Picea omorika (Pan.) Purk. using Agrobacterium, the sensitivity of non-transformed embryogenic tissues of P. omorika to antibiotics was measured. Two groups of antibiotics were tested: antibiotics commonly used to eliminate Agrobacterium from tissue culture (carbenicillin and cefotaxime), and antibiotics for the selection of transformed tissue (kanamycin, paromomycin, neomycin and hygromycin). Carbenicillin (500 mg l^–1) reduced proliferation of P. omorika embryogenic tissue by 50% as compared to the control. Cefotaxime (500 mg l^–1) was less toxic to embryogenic tissue growth (93% of the control) and is thus more suitable for the elimination of A. tumefaciens from embryogenic tissue of P. omorika. Embryogenic tissue showed severe susceptibility to kanamycin and hygromycin. Induction of secondary embryogenesis was blocked by 10 mg l^–1 of kanamycin or 2 mg l^–1 of hygromycin. The aminoglycoside analogs of kanamycin, paromomycin and neomycin inhibited embryogenic tissue induction at concentrations of 5 and 100 mg l^–1, respectively. The higher tolerance of embryogenic tissue to neomycin indicated that of the antibiotics tested neomycin may be most useful for selection of nptII-transformed embryogenic tissue of Picea omorika.     

Transfer of seabed mining technology: A stumbling block to U.S. ratification of the law of the sea convention?

Abstract

The Law of the Sea Convention's provisionson the transfer of seabed technology are designed to translate into specific terms the general notions (adopted in the U. N.’s Declaration of Principles of 1970) that the resources of the seabed are the “common heritage”; of humankind and that the developing nations are to gain special benefits from the exploitation of these resources. Some developed nations—in particular, the United States—have argued that these provisions are unfair, because they deprive the multinational enterprises of the developed world of the competitive advantage they have gained from their substantial investment in research and development and their innovative capabilities.

The transfer of technology is not a new concept. It is a mechanism that has been used systematically by many developing countries to ensure that foreign investments will produce a lasting infrastructure for continued national development. Multinational enterprises have learned to accommodate national needs in this area, and technology‐transfer requirements for land‐based investments have not deterred investments in the developing world.

The technology‐transfer provisions in the Law of the Sea Convention are ambiguous in certain respects, but the Preparatory Conference should provide ample opportunity to clarify these ambiguities and thus to accommodate the needs of both the investors and the developing nations. If this issue is examined from a common‐sense perspective, it should not continue to be a stumbling block that would prevent the United States from ratifying this important Convention.