Nutrient Leaching and End Product Accumulation in Plastic Composite Supports for L-(+)-Lactic Acid Biofilm Fermentation

Investigations on the leachate bioavailability, leaching rate, and lactic acid accumulation properties of plastic composite supports (PCS) were essential for large-scale or long-term lactic acid fermentation. Leachates from PCS and polypropylene discs (controls) were analyzed by the micro-Kjeldahl method; by absorbances at 260, 275, and 280 nm; and by bioassays with Lactobacillus casei subsp. rhamnosus (ATCC 11443). The amount of leached nitrogen in a 20-ml initial soaking solution had a high correlation with the soaking solution's cell density (r = 0.87) and absorbance at 260 nm (r = 0.95). Leaching rates of various PCS were evaluated by 20 20-ml simulated repeated-batch fermentations (RBF). PCS with only yeast extract as the minor agricultural ingredient had a high leaching rate and leached out 51 to 60% of the total nitrogen during the first RBF. PCS blended with dried bovine albumin, dried bovine erythrocytes, and/or soybean flour had slowed nutrient leaching (20 to 30% of the initial leached nitrogen). Hence, they could still maintain 1 g of lactic acid per liter and measurable cell density (absorbance at 620 nm, 0.4 to 0.6) at the 20th 20-ml RBF. Lactic acid accumulation properties of PCS were evaluated by soaking the supports in a 30% lactic acid solution for 72 h at 45(deg)C. The lactic acid-soaked supports were rinsed three times and then heat treated (121(deg)C, 15 min) in 15 ml of deionized water. The results showed that lactic acid accumulation in PCS was mainly due to absorption and had no correlation with lactic acid production or biofilm formation.     

Photovoltaic Materials and Devices Based on the Alloyed Kesterite Absorber (AgxCu1–x)2ZnSnSe4

The photovoltaic absorber Cu₂ZnSn(S_xSe_1–x)₄ (CZTSSe) has attracted interest in recent years due to the earth‐abundance of its constituents and the realization of high performance (12.6% efficiency). The open‐circuit voltage in CZTSSe devices is believed to be limited by absorber band tailing caused by the exceptionally high density of Cu/Zn antisites. By replacing Cu in CZTSSe with Ag, whose covalent radius is ≈15% larger than that of Cu and Zn, the density of I–II antisite defects is predicted to drop. The fundamental properties of the mixed Ag‐Cu kesterite compound are reported as a function of the Ag/(Ag + Cu) ratio. The extent of band tailing is shown to decrease with increasing Ag. This is verified by comparing the optical band gap extrapolated from transmission data with the position of the room‐temperature photoluminescence peak; these values converge for the pure‐Ag compound. Additionally, the pinning of the Fermi level in CZTSSe, attributed to heavy defect compensation and band tailing, is not observed in the pure‐Ag compound, offering further evidence of improved electronic structure. Finally, a device efficiency of 10.2% is reported for a device containing 10% Ag (no antireflection coating); this compares to ≈9% (avg) efficiency for the baseline pure‐Cu CZTSe.     

Transient catecholaminergic (TC) cells in the vagus nerves and bowel of fetal mice: relationship to the development of enteric neurons

Catecholaminergic cells are transiently present during development of the fetal murine bowel. These transient catecholaminergic (TC) cells appear at Day E10, but by Day E13 can no longer be detected. In order to evaluate the hypothesis that these cells are the precursors of enteric neurons, we investigated the possibilities that TC cells coexpress neuronal and catecholaminergic markers, that they can be found along the presumed path followed by crest-derived cells migrating to the gut, and that they are proliferating. TC cells were identified immunocytochemically using polyclonal or monoclonal antibodies to tyrosine hydroxylase (TH). At Day E9.5, TH-immunoreactive cells were observed to be present along the wall of the primordial esophagus in lines that extended from the developing nodose ganglia down to the boundary of the stomach. At Day E9.5, TC cells were absent from the remaining foregut. These lines of esophageal TH-immunoreactive cells became continuous with similar cells in the wall of the stomach and duodenum on Day E10. Coincident expression of neurofilament immunoreactivity was seen in all of the esophageal TH-immunoreactive cells present at Day E9.5, as well as in the entire set of esophageal and lower enteric TH-immunoreactive cells present at Day E10 (or later); moreover, at Days E9.5 and E10, all of the neurofilament-immunoreactive cells in the esophagus, stomach, or duodenum were also TH-immunoreactive. In contrast, neurofilament immunoreactivity was not expressed by the endodermally derived pancreatic duct and islet cells, which were also TH-immunoreactive; nor could expression of neurofilament immunoreactivity be detected in the TH-immunoreactive cells of the nodose ganglia. It was not until Day E11 that neurofilament-immunoreactive cells, which did not coexpress TH immunoreactivity (the definitive phenotype of enteric neurons) began to appear in the gut. Vagal axons reached as far distally as the nodose ganglion on Day E9.5, the esophagogastric junction on Day E10, and did not enter the stomach until Day E11. When the vagus nerves reached their level, the TH-immunoreactive cells in the wall of the esophagus came to lie among the nerve fibers. TH-immunoreactive cells are thus present on the pathway ultimately followed by the vagus nerves, but they develop before vagal fibers reach their level. The vagal TH-immunoreactive cells, therefore, are probably not initially migrating on vagal fibers, but appear instead to be overtaken by the descending vagus nerves.(ABSTRACT TRUNCATED AT 400 WORDS)     

Varicella-zoster virus glycoprotein oligosaccharides are phosphorylated during posttranslational maturation.

Varicella-zoster virus (VZV)-infected human embryonic lung fibroblasts (HELF) do not release infectious virions into their growth medium. Extracellular virions are pleomorphic, suggesting that they are partially degraded before their release from cells. To examine the intracellular pathway of viral maturation, [2-3H]mannose-labeled virus-encoded glycoproteins were isolated from VZV-infected HELF. Oligosaccharides attached to the glycoproteins were processed to complex-type units, some of which were phosphorylated. The major intracellular site of accumulation of VZV gpI was found to be perinuclear and to correspond to that of the cation-independent mannose 6-phosphate (Man 6-P) receptor. Subsets of VZV-containing cytoplasmic vacuoles were coated, Golgi-associated, or accessible to endocytic tracers. Phosphorylated monosaccharides protected HELF from the cytopathic effect of VZV in proportion to their ability to block Man 6-P receptor-mediated endocytosis. These data suggest that the unusual phosphorylated oligosaccharides mediate an interaction between VZV and Man 6-P receptors of the host cell; this interaction may be responsible for withdrawal of newly synthesized virions from the secretory pathway and for their diversion to prelysosomal structures.     

A comparison of the genome organization of capripoxvirus with that of the orthopoxviruses.

Comprehensive comparisons of genome organizations for poxviruses of different genera have not previously been reported. Here we have made such a comparison by cross-hybridizing genome fragments from capripoxvirus KS-1 and vaccinia virus WR (VV). This showed that a 100- to 115-kilobase (kb) centrally placed section is essentially colinear in organization in the two viruses and that a small region has translocated between the ends of one or other of the genomes during their divergence. No cross-hybridization could be detected between VV DNA and the respective left- and right-hand terminal 8 and 25 kb of capripoxvirus DNA or between capripoxvirus DNA and the respective left- and right-hand terminal 38 and 35 kb of VV DNA. By using the cross-hybridization data, a 4-kb fragment of KS-1 DNA was identified, which corresponds to the regions of the cowpox virus and VV genomes containing genes for the orthopoxvirus A-type inclusion body protein ("ATI"). The sequence of the KS-1 DNA fragment contains homologs of genes which are on either side of the orthopoxvirus ATI genes but contains no homolog of the ATI gene itself. Overall, these results show that the pattern of genomic conservation and variation between two poxvirus genera reflects the pattern within the orthopoxvirus genus but that, as observed previously, individual genes may not be present in genomic regions which are otherwise conserved in organization.     

Characterization of Plant Alcohol Dehydrogenase

The final activity of the alcohol dehydrogenase (E.C.1.1.1.1, abbreviated ADH) from germinating pea, isolated by fractionating with ammonium sulphate, chromatography on DEAE cellulose and gel filtration, was 80,000, from bean 25,000 and from lentil 13,500 units per mg protein. Molecular weights of the ADHs are close to each other: pea and bean ADH 60,000, lentil ADH 70,000. The K_m values are mutually similar with three enzymes, i.e. of the order of 10⁻⁴M for NAD and 10⁻²M for ethanol. The pH optima lie in the alkaline region. These enzymes catalyse oxidation of a number of monovalent alcohols. At temperatures above 60°C the enzymes are thermally unstable. Stability is enhanced slowly by ethanol but not by NAD. Pyrazol, imidazol and pyridine inhibit plant ADH similarly to the enzyme from horse liver. There is a similarity between plant alcohol dehydrogenases and animal and yeast enzymes.     

Splenic regulation of lymphocyte trapping in lymph nodes draining tumor grafts.

We measured the trapping of 51chromium-labeled splenic lymphocytes in the lymph nodes and spleens of tumor-inoculated mice at various intervals after inoculation. Both histocompatible and incompatible tumors were studied. Significant trapping occurred in the draining lymph nodes over the entire course of the experiments. The splenic trapping response commenced very early after transplantation and abated after a few days. The magnitude of the lymph node trapping response correlated with the magnitude of antigenic difference between tumor and host. Splenectomy before tumor inoculation had bidirectional effects; it caused a marked augmentation of the trapping response in the early period after tumor inoculation, which declined with time so that late after tumor inoculation, splenectomized animals trapped less well than intact controls. Tumor resection always led to a rapid fall in the trapping response in normal mice. However, tumor resection at the time of the peak trapping response of splenectomized mice produced no change. These results support the notion that lymphocyte trapping is a valid and useful monitor of the immune response to tumors. They also serve to reemphasize the important regulatory role of the spleen plays in the immune response to tumor-associated antigens by demonstrating a new parameter of splenic control; regulation of lymphocyte traffic in response to antigenic stimuli.     

Fungitoxicity of 1,4-naphthoquinones to Candida albicans and Trichophyton mentagrophytes.

Twenty-one substituted 1,4-naphthoquinones and five 8-quinolinols and copper(II) chelates were tested for antifungal activity against Candida albicans and Trichophyton mentagrophytes. Compounds containing electron-releasing or weak electron-withdrawing groups in the 2 and 3 positions of the 1,4-naphthoquinone ring were the most active against C. albicans at pH 7.0 in the presence of beef serum in the following order: 2-CH3O = 2,3-(CH3O)2 greater than 2-CH3 greater than 2-CH3S greater than 2-NH2 greater than 2,6-(CH3)2. For T. mentagrophytes under the same conditions the inhibitory 1,4-naphthoquinones contained the substituents 2-CH3O greater than 2,3-(CH3O)2 greater than 2-CH2S greater than 2-CH3 greater than 2-CH3(NaHSO3) greater than 2-NH2 greater than 2-C2H5S, 3-CH3 greater than 2,6-(CH3)2 greater than 2,3-CL2 greater than 5,8-(OH)2.