An airlift loop reactor for the transformation of steroids by immobilized cells

Summary The flow behaviour of calcium alginate beads in an airlift reactor (ALR) with external loop was dependent on the airflow rate into and the amount of beads in the reactor. The performance of immobilizedArthrobacter simplex for the ¹-dehydrogenation of hydrocortisone in the ALR compared favourably to that in a stirred tank reactor. The physical stability of the calcium alginate beads was significantly greater in the ALR.     

Heterogeneity of globin protein synthesis in bone marrow cells of patients with homozygous beta-thalassemia from Tadzhikistan

The synthesis of globin proteins in blood reticulocytes of homozygous beta-thalassemic patients from Tadzhikistan has been previously studied. beta-thalassemia with sharp repression of beta-globin protein synthesis (alpha/beta greater than 10) has been shown to be most representative for the region. In this work, the synthesis of globin proteins has been studied in bone marrow cells of homozygous beta-thalassemic patients. Comparison of data on globin synthesis in bone marrow cells and in blood reticulocytes of the patients has revealed that in some cases the disbalance of chain synthesis in both cell types is equal. In other cases the disbalance in bone marrow cells is less than in blood cells, indicating the instability of beta-globin mRNA that is partially degrading in the process of cell maturation. Homozygous beta-thalassemic cases with low content of Hb F in blood cells (5-10%), with substantial disbalance of alpha and beta-globin synthesis and marked production of gamma-globins in bone marrow cells and in blood reticulocytes are of special interest. It has been assumed that parallel to beta-thalassemia some instability of gamma-globin proteins takes place in these patients.     

Filtration of a yeast suspension using an enclosed microporous metal filter

Summary A microporous (3 m) metal filter was very efficient for the recovery of Saccharomyces cerevisiae from a suspension. The filtration could be described by a cake filtration model, the cake resistance being dependent on the pressure drop applied and the concentration of bodyfeed added. The mean filtration capacity was 0.4 m³/m² h.     

Optimal sex ratio as a function of EGG incubation temperature in the crocodilians

Recently, there has been a growing consensus as to the adaptive significance of temperature-dependent sex determination in the Crocodilia. The observationally and experimentally motivated hypotheses are that male fitness depends more strongly on quality of incubation environment than female fitness, and that there is a strong correlation between a female's egg incubation temperature choice and her own egg incubation temperature. A population genetics model based on these hypotheses is derived. A method for finding the optimal sex ratio as a function of temperature, which is an evolutionary stable strategy (ESS), is stated and applied under various assumptions. This extends ESS theory to thefunctional case. Cases where there is no ESS and the population sex ratio oscillates in evolutionary time are discovered. Numerical computation is needed to solve the full problem and the resulting optimal sex ratio is compared to laboratory sex ratio data. The general pattern of TSD in crocodilians (female-male-female with female biased overall sex ratio) agrees well with the theory, but details of the pattern are problematic.     

Influence of L-serine-O-phosphate on synaptic transmission in afferent synapses of the ampullae of Lorenzini of skates

The method of superfusion of the basal membranes of the ampullae of Lorenzini of skates was used to investigate the influence of L-serine-O-phosphate (SOP) on the background and evoked activity of afferent nerve fibers, as well as on the effects of application of agonists: exciting amino acids — L-glutamate (L-GLU), kainate (KA), quisqualte (Q), and N-methyl-D-aspartate (NMDA). It was found that SOP (threshold concentration 10^–7 M) had an inhibiting effect on the background and evoked activity of the nerve fibers; depending on the concentration it decreased the stimulatory effects of L-GLU and NMDA and did not change the responses due to application of KA and Q. The data obtained suggest that the effects of SOP observed in the ampullae of Lorenzini are associated with its interaction with NMDA-type amino acid receptors.I. P. Pavlov Institute of Physiology, Academy of Sciences of the USSR, Leningrad. Translated from Neirofiziologiya, Vol. 23, No. 4, pp. 387–391, July–August, 1991.     

Isolation and Characterization of Opioid Peptides from Rabbit Cerebellum

The rabbit cerebellum has been shown to contain significant quantities of opioid receptors consisting of both mu- and kappa-subtypes. To determine the nature of the endogenous opioid ligands in this tissue, extracts from rabbit cerebellum were separated by various chromatography techniques and fractions were assayed initially for opioid peptides with a radioimmunoassay capable of detecting all peptides with an amino-terminal Tyr-Gly-Gly-Phe sequence. This sequence is common to all mammalian opioid peptides and is critical for recognition by all known opioid receptors. Each of the three immunoreactive opioid peptide peaks detected was purified to homogeneity and subjected to amino acid composition and sequence analysis. One peak was analyzed further by mass spectrometry. This identified the major opioid peptides in the cerebellum as [Met5]enkephalin, [Leu5]enkephalin, and heptapeptide [Met5]enkephalyl-Arg6-Phe7. The comprehensiveness of this initial detection scheme in identifying biologically active opioid peptides was substantiated through subsequent analysis. Using specific radioimmunoassays for representative opioid peptides of the three opioid systems currently known, no other peptides of either the proenkephalin, proopiomelanocortin, or prodynorphin series were detected in any appreciable amounts. Collectively, these results are consistent with the position that rabbit cerebellar opioids are derived from proenkephalin. However, given that no appreciable quantities of either [Met5]enkephalyl-Arg6-Arg7-Val8-NH2 (metorphamide) or [Met5]enkephalyl-Arg6-Gly7-Leu8 were detected suggests that rabbit proenkephalin may have a slightly altered sequence and/or is differentially processed relative to other mammalian species studied.     

The collicular recess organ: Evidence for structural and secretory specialization of the ventricular lining in the collicular recess

Summary The collicular recess organ and adjacent portions of the collicular recess were studied by light microscopy, scanning electron microscopy and transmission electron microscopy. In the collicular recess, the ventricular wall contains folds and is well vascularized. The adluminal ependymal cells generally bear kinocilia and microvilli on their ventricular surface. Among the cilia, many secretory droplets, some axons, and few supraependymal cells are seen. Various stages of apocrine ependymosecretion are observed. In addition to tanycytes, coelocytes are found scattered throughout the ependymal lining of the collicular recess. Coelocytes, characterized by lumina containing cilia and a few microvilli, are accumulated in ependymal and hypependymal positions of the collicular recess organ at the roof of the collicular recess.Supported by PHS grants NS 09914 and T32 CA09156. We thank Dean Wyrick and John McNeill, Jr., for their technical assistanceNRSA Postdoctoral Trainee