834 resultados para unicellular and colonial Microcystis


Relevância:

40.00% 40.00%

Publicador:

Resumo:

Mode of access: Internet.

Relevância:

40.00% 40.00%

Publicador:

Resumo:

The medical management of those envenomed by snakes, spiders and poisonous fish in Australia featured extensively in the writings 19th century doctors, expeditioners and anthropologists. Against the background of this introduced medical doctrine there already existed an extensive tradition of Aboriginal medical lore; techniques of heat treatment, suction, incision and the application of plant-derived pharmacological substances featured extensively in the management of envenomed victims. The application of a hair-string or grass-string ligature, suctioning of the bite-site and incision were practised in a variety of combinations. Such evolved independently of and pre-dated such practices, which were promoted extensively by immigrant European doctors in the late 19th century. Pacific scientific toxinology began in the 17th century with Don Diego de Prado y Tovar's 1606 account of ciguatera. By the end of the 19th century more than 30 papers and books had defined the natural history of Australian elapid poisoning. The medical management of snakebite in Australia was the focus of great controversy from 1860 to 1900. Dogmatic claims of the supposed antidote efficacy of intravenous ammonia by Professor G.B. Halford, and that of strychnine by Dr. Augustus Mueller, claimed mainstream medical attention. This era of potential iatrogenic disaster and dogma was brought to a conclusion by the objective experiments of Joseph Lauterer and Thomas Lane Bancroft in 1890 in Brisbane; and by those of C.J. Martin (from 1893) and Frank Tidswell (from 1898), both of Sydney. The modern era of Australian toxinology developed as a direct consequence of Calmette's discovery, in Paris in 1894, of immune serum, which was protective against snakebite. We review the key contributors and discoveries of toxinology in colonial Australia.

Relevância:

40.00% 40.00%

Publicador:

Resumo:

Male Nezara viridula produce sex pheromones from many independent single cells, each with a duct that opens onto the ventral abdominal surface. Despite the presence of along duct and an associated end complex (in the form of a cupule and microvillus saccule), the structural organization of the cells that comprise the gland conform to Class 1 epidermal gland cell classification : a single cell surrounds the entire secretory complex. Each cuticular cupule contains a central bed of filaments and opens into a narrow tubular ductule that leads from the base of the cupule through the epidermis to the cuticle to open externally as a pore. The cuticle of the cupule is continuous with that of the ductule and has the appearance of three layers, although the inner (middle) layer may be a gap formed during construction of the complex. In young adult males, just molted, the ultrastructure of the cells and their inclusions indicate that they are not active. The region of the cell that is distal to the abdominal cuticle is reduced and the proximal region, surrounding the duct, is enlarged when compared with sexually mature (3-4 weeks old) adult males. At maturity the pheromone cells are enlarged distally around the cupule, but are reduced to a narrow sleeve proximally, around the ductule. Two characteristic cell profiles are evident, based on the shape of the cupule and the organelle content. Type A shows a broad opening to the cupule, an abundance of mitochondria, and few vesicular bodies. Type B has an elongated, narrow, vase-like opening to the cupule, few mitochondria, and numerous vesicular bodies. Type B cells are smaller and more abundant than Type A. Distribution within the epidermal layer also differs. It is likely that the different types represent cells producing different secretion profiles. However, the secretions retained by the standard fixation protocol within mature cells of both types look similar and appear to collect as crystalline bodies within the lumen. This may represent a common storage mechanism.

Relevância:

40.00% 40.00%

Publicador:

Resumo:

This dissertation analyzes various types of non-canonical texts authorized by women from a wide spectrum of classes and races in the Spanish colonies. The female voice, generally absent from official colonial documents of the sixteenth, seventeenth and eighteen centuries, left a gap in the complex subject of women's history and social participation. Through the study of personal letters, autobiographies, journals, court documents, inquisitorial transcripts, wills and testaments, edicts, orders, proclamations and posters, that voice is recovered. Thus, the Indigenous, Spaniards and African women and their descendants who lived during this period left their written legacy and proof of participation. Beginning with a thorough history of the native woman's interest in writing, this study focuses on how women of all social levels utilized the few means of writing available at their disposal to display a testimonial, critical and sometimes fictional narrative of their surroundings. ^ This investigation concludes that it is necessary to change the traditional image of the passive women of the colonies, subjected to a patriarchal authority and unable to speak or grow on their own. The documents under study, introduced women who were able to self represent themselves as followers of the tradition while at the same time their writings were denying that very same statement. They passed from the private arena to the public one with discourses that confessed their innermost feelings and concerns, challenged the authority of the Inquisitor or the Governor, exposed their sexual freedom and transvestite narratives, successfully developed stratagems that challenged the official ideology of the oppressive religious environment and established their own authority reaching at last the freedom of their souls. ^