Irregular Growth Pattern Research Articles

Continuing variation in successive asexual generations of Pythium splendens following sexual reproduction

Stability of the phenotypic characteristics of growth rate, colony type, sensitivity to streptomycin and sensitivity to chloramphenicol of the conidium progeny of selfed oospore cultures of Pythium splendens was investigated. Progeny were divided into parental A type, D type for those deviated from A type but with uniform pattern and M type for those with irregular growth pattern or with dissimilar appearance on two replicate plates. Conidium progeny of A type isolate 167F and its A type oospore cultures showed the same colony type and displayed little variation in growth rate, and sensitivity to streptomycin and chloramphenicol. The D and M type oospore cultures displayed considerable variation in all phenotypic characteristics measured. Similar variation in conidium progeny following selfing was observed in isolate 167F-9, an A type oospore progeny of isolate 167F. Following sexual reproduction conidium progeny continued to vary in second and third conidium generations tested. The phenomenon of continuing variation in successive asexual generations induced by sexual reproduction may plan an important role in evolution, survival and development of pathogenicity and fungicide resistance of an organism by increasing the diversity and extent of the constitutive variation resulting from gene recombination during sexual reproduction.

Sagittal otolith growth patterns in regularly and irregularly spawning burbot,Lota lota, in northern Finland

Sagittal otolith growth patterns were compared among three burbot,Lota lota, populations in northern Finland. Coastal burbot off Simo on the northern coast of the Bothnian Bay and lake burbot from Lake Kemijarvi represented populations with about 30% non-spawning adult individuals, while the river burbot from the River Kitinen spawned regularly. Irregular growth patterns i.e. crenulations on the dorsal edge of the sagitta and pointed extensions in the rostrum region and cloudy appearance of the sagittal otoliths, as observed by light, scanning and transmission microscopy, occurred significantly more often in the coastal and lake burbot than in the river burbot. This could not be explained by differences in age or size. Its possible relationship to supposed reproduction disorder is discussed.

Regeneration capacity and productivity of natural forest in Burkina Faso

In 1983 trials were established at four sites in Burkina Faso to study, through annual inventories, the potential regeneration capacity and productivity of natural forest in a coppice exploitation. The trials, planned for a period of 20 years, are in the Sudano-Sahelian zone (Yabo), North-Sudanian zone (Bissiga and Sâ) and South-Sudanian zone (Toumousséni). After 5 years, good regeneration was found at all sites. The original felled population showed a mortality varying from 11.1% (Sâ) to 17.6% (Yabo), and the average dominant height varied from 2.12 m (Yabo) to 3.07 m (Sâ). The strong initial increase of the dominant height fell back sharply after 2 years for Yabo and Bissiga and after 3 years for Sâ. Toumousséni showed poor initial height growth but good growth for the following 3 years. In 1988 the trials were partially felled to establish volume equations. Estimated average productivity over a period of 5 years in m 3 ha −1 year −1 was 0.61 (Yabo), 0.80 (Bissiga), 1.04 (Sâ) and 0.93 (Toumousséni). It is provisionally expected that the maximum average productivity will be reached in the seventh or eighth year for Yabo and Bissiga, and a few years after that for Sâ. The regeneration at Toumousséni sustained a major setback during the first years due to dense grass development after the felling, but it has recovered well and its average productivity will soon surpass that at Sâ. As a separate part of the trial a number of plots were felled on four different dates, of which three were felled after the first rainy season of the main trial had passed. It was found that these younger plots showed, for two investigated years, the same irregular height growth pattern as the older plots. A relation with rainfall figures was not found.

Fibro-osseous pseudotumor of the digits.

Twenty-one cases of a benign fibro-osseous pseudotumor occurring in the soft tissues of the digits are described. They affected mostly young adults. Twenty of the 21 cases involved the soft tissues of the fingers, especially the proximal portions of the index or middle finger, and one case involved the toe. Microscopically these tumor-like lesions closely resembled myositis ossificans, but unlike this process they involved chiefly the subcutaneous tissue and adjacent fibrous structures and were marked by an irregular multinodular growth pattern without the typical zoning of myositis ossificans. Because of the focal hypercellularity, cellular atypia and increased mitotic activity six of the cases were initially interpreted as being parosteal or extraskeletal osteosarcoma. Follow-up information indicates that this lesion behaves in a nonaggressive fashion and is curable by complete local excision.

Cytokinin autotrophy and differentiation in tissue cultures of haploid Nicotiana tabacum L.

Explants from the apical region (10 cm from the tip) of haploid Nicotiana tabacum cv. Wisconsin-38 were cultured on media with and without kinetin. Cell lines were selected in the dark and in the light. Cytokinins were extracted from the apical region of haploid plants and from callus tissues after 84 days of growth (third transfer culture). Chlorophyll was extracted from callus grown under light after 21 days of growth at each of the four cell line selection steps. Kinetin (+) cell lines and cytokinin autotrophic tissues grown in the light showed a compact growth pattern. Microscopic examination of these callus showed the presence of large numbers of nodules consisting of tracheary elements, parenchymatic cells, sieve elements and meristematic cells. Cytokinin-autotrophic callus grown in the dark showed an irregular growth pattern presenting regions of compact tissue and friable tissue. The compact tissue contained large amounts of nodules similar to those of kinetin (+) tissues and of cytokinin autotrophic tissues grown in the light. Extraction of the compact and the friable callus components showed high cytokinin activity in the compact region and low activity in the friable portion. It is suggested that cytokinin synthesis is related to the differentiation of the nodular structures. The amount of chlorophyll increased during the process of cytokinin autotrophic cell line selection.

Tumour volume and macroscopic growth pattern of bronchogenic carcinoma.

126 resected malignant lung tumours were cut into serial sections. The tumour volume, the pTN-stage and the macroscopic growth pattern were computed. The average tumour volume was found to be 28.5-35.8 cm3 (confidence limits, p greater than or equal to 95%) and to be independent of the major cell type of the carcinomas. The cell types grow in different macroscopically distinguishable tumour growth patterns: epidermoid carcinomas grow mostly in bizarre finger-like shapes and small cell anaplastic and adenocarcinomas more frequently in ball-like shapes. The different growth patterns depend on the cell type, the cellular response of the host tissue and the tumour volume. Due to irregular growth pattern the tumour volume computed by X-ray diameter is likely to be overestimated by 50%-300%.

La Condition urbaine vue sous l’angle de la conjoncture économique : Sherbrooke, 1875 à 1914

The cycles of depression and expansion in the history of capitalist countries can also be studied at the level of the industrial city. Sherbrooke's tax rolls — which are as accurate as any annual municipal census — make it possible to trace the irregular growth pattern of a burgeoning city. This article looks at how employment, housing, material and social living conditions and tendencies toward residential permanency or transience changed from 1875 to 1913 with the unequal and combined movement of long-term trends and short economic cycles. The study of eleven neighbourhoods makes it possible to identify different growth development rhythms in relation to ethnic or socio-professional traits and by residential sector.

A diploid rat liver cell culture. IV. Malignant transformation by aflatoxin B1.

Chronic exposure of a cloned rat hepatocyte culture (RL-PR-C) to a subtoxic, sublethal dose of aflatoxin B1 resulted in malignant transformation. Continuous exposure to aflatoxin B1 caused increasing tumorigenic potential as tested by back injection into isogenic animals. Control cultures exhibited spontaneous transformation, although approximately 20 passages beyond the chemically induced event. Neither aflatoxin-treated nor control cultures exhibited cytopathological morphology, formation of cell foci, growth in soft agar, or irregular fibroblast-like growth patterns that could be specifically related to the onset of tumorigenic potential. In general, those parameters commonly used to monitor fibroblast cultures for transformation in vitro were not applicable for assessing the tumorigenic potential of these epithelial cells. Karyotypic analyses revealed no specific chromosomal aberrations associated with aflatoxin treatment; however, chromosomal instability was a property of the tumorigenic cell populations. Injection of both aflatoxin-treated and control cultures at passage 56 resulted in tumors indicative of both carcinoma and sarcoma indicating to us the multipotency of these epithelial cells transformed in vitro.

Scanning electron‐microscopic study of the surface characteristics of neoplastic endo‐thelial cells of blood vessels

The morphological surface characteristics of neoplastic endothelial cells of blood vessels induced by oral administration of 1,2-dimethylhydrazine dihydrochloride in mice were studied by scanning electron microscopy. The interconnecting vascular channels were lined by malignant endothelial cells which formed bridges, cord-like structures and had extended cytoplasmic processes which made the network more intricate. The endothelial cells were often in close approximation to each other and exhibited irregular growth patterns and orientation. The cell surface displayed a rugged, terrace-like microcontour of elevations, depressions, blebs and nodular structures. These findings correlate with the earlier morphological observation obtained by transmission electron microscopy.

A SCANNING ELECTRON MICROSCOPE STUDY OF OLIVINE CRYSTAL SURFACES

SEM photographs were taken of euhedral olivine grains from the Murchison C2 chondrite and several terrestrial and lunar occurrences. In general, the crystal faces of the meteorite grains are rough and uneven, with irregular growth patterns. They are very similar to crystal faces on terrestrial olivine grains that formed by sublimation from a vapor phase. They are very different from the relatively smooth and featureless surfaces of magmatic olivine crystals that precipitated from igneous melts. Qualitatively, the surface morphology of the crystal supports the contention that many euhedral crystals of olivine in C2 meteorites condensed from a gas phase.

Genetic Evidence for Hybridization in an Interspecific Cross in the Genus Sordaria

SUMMARY: When the two heterothallic species Sordaria heterothallis and S. thermophila are crossed, two types of viable ascospores are recovered. The first, the mature black ascospore, is produced with a mature eight-spored ascus formed from an intraspecific fusion of nuclei of the same mating type. The second, the non-pigmented germinable ascospore, is produced by the interspecific fusion of nuclei of opposite mating types within an ascus in which all other ascospores are aborted. The non-pigmented ascospore is the product of the mixed genomes of the two species. It is a recombinant spore from which either species may be obtained by the partial substitution of its genome through successive backcrosses. Its inability to develop pigmentation, the irregular growth patterns of some of the strains which it produces and their inability to react in complementation tests, appear to be the result of a lack of affinity between the two species.