Differences in Lipid Composition and Proliferative Activity of Rat Hepatoma-27 Depending on the Target Organ

Proliferative activity and lipid composition (phospholipids and gangliosides) were studied in rat hepatoma-27 transplanted subcutaneously or intrahepatically (as models for primary and metastasizing tumors). The mitotic index of subcutaneously transplanted hepatoma far exceeded that of the intrahepatically transplanted tumor. The overall amounts of both phospholipids and gangliosides increased appreciably in the subcutaneously growing hepatoma (in contrast to the intrahepatically growing tumor) in comparison to the control hepatic tissue. The ganglioside composition in the tumors differs from that in the liver: ganglioside GD3 appears, whereas gangliosides GD1b and GT1b decrease in amount in the intrahepatic tumor compared to the control liver and disappear in the subcutaneously transplanted hepatoma. In both tumor types, the amounts of both phosphatidylethanolamine and sphingomyelin exceed the control values. Comparison of these results with previously reported data concerning the phospholipid and ganglioside composition in the regenerating rat liver indicates that the difference in the lipid composition between the subcutaneously and intrahepatically growing hepatomas-27 is due to their different proliferative status and also their microenvironment.     

First Philippine record of the parasitoid,Comperiella sp. (Hymenoptera: Encyrtidae): a potential biocontrol agent against Aspidiotus rigidus (Hemiptera: Diaspididae)

The encyrtid genus Comperiella Howard has so far not been reported in the Philippines, where there is currently an outbreak of the coconut scale insect Aspidiotus rigidus Reyne particularly in the southern parts of the island of Luzon and in some areas in Mindanao. Among Comperiella species, only C. unifasciata Ishii has been reported as a parasitoid of A. rigidus. We report not only new sightings of this parasitoid genus in the Philippines from surveys conducted in parts of the provinces of Laguna and Batangas, but also the discovery of a possibly new species that, like C. unifasciata, has been found to parasitize A. rigidus at a high rate. These findings have presented a potential of biological control against the coconut scale insect problem that has threatened the coconut industry in the country.     

Glutamic Acid Signal Synchronizes Protein Synthesis Kinetics in Hepatocytes from Old Rats for the Following Several Days. Cell Metabolism Memory

The kinetics of protein synthesis was investigated in primary cultures of hepatocytes from old rats in serum–free medium. The rats were fed mixed fodder supplemented with glutamic acid and then transferred to a regular mixed fodder. The amplitude of protein synthesis rhythm in hepatocytes isolated from these rats increased on average 2–fold in comparison with the rats not receiving glutamic acid supplement. Based on this indicator reflecting the degree of cell–cell interactions, the cells from old rats were not different from those of young rats. The effect was preserved for 3–4 days. These results are discussed in connection with our previous data on preservation of the effect of single administration of gangliosides, noradrenaline, serotonin, and other synchronizers on various cell populations. In contrast to the other investigated factors, glutamic acid is capable of penetrating the blood–brain barrier, which makes its effect possible not only in the case of hepatocytes and other non–brain cells, but also in neurons.     

The effect of the cell microenvironment on cell functions associated with tumor promotion and progression

To study the role of the cellular microenvironment in tumor promotion and progression, transformed cells of rat embryonic fibroblasts (CL-1 clone) were transplanted into transgenic immunodeficient mice and cells of the formed tumor were converted into culture (CL-1-1 cells). Cells before and after transplantation were compared in morphology, growth rate, and permeability of intercellular gap junction. CL-1-1 cells were shown to have a changed morphology, to grow faster than the CL-1 cell, and to have no contact inhibition. In the G₁ phase of the cell cycle, there were many more CL-1 than CL-1-1 cells, whereas, in the G₂ and M phases, CL-1-1 cells were predominant. The permeabilities of the gap junction in the CL-1 and CL-1-1 cells were approximately the same. It was concluded that the cell microenvironment can stimulate tumor promotion and tumor progression upon transplantation of transformed cells into immunodeficient animals.     

重庆市蕨类植物区系调查和分析

重庆市有野生蕨类植物47科120属604种(含变种及以下分类单位)。其科属优势明显,其中蹄盖蕨科、金星蕨科、鳞毛蕨科和水龙骨科4个科包含了49属337种,占重庆市蕨类植物属、种总数的40.83%和55.79%;特有现象明显,地方特有种十分丰富,中国特有种和地方特有种类分别达到164种和33种;蕨类植物区系具有古老、孑遗和原始性等特点,表现出一定的热带性质或热带亲缘。     

Influence of individual domains of the translation termination factor eRF1 on induction of the GTPase activity of the translation termination factor eRF3

Translation termination in eukaryotes is governed by two proteins belonging to class 1 (eRF1) and class 2 (eRF3) polypeptide release factors. eRF3 catalyzes hydrolysis of GTP to yield GDP and P_i in the ribosome in the absence of mRNA, tRNA, aminoacyl-tRNA, and peptidyl-tRNA and requires eRF1 for this activity. It is known that eRF1 and eRF3 interact with each other via their C-terminal regions both in vitro and in vivo. eRF1 consists of three domains—N, M, and C. In this study we examined the influence of the individual domains of the human eRF1 on induction of the human eRF3 GTPase activity in the ribosome in vitro. It was shown that none of the N, M, C, and NM domains induces the eRF3 GTPase activity in the presence of ribosomes. The MC domain does induce the eRF3 GTPase activity, but four times less efficiently than full-length eRF1. Therefore, we assumed that the MC domain (and very likely the M domain) binds to the ribosome in the presence of eRF3. Based on these data and taking into account the data available in the literature, a conclusion was drawn that the N domain of eRF1 is not essential for eRF1-dependent induction of the eRF3 GTPase activity. A working hypothesis is formulated that the eRF3 GTPase activity in the ribosome during translation termination is associated with the intermolecular interactions of GTP/GDP, the GTPase center of the large (60S) subunit, the MC domain of eRF1, and the C-terminal region and GTP-binding motifs of eRF3 but without participation of the N-terminal region of eRF1.     

Muscle transcriptomic analyses in Angus cattle with divergent tenderness

Beef tenderness contributes significantly to variation of beef palatability, and is largely influenced by various genetic and environmental factors. To identify candidate genes and pathways related to beef tenderness, we analyzed the longissimus dorsi (LD) muscle of Angus cattle that had different degrees of tenderness, measured by Warner-Bratzler shear force (WBSF). Microarray and RT-PCR analyses identified 53 genes that were differentially expressed in LD samples categorized as either tough or tender, including myosin, heavy chain 3 skeletal muscle embryonic (MYH3), myosin heavy chain 8 skeletal muscle perinatal (MYH8), guanylate binding protein 5 (GBP5), fatty acid binding protein 4 (FABP4), Stearoyl-coenzyme A desaturase (SCD), Fatty acid synthase (FASN), ubiquitin-like with PHD and ring finger domains 1 (UHRF1). Most of these genes are involved in lipid metabolism and skeletal muscle contraction. Employing Gene ontology (GO) and Ingenuity Pathway Analysis (IPA), several GO terms and pathways were found to be related to hydrolase, peptidase and GTPase activity, lipid metabolism, small molecule biochemistry, molecular transport, and tissue development. Overall, this analysis provides insight into the metabolic relationships between muscle biology and beef quality.     

The invariant uridine of stop codons contacts the conserved NIKSR loop of human eRF1 in the ribosome

To unravel the region of human eukaryotic release factor 1 (eRF1) that is close to stop codons within the ribosome, we used mRNAs containing a single photoactivatable 4-thiouridine (s(4)U) residue in the first position of stop or control sense codons. Accurate phasing of these mRNAs onto the ribosome was achieved by the addition of tRNA(Asp). Under these conditions, eRF1 was shown to crosslink exclusively to mRNAs containing a stop or s(4)UGG codon. A procedure that yielded (32)P-labeled eRF1 deprived of the mRNA chain was developed; analysis of the labeled peptides generated after specific cleavage of both wild-type and mutant eRF1s maps the crosslink in the tripeptide KSR (positions 63-65 of human eRF1) and points to K63 located in the conserved NIKS loop as the main crosslinking site. These data directly show the interaction of the N-terminal (N) domain of eRF1 with stop codons within the 40S ribosomal subunit and provide strong support for the positioning of the eRF1 middle (M) domain on the 60S subunit. Thus, the N and M domains mimic the tRNA anticodon and acceptor arms, respectively.