Conversion of cellulose into fungal cell mass in solid state culture

Summary To satisfy the demand for simple production technology (simple and cheap reactor, cheap recovery and finishing), solid state cultivations were carried out with pretreated straw in a simple fixed bed reactor under nonsterile conditions.The results of these investigations were compared with those evaluated in a stirred tank reactor. The same cell mass fractions were obtained in both reactors. However, about double the cultivation time is necessary for a solid state cultivation as compared to a submerse cultivation.Symbols N₂ nitrogen content of dry biomass (%) - P productivity on cell protein (%/h) - T temperature (°C) - t_F cultivation time (h) - X fungal cell mass fraction (%)     

A rapid naphthol yellows method for measuring the cellular protein content of anchorage cultures

Summary A rapid method has been developed for measuring the cellular protein content of mono- and multilayered anchorage cultures. Fixed or air dried cultures are stained for 30 min with 0.2% Naphthol Yellow S (NYS) dissolved in 1% acetic acid. Unbound dye is removed by a series of four 2.5 min washes in 1% acetic acid, and protein-bound dye extracted with 10 mM unbuffered Tris base for spectrophotometric optical density determination at 433 nm. The NYS method exhibited a least-squares correlation coefficient of 0.99997 with the Oyama-Eagle Lowry method.     

DNA probe localization at 18p113 band by in situ hybridization and identification of a small supernumerary chromosome

Summary Recombinant plasmid clone B74 (also named D18S3) containing a human single-copy DNA segment of 6 kilobases (kb) was localized by in situ hybridization on band p113 of chromosome 18. This probe was then used in cytogenetic diagnosis to identify precisely a small supernumerary chromosome as an isochromosome i(18p).     

Nonvisual feeding in a visual planktivore,Xenomelaniris venezuelae

Summary Studies of the diel feeding patterns of the planktivorous fish, Xenomelaniris venezuelae, in Lake Valencia, Venezuela, revealed that, although the fish is primarily a diurnal feeder, it consumes substantial numbers of Chaoborus larvae and pupae at night. A number of fish species are known which feed on plankton at night, but these fish are filter feeders and their diets largely consist of relatively small, nonevasive prey. Chaoborus, however, is large and agile. Predation by Xenomelaniris in the dark was also studied experimentally. Captured fish were placed in completely darkened aquaria with zooplankton from Lake Valencia. After several hours the plankton was removed and examined for evidence of feeding. The fish were found to consume Chaoborus pupae and fourth instar larvae but not other types of prey. The mode of feeding by Xenomelaniris in the dark is unknown.     

The daily timing of lamprey attacks

Synopsis Laboratory and field data suggest that several species of parasitic lampreys forage primarily at night, but data forPetromyzon marinus are equivocal. Nocturnal foraging may minimize predation risk. This may be particularly important to those species of lampreys that inhabit shallow streams. Nocturnal foraging also may enhance foraging efficiency if potential hosts at night are quiescent and more easily approached. Future experiments should be designed to avoid several potential sources of bias.     

Partial purification,subunit structure and thermal stability of the photochemical reaction center of the thermophilic green bacterium Chloroflexus aurantiacus

Spectrally pure reaction center preparations from Chloroflexus aurantiacus have been obtained in a stable form; however, the product contained several contaminating polypeptides. The reaction center pigment molecules (probably three bacteriochlorophyll a and three bacteriopheophytin a molecules) are associated with two polypeptides (M_r = 30000 and 28000) in a reaction center complex of M_r = 52000. No carotenoid is present in the complex. These data together with previous spectral data suggest that the Chloroflexus reaction center represents a more primitive evolutionary form of the purple bacterial reaction center, and that it has little if any relationship to the green bacterial component. A reaction center preparation from Rhodopseudomonas sphaeroides R26 was fully denatured at 50°C while the Chloroflexus reaction center required higher temperatures (70–75°C) for complete denaturation. Thus, an intrinsic membrane protein of a photosynthetic thermophile has been demonstrated to have greater thermal stability than the equivalent component of a mesophile.     

Studies of the mobility of maleimide spin labels within the erythrocyte membrane

We have confirmed a method yielding reproducible and reliable spectrometric parameters derived from spin-labeled erythrocyte ghosts using nitroxide derivatives of maleimide compounds. The disorder parameter, W/S, was shown to vary with changes in the structure of the label, the conditions utilized for labeling such as ionic strength and erythrocyte age and the presence of drugs such as alcohol and acetaminophen. The nitroxide spectrum was also found to change with increasing and decreasing temperature in an irreversible manner. These findings should permit increased reliance to be placed on the spin-labeling technique when used to monitor changes in membrane lipid or protein assembly.     

Effect of oxygen removal on hydrogen photoproduction in algae

Hydrogen photoproduction from water in Scenedesmus cells requires removal of oxygen by a reagent in contact with the algae. Both deoxyhemoglobin and deoxymyoglobin stimulated hydrogen production by reversible absorption of oxygen. Their effectiveness was greatly increased when other oxygen-combining reagents were present in a separate chamber with deoxyhemoglobin and deoxymyoglobin serving as reversible oxygen transfer agents.