Zur Physiologie der organischen Säuren in grünen Pflanzen

Ohne ZusammenfassungMit 7 Textabbildungen.     

Zur Physiologie der organischen Säuren in grünen Pflanzen. III. Rheum hybridum Hort. (Vorläufige Mitteilung)

Ohne Zusammenfassung     

Widespread fluorescence in terrestrial and marine samples investigated from India

The discovery of green fluorescent protein (GFP) from jellyfish Aequorea victoria has provoked numerous studies to unveil the myriads of biomedical applications. Consequently, several studies also revealed the prevalence of fluorescence in different marine and terrestrial organisms. However, since GFP's discovery or the Nobel prize award on GFP, the fluorescence has not been explored so far from India. The current study presents the widespread fluorescent organisms resources available in India for biomedical and toxicological applications. Fluorescence emission from different plant and animal components were examined by direct observations using UV torchlight. Investigation revealed that blue light excited fluorescence in several organisms. For the first time, this study observed GFP like fluorescence in many terretrial and marine organisms of India. Observations are indicating that fluorescent proteins have essential ecological functions that are yet to be determined. The examined plant and animal components were not bioluminescent. In comparison, the potential untouched research areas on fluorescence aspects are detailed. A thorough review of fluorescent organisms reported hitherto is also provided to spread the current knowledge on fluorescence.     

Untersuchungen am Hühnchen. Die Entwicklung des Keims während der ersten beiden Bruttage

Ohne ZusammenfassungDank schulde ich meinem alten LehrerBraus, der mir zu dieser Arbeit den Anstoß gab; Petersen, meinem Chef, dessen Vertrauen mir die Möglichkeit bot, sie weiter zu führen; Vogt, der den Geist der Materialgeschichtserforschung an seiner alten Arbeitsstelle geweckt hatte und die Agarmethode erfand; Goerttler, der sie mir zeigte; cand. med.Apitz, der mir bei den normalen Durchbeobachtungen half;der Gesellschaft zur Förderung der Wissenschaften in Würzburg, die mir das Geld zum Photographieren gab.     

Long-term cultures of neurons from adult frog brain express GABA and glutamate-activated channels

Cells from adult Xenopus laevis brainstem and spinal cord were dissociated with mild enzymatic treatment and grown in long-term cell culture. These cells had specific attachment/substrate and medium/serum requirements. Cells with bipolar and multipolar morphology were positively identified as neurons using immunohistochemistry with monoclonal antibodies to rat and bovine neurofilament proteins which we show here cross-react with similar amphibian proteins. Patch clamp recordings demonstrated that these neurons have populations of ionic channels which are activated by L-glutamate or gamma-aminobutyric acid (GABA). The characteristics of these channels were similar to those previously described for GABA- and glutamate-activated channels in embryonic mammalian neurons isolated in culture. Cell cultures of neurons isolated from adult Xenopus laevis brain may be a useful and simple preparation with which to examine the modulation of neuronal properties by various agents over longer time intervals then has been previously possible.     

The mammary tumor response in triazine-treated female rats: a threshold-mediated interaction with strain and species-specific reproductive senescence.

Triazine herbicides are among the most heavily used agricultural pesticides. Although they possess a very low acute toxicity in animals, a mammary tumor response has been consistently observed in Sprague-Dawley (SD) female rats following chronic oral dosing of atrazine and simazine at and above maximum tolerated doses. However, a substantial collection of detailed research has clearly shown that triazines are not genotoxic or mutagenic, nor do they possess estrogenic agonist activity that might promote mammary tumor growth. Examination of estrous cycling records of atrazine-treated SD rats revealed a premature appearance of persistent estrous episodes, beyond the prevalent occurrence normally seen in untreated, aging SD rats. A significant correlation has been found between early or severe estrous cycle disruption of atrazine-treated rats and the early appearance of mammary tumors. In studies using SD female rats fed atrazine for 6 months, then ovariectomized and administered an estrogen-containing silastic s.c. implant, a deficient luteinizing hormone surge was observed at a 400 parts per million (ppm) dose, but not at 25 or 50 ppm. Because SD rats exhibiting persistent estrus also have a prolonged elevation of estrogen secretion, it is proposed that the triazine-associated mammary tumor response is promoted by the test animal's own estrogen from ovarian follicles that fail to ovulate because gonadotropin surge sufficiency is blocked by the high dose of herbicide. It is further proposed that, because reproductive senescence in SD rats is fundamentally different from menopause in women, the animal response to dosing, as well as the enormous requisite dosing level, establishes a safety margin of very low risk to human health from this mode of action.     

Zoophycos in storm-affected environments: a case study from lower Maastrichtian deposits of the Mateur-Beja area (Northern Tunisia)

Abstract

The lower Maastrichtian deposits of the Mateur-Beja area in northern Tunisia are mainly composed of fine-grained marl and limestone alternations occasionally interbedded by coarse-grained calcarenites and gravel deposits. In the coarse-grained intervals sedimentary structures are indicative of storm-induced high-energy currents in an outer ramp to slope setting and of local reworking by bottom currents in the basin. In deeper environments, fine-grained sediments accumulated mainly while settling from storm-induced suspensions. The lower Maastrichtian deposits contain abundant Zoophycos exhibiting two main morphotypes, skirt-shaped Zoophycos in deposits around storm-wave base and tongue-shaped Zoophycos in somewhat deeper sediments. The types differ in burrow architecture, morphology of lobes, and size of structural elements. These differences are attributed to different behavioral programs modulated by the availability of benthic food that decreased seaward. Storm-affected environments seem to be a prerequisite for these Zoophycos-producers to choose their habitat.