The role of CcTpt1 in scale and early embryo development in common carp (Cyprinus carpio, Cyprinidae)

The full length cDNA sequence of the Tpt1/TCTP (Tumor protein, Translationally-controlled1) gene was identified from Common Carp (Cyprinus carpio, Cyprinidae), and was designated as CcTpt1 gene. The CDS is 510 bp and encodes a 170-amino acid peptide with a typical Tpt1 signature 2 domain, and is a typical Tpt1 protein. The deduced amino acid sequence of Tpt1 shared significant identity with the Tpt1 from other animals. A phylogenetic tree analysis revealed that the Common Carp Tpt1 protein has the closest genetic relationship and evolutional distance with Tpt1 from Medaka (Oryzias Latipes). Analysis by RT-PCR showed that the Tpt1 mRNA was detected in heart, liver, gill, kidney, muscle and skin. In embryogenesis, the Tpt1 mRNA was expressed gradually stronger from two-cell stage until prim-5 stage by whole-mount in situ. In larval stage, the Tpt1 was specifically expressed at eyes and brain, later at the ear stone, intestines, gills and internal organs. In addition, the Tpt1 was also found to be expressed in skin matrix being developed into scales and gradually disappeared when the scales were fully formed. These data suggested that the CcTpt1 may play important roles in early embryogenesis and scale initiation in fish.     

The effects of physical parameters on laser-induced breakdown spectroscopy analysis of intact tablets

With the advent of the Food and Drug Administration initiatives to investigate and encourage the use of process analytical technologies, laser-induced breakdown spectroscopy (LIBS) is considered an excellent analytical tool to understand the processability of solid dosage form. In this article, the feasibility of the LIBS system for quantitation of active drug within a solid dosage form, as well as the effects of various physical parameters on its signal, is investigated. A model drug containing chlorine and sulfur was used. The examination of the specificity and reproducibility of the measurements led to the use of chlorine and carbon as the internal standard. An overall relative SD of 1.1% for the signal was found. For quantitation purposes, calibration curves using compound-X in formulated tablets were generated. It was found that curves generated from roller-compaction tablets generally gave higher LIBS signal than those generated using direct-compressed (DC) process. To investigate these differences, effect of LIBS signals from several physical properties of the tablets were examined. It was found that unmilled compound-X used in the manufacture of the tablets gave a LIBS signal 30% lower than when milled compound-X was used. However, by using multiple crushing-recompression DC process of the milled compound-X, the LIBS results were comparable with those found from both processed tablets using milled compound-X. Other physical parameters, such as wide ranges of granule size and tablet hardness found in the typical manufacturing process, had limited effect on the LIBS signal. From these results, it was noted that for accurate quantitation, it is necessary to use the same physical properties of compound-X and the same manufacturing process in the calibration standards as the actual samples.     

Effects of the sinR and degU32 (Hy) mutations on the regulation of the aprE gene in Bacillus subtilis

The aprE gene of Bacillus subtilis codes for the serine alkaline protease known as subtilisin. Its expression is regulated by a complex network of activators and repressors that includes the products of hpr, degU and sinR. In order to understand the effect of these gene products on subtilisin expression, strains carrying combinations of the degU32(Hy), hpr2 and sinR null mutations, were constructed. We found that in all the genetic backgrounds tested, the sinR null mutation decreased aprE expression. Also, by measuring alkaline phosphatase synthesis and the formation of heat-resistant spores, as indicators of sporulation, we found that some of the mutant strains showed alterations in the sporulation process. These results suggest that these alterations are partially responsible for some of the observed changes in aprE expression. Received: 12 January 1996 / Accepted: 7 July 1996     

Flexible Memory Networks

Networks of neurons in some brain areas are flexible enough to encode new memories quickly. Using a standard firing rate model of recurrent networks, we develop a theory of flexible memory networks. Our main results characterize networks having the maximal number of flexible memory patterns, given a constraint graph on the network’s connectivity matrix. Modulo a mild topological condition, we find a close connection between maximally flexible networks and rank 1 matrices. The topological condition is H ₁(X;ℤ)=0, where X is the clique complex associated to the network’s constraint graph; this condition is generically satisfied for large random networks that are not overly sparse. In order to prove our main results, we develop some matrix-theoretic tools and present them in a self-contained section independent of the neuroscience context.