Protoplast formation and regeneration in <Emphasis Type="Italic">Lactobacillus delbrueckii</Emphasis>

Method for production and regeneration of Lactobacillus delbrueckii protoplasts are described. The protoplasts were obtained by treatment with a mixture of lysozyme and mutanolysin in protoplast buffer at pH 6.5 with different osmotic stabilizers. The protoplasts were regenerated on deMan, Rogosa and Sharpe (MRS) with various osmotic stabilizers. Maximum protoplast formation was obtained in protoplast buffer with sucrose as an osmotic stabilizer using a combination of lysozyme (1 mg/ml) and mutanolysin (10 μg/ml). Maximum protoplast regeneration was obtained on MRS medium with sucrose (0.5 M) as an osmotic stabilizer. The regeneration medium was also applicable to other species of lactobacilli as well. This is, to our knowledge, the first report on protoplast formation and efficient regeneration in case of L. delbrueckii.     

A landscape of shifting-mosaic steady state in Lassen Volcanic National Park,California

It is generally perceived that landscape patterns or textures in a given protected area are spatially stationary. The findings of this study suggest that this common perception is only partially correct. Over the course of 52 years, equilibrium in landscape shifting was detected using digital data for the Lassen Volcanic National Park (USA). Vertical aerial photographs taken of the park in 1941 were geo-referenced with the digital orthophoto quarter quadrangle (DOQQ) images of the same area from 1993 to identify landscape compositions and to measure change. Spatial analysis was used to observe pattern changes over time. The results suggested that landscape development maintained equilibrium while patches were in various stages of a successional sequence. The total area of each landscape component held steady, although over time patches throughout the landscape changed—a shifting-mosaic steady state (SMSS). These findings reflect the limitations of contemporary environmental conservation theory. They also suggest the importance of considering landscape change in policies that currently govern park planning and management.     

Immunohistochemical and electron microscopic identification of serotonin, melatonin and beta-endorphin in the granules of natural killers

The ability of serotonin, melatonin and beta-endorphin synthesis by secreting granules of natural killer cells (NK cells) was established by immunohistochemical method. It was shown that cytotoxic effect of NK cells can be to a certain extent related to the presence of secreting granules. A possible direct contribution of NK cell-synthesized hormones to the natural killer antitumour effect is discussed.     

Lipolytic and Esterolytic Activities in Posterior Lingual Glands of Rat: A Histochemical Study

Catalytic activities of lingual lipase were investigated by enzyme histochemistry in post-mortem tongues from male rats. Sections of fresh-frozen or formalin-calcium fixed tissue were incubated with naphthol-AS-nonanoate and α-naphthyl acetate substrate mixtures. The effects of pH level, sodium taurocholate activator and E600 inhibitor were also examined. The use of cryostat sections of tissues fixed in formalin-calcium and of nonanoate substrate within the range of pH 4.4–6.4, were optimal for localizing maximum reaction product, captured by Fast Blue BB, in acini and demilunes of the posterior deep and superficial lingual glands respectively. The reaction product corresponded with the distribution of secretory granules and failed to develop when taurocholate was omitted from the incubation medium. Similarly localized E600-resistant reaction product occurred with the acetate substrate and hexazotized New Fuchsin at pH 7.4, in the absence of taurocholate. Lipase and conventional esterase activities appear to be superimposed in posterior lingual glands of rat. The ability of their acini and demilunes to hydrolyse nonanoate substrate at an acidic pH optimum, when activated by sodium taurocholate, seems attributable to lipase destined for secretion into saliva – hence convenient for routine histochemical identification of the enzyme.     

Packing of ribosomes in crystals from the lizard Lacerta sicula

The packing of ribosomes in the large crystalline sheets found in the lizard Lacerta sicula has been investigated by electron microscopy. The ribosomes in each of the two layers composing a sheet are organised as tetramers on a P4 space group lattice. The two layers face in opposite directions and tend to be related to one another crystallographically, generating a family of P422 crystals of different unit cell dimensions. The projected structure of one layer was determined from negatively stained, isolated sheets by separating the contributions from each layer in Fourier transforms computed from electron micrographs. Comparison of the projection map with other, low resolution, analyses of images of isolated eukaryotic ribosomes indicates that the large subunit- small subunit axis lies approximately parallel to the plane of the sheet.     

In vivo and in vitro sugar transport in frog intestine

In the frog intestine, both in vitro and in vivo, experiments were carried out in order to increase knowledge of the mechanism of sugar exit across the basolateral membrane of the enterocyte. The frog intestine was chosen because it lacks crypt cells and, consequently, any external fluid circuit mechanism during sugar transport can be avoided. Therefore, the sugar concentration in the absorbate collected on the serosal side is likely to be similar to that present underneath the basolateral membrane of the enterocyte. Under this condition, cell and absorbate sugar concentrations are similar; yet there is a concomitant net transintestinal sugar transport. Moreover, in in vivo experiments a net transintestinal sugar transport takes place even against a concentration difference. These results suggest that sugar exit across the basolateral membrane is not simply due to a chemically facilitated diffusion.