The biological half-life of bromine in the rat thyroid was determined by measuring the radioactivity of thyroids of animals which continuously received 82Br labelled bromide in their food. The value of this half-life (110 h) is practically the same as the biological half-life of iodine. The rate of establishing the I/Br concentration ratio in the thyroid depends on the biological half-life of bromine. The mechanism of this process depends on the state of iodine supply. When the supply is sufficient, the iodine concentration in the thyroid remains constant, while during iodine deficiency the iodine atoms are replaced by atoms of bromine.
Duponchelia fovealis Zeller is a polyphagous insect that has been recently reported attacking strawberry plants (Fragaria x ananassa Duchesne). Despite its economic importance there are few studies on this pest because it is difficult to rear it in the laboratory. With a constant supply of insects, studies on alternative methods of pest control can be conducted. This study aimed at developing an artificial diet for rearing D. fovealis with biological characteristics similar to those reared on their natural diet. This study was carried out in a climate-controlled room (25°C ± 2°C, RH 70% ± 10%, and 14L : 10D). The natural diet consisted of 'San Andreas' strawberry leaves (D1), while the artificial diet (D2) was developed in which beans, casein, soy protein, yeast and wheat germ are used as sources of protein. Five instars were identified. D. fovealis completed its life cycle in 38 and 40 days when fed D1 and D2, respectively. Survival was highest for the larvae fed the artificial diet. Females fed D1 lay a mean of 300.2 ± 62.3 eggs, while those fed D2, 220.3 ± 41.8 eggs. The artificial diet is suitable for the continuous rearing of D. fovealis in the laboratory., Maria A. C. Zawadneak, Rodrimar B. Gonçalves, Alex S. Poltronieri, Bráulio Santos, Adélia M. Bischoff, Aline M. Borba, Ida C. Pimentel., and Obsahuje bibliografii
The biological soil crusts (BSCs) in the NW Negev cause local water redistribution by increasing surface runoff. The effects of pore clogging and swelling of organic and inorganic crust components were intensively investigated in earlier studies. However, the effect of water repellency (WR) was not addressed systematically yet. This study investigates subcritical WR of BSCs in three different study sites in the NW Negev. For this purpose, three common methods to determine soil WR were used: (i) the repellency index (RI) method (ii) the water drop penetration time (WDPT) test and (iii) the Wilhelmy plate method (WPM). Furthermore, the potential influence of WR on local water redistribution is discussed and the applied methods are compared. We found the BSC to be subcritically water repellent. The degree of WR may only affect water redistribution on a microscale and has little influence on the ecosystem as a whole. The RI method was clearly the most appropriate to use, whereas the WDPT and the WPM failed to detect subcritical WR.
Stále se rozšiřující aplikace SPM přístrojů přinesly možnost zobrazovat bez větších problémů vzorky přímo v kapalných prostředích. To umožňuje zobrazit povrch vzorku s minimální silou mezi hrotem a povrchem a vyhnout se tak například poškození povrchu biologického preparátu. Režimy AFM používané v kapalném prostředí pro biologické vzorky jsou prakticky totožné s klasickými analýzami AFM. Ve větší míře se však využívá poklepový režim. Článek předkládá přehled typických aplikací AFM se skenerem pro kapalná prostředí (liquid scanner)., Roman Kubínek, Milan Vůjtek, Renata Holubová, Zdeňka Zapletalová, Hana Kolářová., and Obsahuje seznam literatury
Severoameričtí raci (např. rak pruhovaný a rak signální vyskytující se i v ČR) jsou příkladem invazních živočichů, jejichž invazní potenciál je zesílen přenosem onemocnění nebezpečného pro příbuzné druhy z jiných geografických oblastí. Původcem nemoci, tzv. račího moru, je Aphanomyces astaci ze skupiny Oomycetes způsobující úhyny celých populací evropských raků. Račí mor se v Evropě vyskytuje už od 19. století a i v současnosti zůstává přes intenzívní výzkum jedním z nejvýznamnějších faktorů ohrožujících původní raky (u nás jde o raka říčního a raka kamenáče, u nichž bylo jen od roku 2004 zaznamenáno deset případů zdecimování populací touto nemocí)., North American crayfish species such as the Spiny-cheek Crayfish and the Signal Crayfish are examples of invasive animals with an ability to carry and transmit a disease lethal to their relatives from other parts of the world. The disease called the crayfish plague and caused by Aphanomyces astaci (Oomycetes) may eradicate whole populations of the indigenous European crayfish. The disease is known in Europe from the 19th century and despite intensive research it is still one of the main factors endangering indigenous crayfish., and Eva Kozubíková-Balcarová.