Effect of low ambient temperature on protein turnover and heat production in chicks

1. Effect of low ambient temperature on protein turnover in the liver and whole body was investigated in chicks together with the contribution of protein synthesis to the total heat production. 2. Both protein synthesis and degradation in the whole body were increased, the latter to a larger extent, at low ambient temperature (LT, 22 degrees C) compared with adequate temperature (AT, 30 degrees C). Liver protein synthesis was not significantly altered by the temperature treatment. 3. The total heat production of LT group was as high as 160% of the AT group. 4. The increased heat production due to enhanced whole-body protein synthesis accounted for only 1.4% of the heat increment in thermogenesis at low ambient temperature, suggesting that protein synthesis would contribute little, if any, to cold-induced thermogenesis in chicks.     

Late Pleistocene molluscan assemblages from the coral reefs of the Kenya coast

Since the Last Interglacial, there have been profound changes in the nature of the fringing reef along the Kenya coast. These are most apparent in the back-reef region where a marked decline in habitat diversity has led to a significant reduction in the variety of molluscan assemblages. Despite dramatic changes in the composition of these assemblages, very few species have become extinct. The four late Pleistocene species apparently missing from the Recent fauna of the Kenya coast still occur further east in the Indonesia-West Pacific region. There is evidence to suggest that range retractions from the periphery to the core region occurred at the same time in other parts of the Indo-Pacific province too. The province's margins may well have been more susceptible to fluctuations in certain environmental parameters, such as temperature, during the Pleistocene climatic cycles.     

Characterization of a cDNA clone encoding a basic protein, TP2, involved in chromatin condensation during spermiogenesis in the mouse

A cDNA clone encoding a small cysteine and serine-rich basic protein has been isolated from a mouse testis cDNA library. This cDNA clone encodes the mouse homologue of a protein involved in the initial phases of condensation of chromatin during spermiogenesis in rats, TP2, based on similarities in the sequence of the carboxyl terminus, composition, molecular weight, and electrophoretic mobility. Mouse TP2 can be divided into a highly basic domain comprising about one-third of the polypeptide chain at the carboxyl terminus and a much less basic domain comprising the remaining two-thirds at the amino terminus. The 5' end of the mouse TP2 mRNA contains two in-phase initiation codons both of which may be used generating two polypeptides which differ in length at the amino terminus. Southern blots demonstrate that there is a single copy of the TP2 gene in the mouse genome and Northern blots demonstrate that the polyadenylated TP2 mRNA is present at high and essentially equal levels in early and late haploid cells, and that it is virtually absent from meiotic cells.     

Structural analysis of covalently labeled estrogen receptors by limited proteolysis and monoclonal antibody reactivity

We have used limited proteolysis of affinity-labeled estrogen receptors (ER), coupled with antireceptor antibody immunoreactivity, to assess structural features of ER and the relatedness of ER from MCF-7 human breast cancer and rat uterine cells. MCF-7 ER preparations covalently labeled with [3H]tamoxifen aziridine [( 3H]TAZ) were treated with trypsin (T), alpha-chymotrypsin (C), or Staphylococcus aureus V8 protease prior to electrophoresis on sodium dodecyl sulfate gels. Fluorography revealed a distinctive ladder of ER fragments containing TAZ for each protease generated from the Mr 66,000 ER: for T, fragments of 50K, 38K, 36K, 31K, 29K, and 28K that with longer exposure generated a 6K fragment; for C, fragments of 50K, 38K, 35K, 33K, 31K, 19K, and 18K that with longer exposure generated 14K and 6K fragments; and for V8, ca. 10 fragments between 62K and 28K. Two-dimensional gels revealed charge heterogeneity (two to three spots between pI 5.5 and 6.2) of the 66K ER and the T-generated 28K meroreceptor form. Immunoblot detection with the primate-specific antibody D75P3 gamma revealed that all immunoreactive fragments corresponded to TAZ-labeled fragments but that some small TAZ-labeled fragments (V8-generated forms less than 47K and T-generated forms less than 31K) were no longer immunoreactive. In contrast, use of the antibody H222Sp gamma revealed a correspondence between TAZ-labeled and immunoreactive fragments down to the smallest fragments generated, ca. 6K for T and C and 28K for V8. MCF-7 nuclear and cytosol ER showed very similar digest patterns, and there was a remarkable similarity in the TAZ-labeled and H222-immunoreactive fragments generated by proteolysis of both MCF-7 and rat uterine ER. These findings reveal great structural similarities between the human (breast cancer) and rat (uterine) ER and between nuclear and cytosol ER, indicate charge heterogeneity of ER, and allow a comparison of the immunoreactive and hormone attachment site domains of the ER. The observation that T and C generate a ca. 6K TAZ-labeled fragment that is also detectable with the H222 antibody should be of interest in studies determining the hormone binding domain of the ER and in amino acid sequencing of this region.     

Adaptation of the tetrazolium method for testing the seed viability, and scanning electron microscopy study of some Western European orchids

A modified tetrazolium method was formulated for use with seeds of Western European orchids. The sequence of treatments which gave the highest percentage of coloured (i.e. viable) embryos was: (1) pretreatment in a solution of 5% (w/v) Ca(OCl)₂+ 1% (v/v) Tween-80, (2) soaking for 1 day in sterile water, (3) the classical tetrazolium test. The optimal duration of the pretreatment in Ca(OCl)₂+ Tween-80 depends upon the species, and to investigate the effect a scanning electron microscopy study was performed on the testa of 3 species. For a given species, the optimal pretreatment period was not affected by the year of harvest or the source of the seed lots.     

Preservation of sorghum plant portions harvested,processed and ensiled at ten stages of maturity

Two varieties of grain sorghum were harvested at 10 intervals from 35–189 days post planting. Leaf, stem and head portions were separated before being prepared for chemical analysis or ensiled for 30 days in 1-1 silos with or without preservatives. The taller variety (FS-1b) accumulated 60% more dry matter than ORO-T with advancing plant maturity, while whole plant crude protein content decreased from near 20 to less than 7% for both varieties. Dry matter ensiling loss (DMEL) was different (P < 0.05) for each plant portion, but was lower and less variable after the 77-day harvest. Immature leaves and heads resulted in the greatest average DMEL of 31 and 24%, respectively. Propionic acid decreased DMEL, while an ammonia solution was ineffective when compared to control leaf, stem and heads. The DMEL of leaves was influenced (P < 0.05) by a varietal × modulus of fineness interaction while the stem exhibited an interaction with plant maturity × modulus of fineness. Modulus of fineness was not associated with levels of organic acid production in silages, but plant maturity significantly influenced acetic, propionic and butyric acid production in heads. These data indicated that numerous combinations of silage preservation techniques affected DMEL of sorghum plant portions at different maturities.     

Extracellular matrix metabolism by chondrocytes 7. Evidence that L-glutamine is an essential amino acid for chondrocytes and other connective tissue cells

THe incorporation of [³H]glycine into acid-insoluble protein and of [³H]acetate into glysoaminoglycans by cultured chick chondrocytes was stimulated by the addition of L-glutamine to the incubation medium. The effect of exogenous L-glutamine on protein synthesis was studied further by examining changes in the sedimentation patterns on sucrose gardients of ribosomes isolated from chondrocytes incubated in presence and absence of L-glutamine. It was found that the absence of L-glutamine caused a disaggregation of poly-ribosomes that was reversed by the addition of this amino acid to the culture medium. No detectable glutamine synthetase activity could be measured in avian articular cartilage. These results indicate that L-glutamine is an essential amino acid for cartilage in that an extracellular supply of this amino acid is required for the maintenance of protein and glycosaminoglycan synthesis. A dependence on L-glutamine was also demonstrated for other avain connective tissues.