Elektronenmikroskopische Untersuchungen an Streptomyces purpurascens Lindenbein

Zusammenfassung Zellmaterial des Rhodomycinbildners Streptomyces purpurascens Lindenbein, Stamm P 2a, wurde nach verschiedenartiger und unterschiedlich langer Vorkultur unter Anwendung mehrerer Fixierungs-methoden in Form von Ultradünnschnittpräparaten elektronenmikroskopisch untesucht.Es wurden 2 unterschiedliche Zelltypen beobachtet: Zellen, die nur ein fein granuliertes graues Plasma zu enthalten schienen und - aus dem Stadium der Rhodomycinbildung stammende — Zellen mit einer Reihe scharf umrissener Innenstrukturen.Die beobachteten Zellelemente werden beschrieben und bildlich dargestellt. Ihre Dimensionen werden bestimmt.Das Ergebnis der Arbeit wird an Hand der einschlägigen Literatur diskutiert.Zusatz bei der Korrektur. Soeben erschien die Arbeit von D. C. Stuart, jr.: J. Bact. 78, 272, August 1959, in der grundsätzlich bei Streptomyces noursei ähnliche Ergebnisse erzielt wurden. In einer späteren Arbeit wird hierauf zurückzukommen sein.     

Cryoprotection of red blood cells by 1,3-butanediol and 2,3-butanediol

1,3-Butanediol and 2,3-butanediol have been used in buffered solutions with 20, 30, or 35% (w/w) alcohol to cool erythrocytes to -196 degrees C at different cooling rates between 1 to 3500 degrees C/min, followed by slow or rapid rewarming. 1,3-butanediol shows the same shapes of red blood cell survival curves as 1,2-propanediol. Having nearly the same physical properties, they have comparable effects on cell survival. The classical maximum of survival for intermediate cooling rates and an increase for the highest cooling rates are observed. This increase seems to be correlated with the glass-forming tendency of the solution. After the fastest cooling rates, a warming rate of 5000 degrees C/min is sufficient to avoid cell damage, but a warming rate of 100-200 degrees C/min is not. Yet both of these rates would be insufficient to avoid the intracellular ice crystallization on warming. The damage on warming after fast cooling seems once again to be correlated with the transition from cubic to hexagonal ice. For all our results, 1,3-butanediol is like a "second" 1,2-propanediol and could be useful as a cryoprotectant for preservation by total vitrification. 2,3-Butanediol always gives extremely low survival rates, though it presents good physical properties. The crystallization of its hydrate seems to be lethal on cooling or on rewarming.     

Picoplankton culture assessment using single strand conformation polymorphism and partial 18S sequencing

Environmental water samples were taken throughout 2001 fromfractioned water samples at the Helgoland time series site.The less than 3-µm fraction was inoculated into variousmedia. Serial dilutions from these inoculations produced a largenumber of rough cultures from which several hundred well-growingpicoplankton cultures were started. We established a combinationof crude DNA extraction, single strand conformation polymorphism(SSCP) fingerprinting and subsequent sequence analysis to screenthese large numbers of cultures, assess their purity/clonalityand determine their identity. Picoplankton species (i.e., cellssmaller than 3 µm) are difficult to distinguish becauseof their small size and the lack of morphological characters.Therefore, molecular techniques provide the most reliable methodto achieve their identification. Cultures were enriched forphotoautotroph cells, i.e., no carbon source was added, andcultures were grown in the light. From these cultures, crudeDNA was extracted, which was used for partial 18S polymerasechain reaction (PCR). On average, 50% of the cultures produceda PCR product. SSCP analysis of PCR products revealed the clonalityof a given culture. If clonal, then there was only a singleSSCP band; if not clonal, then there were multiple SSCP bands.Single SSCP bands were subsequently sequenced, and sequenceswere used to identify the culture. For this study, 300 cultureswere screened resulting in the identification of 63 potentiallyclonal cultures. These methods proved to be relatively easyto apply to assess the clonality and purity of the cultures.     

No enhanced recognition memory,but better source memory for faces of cheaters

Previous studies sought to test for the existence of a “cheater-detection module” by testing for enhanced memory for the faces of cheaters, but past results have been inconclusive. Here, we present four experiments showing that old–new discrimination was not affected by whether a face was associated with a history of cheating, trustworthy or irrelevant behavior. In contrast, source memory for faces associated with a history of cheating (i.e., memory for the cheating context in which the face was encountered) was consistently better than source memory for other types of faces. This pattern held under a variety of conditions, including different types of judgments participants made about the stimulus persons (attractiveness in Experiment 1; likeability in Experiments 2–4), different retention intervals (a few minutes in Experiments 1, 2 and 4; 1 week in Experiment 3), whether the behaviors were exceptional or ordinary (Experiments 1–3) and whether the social status of the characters was low or high (Experiment 4). Given no differences in old–new discrimination, enhanced source memory for faces of cheaters may be useful for avoiding cheaters in future interactions.     

Zur Isolierung von Luftkeimen mittels feinporiger Filter

Ohne Zusammenfassung     

Decreased intestinal polyp multiplicity is related to exercise mode and gender in ApcMin/+ mice.

Moderate-intensity treadmill running can alter male Apc(Min/+) mouse polyp formation. This purpose of this study was to examine whether exercise mode differentially affects Apc(Min/+) mouse intestinal polyp development in male and female mice. Male and female Apc(Min/+) mice were randomly assigned to control, treadmill (18 m/min; 60 min/day; 6 days/wk), or voluntary wheel running (24-h access) groups. Nine weeks of training decreased total intestinal polyps by 29% in male treadmill runners (66 +/- 9; P = 0.038) compared with male controls (93 +/- 7). The number of large polyps (>/=1-mm diameter) were also reduced by 38% in male treadmill runners (49 +/- 6; P = 0.005) compared with male controls (79 +/- 6). Treadmill running in female Apc(Min/+) mice and wheel running in both genders did not affect polyp number or size. Spleen weight decreased in male treadmill runners (91 +/- 9 mg; P = 0.011) and wheel runners (75 +/- 6 mg; P = 0.004) compared with controls (141 +/- 13 mg). Plasma IL-6 was reduced by 96% in male treadmill runners (1.2 +/- 0.6 pg/ml) and 78% in male wheel runners (6.6 +/- 3.3 pg/ml) compared with control mice (27.9 +/- 2.8 pg/ml; P < 0.05). Female mice responded similarly with an 86% decrease in plasma IL-6 with treadmill running (3.2 +/- 1.2 pg/ml) and 90% decrease with wheel running (2.9 +/- 2.0 pg/ml) compared with control mice (21.1 +/- 5.3 pg/ml; P < 0.05). The crypt depth-to-villus height ratio in the intestine, an indirect marker of intestinal inflammation, decreased by 21 (P = 0.024) and 24% (P = 0.029), respectively, in male and female treadmill runners but not wheel runners. Physical activity-induced attenuation of intestinal polyp number and size is dependent on exercise mode and differs between genders. The modulation of systemic and intestinal inflammation may also depend on exercise mode.     

Key transitions in morphological development improve age estimates in white sturgeon Acipenser transmontanus

We reared white sturgeon Acipenser transmontanus under laboratory conditions and found that a random-forest model containing scute counts and total length predicted age significantly better than total length alone. Scute counts are rapid, inexpensive and non-lethal meristics to gather in the field. This technique could improve age estimates of imperilled sturgeon populations.     

The role of hydrogen bond acceptor groups in the interaction of substrates with Pdr5p, a major yeast drug transporter

The yeast ABC (ATP-binding cassette protein) multidrug transporter Pdr5p transports a broad spectrum of xenobiotic compounds, including antifungal and antitumor agents. Previously, we demonstrated that substrate size is an important factor in substrate-transporter interaction and that Pdr5p has at least three substrate-binding sites. In this study, we use a combination of whole cell transport assays and photoaffinity labeling of Pdr5p with [(125)I]iodoarylazidoprazosin in purified plasma membrane vesicles to study the behavior of two series of novel substrates: trityl (triphenylmethyl) and carbazole derivatives. The results indicate that site 2, defined initially by tritylimidazole efflux, requires at least a single hydrogen bond acceptor group (electron pair donor). In contrast, complete inhibition of rhodamine 6G efflux and [(125)I]iodoarylazidoprazosin binding at site 1 requires substrates with three electronegative groups. Carbazole and trityl substrates with two groups show saturating, incomplete inhibition at this site. This type of inhibition is frequently observed in bacterial multidrug-binding proteins that use a pocket with multiple binding sites. The presence of multiple sites with different requirements for substrate-Pdr5p interaction may explain the broad specificity of xenobiotic compounds transported by this protein.