Showing papers by "University of Siena published in 1974"
TL;DR: Although incompatible tubes very much resemble, in this respect, the pollen tubes cultured in vitro, it seems probable, on theoretical grounds, that the inhibition of pollen tubes in incompatible styles does not result from an absence of growth promoting substances but from the presence of a metabolic inhibitor.
Abstract: Cytological and genetical analyses were made of the breeding system of embryo-cultured interspecific tomato hybrids between L. esculentum and L. peruvianum. It was found that fluorescence techniques and electron microscopy allowed a distinction to be made between pollen tubes inhibited by a unilateral incompatibility reaction and pollen tubes inhibited by a self-incompatibility reaction, after self-pollination of the hybrids or after reciprocal crossing between the hybrid and the parental species. The observed differences, if real and reliable, demonstrate that unilateral incompatibility in esculentum pollen tubes is governed by a single gametophytic factor which is either linked or allelic to the S-locus. This finding is discussed with reference to recent reports that unilateral incompatibility is controlled, in peruvianum styles, by a number of different dominant genes and it is concluded that these dominant genes, the S-locus of self-incompatibility and the gametophytic factor regulating the unilateral reaction in esculentum pollen belong to the same linkage group. The strong sterility barriers which prevent practically all backcrosses between the hybrid and the parental species were shown to be independent of the factors regulating stylar incompatibility. L. peruvianum is heterozygous for the sterility genes which prevent fertilization or embryo formation when the interspecific hybrid is crossed, as pistillate parent, to different accessions of L. peruvianum. One peruvianum stock was found which, as a pollinator, was highly cross-fertile with the hybrids.
73 citations
TL;DR: In rabbits on a hypercholesterolic diet, the surface of the plaques, at scanning electron microscope examination, looks discontinuous even in specimens obtained with the “critical point” device.
Abstract: In rabbits on a hypercholesterolic diet, the surface of the plaques, at scanning electron microscope examination, looks discontinuous even in specimens obtained with the “critical point” device. Discontinuities of the endothelial lining of the plaques are found also in ultrathin sections by transmission electron microscopy: foam cells do then constitute the superficial row. In proliferative lesions, smooth muscle cells are actively surfacing, reaching sometimes the lumen.
37 citations
TL;DR: The authors describe a new model of sperm axoneme, the “9 + 9 + 3,” which is characteristic of simuliid Diptera, which has a row of very long side projections rich in ATPase activity, but the flagellum lacks the central sheath.
32 citations
TL;DR: Tubular paracrystalline structures have been found in the cytoplasm of the inner integument of Diplotaxis erucoides and it may be suggested that the structures present in the integument are gradually utilized for the development of the embryo.
28 citations
TL;DR: The morphological data seem to indicate that absorption and transport of nutrients from the surrounding tissues is a main function of Diplotaxis erucoides and that the suspensor starts to degenerate disintegrating shortly after the torpedo stage of the embryo.
Abstract: The development and general morphology of Diplotaxis erucoides (L.) DC. suspensor is of the « Onagrad Type », « Alyssum Variation ». Maximum growth of the suspensor occurs from the globular to the early heart stage of embryo development. The suspensor starts then to degenerate disintegrating shortly after the torpedo stage of the embryo. The wall ingrowths of the long, tapering, basal cell are especially abundant at the cell's micropilar pole which is closely surrounded by well developed wall ingrowths formed by the endosperm. Wall ingrowths and plasmodesmata are present on the suspensor cells cross walls with the exception of the cell closest to the embryo. No such structures in fact are present on the walls separating this last cell both from the embryo and from the rest of the suspensor. Wall ingrowths are generally associated with numerous, large, mitochondria. The morphological data seem to indicate that absorption and transport of nutrients from the surrounding tissues is a main function of...
22 citations
TL;DR: The results indicated that previously reported increases in liver xanthine oxidase levels in patients with gout, who were overexcretors, were neither primary nor genetically determined but were related to increased production of the enzyme.
Abstract: The behavior of xanthine oxidase in the jejunal mucosa of patients with gout and in the liver of normal subjects during secondary drug-induced hyperuricemia was studied. Xanthine oxidase activity was not increased significantly in the jejunal mucosa of patients with gout, whereas an RNA, hypoxanthine, EA-TDA, or fructose load in normal subjects caused liver xanthine oxidase levels to rise to values that were two- to fourfold higher than those for the control group. The results indicated that previously reported increases in liver xanthine oxidase levels in patients with gout, who were overexcretors, were neither primary nor genetically determined but were related to increased production of the enzyme.
20 citations
TL;DR: The authors describe the spermiogenesis of Polyxenus lagurus, a diplopod, in the male genital ducts and the transformations the spermatozoon successively undergoes in the Spermatheca.
Abstract: The authors describe the spermiogenesis of Polyxenus lagurus, a diplopod, in the male genital ducts and the transformations the spermatozoon successively undergoes in the spermatheca.
The spermatozoon in the male genital ducts looks like a little barrel devoid of centriole and of any kind of rudimentary flagellum whatever. The organelles are markedly modified; cross sections present an elongated, flattened nucleus, an X-shaped body running parallel to it on the opposite side and two longitudinal mitochondrial strips interposed between them. The rest of this barrel-shaped spermatozoon is filled with peculiar Golgi formations, the spongy chambers, which open outwards through little vents.
In the spermatheca the spermatozoon is quite different: it is shaped like a long ribbon. The basic structure of the spermatozoon is formed by the double folding of part of the cortical layer of the barrel-shaped spermatozoon. On the central part of this endo-skeleton are longitudinally ranged the nucleus and the acrosome flanked on both sides by a thread of mitochondria. Even in this phase the sperm has no flagellum.
18 citations
TL;DR: The spermatozoon of M. buxi which belongs to the Cecidomyiidae family has been studied and is characterized by the lack of acrosome, and by the presence of normal mitochondria apically gathered before the nucleus.
Abstract: The spermatozoon of M. buxi which belongs to the Cecidomyiidae family have been studied. The spermatozoa have an aberrant flagellum somewhat similar to that of Sciaridae formed by about 170 doublets ranged in rows to form a compact bundle. Accessory tubules and all the other axonemal structures are missing. The sperm is characterized by the lack of acrosome, and by the presence of normal mitochondria apically gathered before the nucleus.
14 citations
01 Jan 1974
10 citations
7 citations
TL;DR: In this paper, a carattere espositivo alle strutture algebriche legate con le teorie che esprimono Theor and nelle quali vale the lemma di diagonalizzazione.
Abstract: Si da un'introduzione a carattere espositivo alle strutture algebriche legate con le teorie che esprimono Theor e nelle quali vale il lemma di diagonalizzazione. In 1. 2. 3. sono richiamate alcune proprieta basilari dell'aritmetica peaniana e nei numeri succssivi vengono introdotte le suddette strutture e presentati alcuni problemi aperti.
01 Jan 1974
01 Jan 1974
TL;DR: In this paper, the results of laboratory experiments carried out on clay samples in the ranges 1 · 10−2 − 5 · 103 Hz and 20° − 100°C were given.
TL;DR: In this paper, an account is given of the possibility of modifying the two-layer magnetotelluric master curves by considering both electrical frequency dispersion and temperature, and an account of the possible modifications is given.
TL;DR: The formation of polygranular aggregates is probably caused by the fact that not all the leaf starch of a full-grown plant of Smilax aspera is strictly “transitory” starch.
01 Jan 1974
TL;DR: The morphological differences constantly present between the fibroblastoid cells and the spindle-shaped ones, as well as their different behaviour when stained with fluorochromes, support the view that these cells are two different entities.
Abstract: Thein-vitro culture of pathological tissue of Kaposi's disease has induced the growth of three cell types: epithelioid cells, apparently not significant, which proliferated from the epithelial component; branched fibroblastoid cells with a large nucleus; and bipolar spindle-shaped cells with a smaller nucleus. The morphological differences constantly present between the fibroblastoid cells and the spindle-shaped ones, as well as their different behaviour when stained with fluorochromes, support the view that these cells are two different entities. Numerical and structural chromosomal modifications were not found in the cultured cells.
TL;DR: In this paper, an attempt is made to appraise the overall significance of the Rome Conference and the possibilities and limitations of what appear to be its main conclusions, in view of the wide coverage by the press of the work of the Conference, it is assumed that the topics discussed in Rome and the large number of resolutions adopted are by now sufficiently known.
Abstract: Summary The scope of this note is twofold. Firstly, an attempt is made to appraise the overall significance of the Rome Conference and the possibilities and limitations of what appear to be its main conclusions. In so doing, and in view of the wide coverage by the press of the work of the Conference, it is assumed that the topics discussed in Rome and the large number of resolutions adopted are by now sufficiently known. For further information the reader is referred to the Conference report.1 Secondly, some of the issues raised and lines of action proposed in the article by A. Simantov (this issue) will be briefly reviewed in the light of the information made available by the Rome Conference. This approach seems justified, among other reasons, by the consideration that Simantov's article was written some time before the Conference.
Journal Article•
TL;DR: In this article, the oxidation of α-tocopherol in conc. solutions of acetic acid by vanadium(V) has been utilized for its quantitative determination, and two procedures were developed.
Abstract: The oxidation of α-tocopherol in conc. solutions of acetic acid by vanadium(V) has been utilized for its quantitative determination. Two procedures were developed. In the first one α-tocopherol is titrated with a standard vanadium(V) solution applying either potentiometric or biamperometric indicating system. Amounts of 2–20 mg were determined with a relative standard deviation of 0.3–2.8% and a relative error of 1.5%; the titration is feasible also in ethanol-H2SO4 solution. In the second method vanadium(V) is electrogenerated from 0.1 M VOSO4 solution in acetic acid and a modified amperometric procedure for end-point detection is employed. Amounts of 0.1–2 mg of α-tocopherol were titrated with a relative standard deviation of 0.7–4.3% and a relative error of 2.5%.
TL;DR: Environmental conditions in the sea inlet are optimal for Crassostrea angulata and therefore that it would be a suitable place to develop the culture of oysters, before the complete disruption of the bottom by the undisciplined local fishermen takes place.