Effect of dietary lipid supplementation on progesterone concentration and reproductive performance in suckled beef cows

Using whole cottonseed as a lipid source, silage-based diets that were isocaloric and isonitrogenous yet varied in lipid level were fed to multiparous cows. In Experiment 1, 48 cows (n = 12 per treatment) were allotted to 1 of 4 treatments where diets were formulated to supply 3.9, 4.3, 5.3 and 6.3% of total lipid. In Experiment 2, 66 cows (n = 22 per treatment) were allotted to 1 of 3 treatments where diets were formulated to supply 3.1, 5.5 and 8.3% of total lipid. Length of the first ovarian cycle, length of the first normal estrous cycle, postpartum intervals to onset of ovarian luteal activity and to first estrus were not affected by diet (P>0.10) in either experiment. Mean progesterone (P(4)) concentrations for first normal estrous cycles were not different (P>0.10) in either experiment. Anestrous periods were divided into 3 phases for analyses: Phase I) parturition to onset of ovarian luteal activity, Phase II) first ovarian luteal activity and Phase III) first normal estrous cycle. No differences were observed in P(4) concentrations during any phase of the postpartum period. In conclusion, isocaloric and isonitrogenous diets with increasing levels of lipid had no effect on reproductive performance in suckled beef in these experiments.     

Synergistic interactions between XPC and p53 mutations in double-mutant mice: neural tube abnormalities and accelerated UV radiation-induced skin cancer

The significance of DNA repair to human health has been well documented by studies on xeroderma pigmentosum (XP) patients, who suffer a dramatically increased risk of cancer in sun-exposed areas of their skin [1] and [2]. This autosomal recessive disorder has been directly associated with a defect in nucleotide excision–repair (NER) [1] and [2]. Like human XP individuals, mice carrying homozygous mutations in XP genes manifest a predisposition to skin carcinogenesis following exposure to ultraviolet (UV) radiation [3], [4] and [5]. Recent studies have suggested that, in addition to roles in apoptosis [6] and cell-cycle checkpoint control [7] in response to DNA damage, p53 protein may modulate NER [8]. Mutations in the p53 gene have been observed in 50% of all human tumors [9] and have been implicated in both the early [10] and late [11] stages of skin cancer. To examine the consequences of a combined deficiency of the XPC and the p53 proteins in mice, we generated double-mutant animals. We document a spectrum of neural tube defects in XPC p53 mutant embryos. Additionally, we show that, following exposure to UV-B radiation, XPC p53 mutant mice have more severe solar keratosis and suffer accelerated skin cancer compared with XPC mutant mice that are wild-type with respect to p53.     

Macrophage colony-stimulating factor induces thrombospondin I production by cultured human macrophages

The role of colony-stimulating factors (CSFs) in regulating the synthesis of thrombospondin 1 (TSP1) by cultured human macrophages is investigated. Macrophage (M)-CSF is shown rapidly and transiently to induce two predominant species of TSP1 mRNA. One of these species was 3.2 kb in size and appeared to be specific to M-CSF-stimulated macrophages. Adherent M-CSF-treated macrophages are also shown to express abundant surface cell-associated TSP rapidly when examined by indirect immunofluorescence staining. Granulocyte-macrophage (GM)-CSF induced TSP1 mRNA at a later time point, and this was attributable to the effects of endogenous M-CSF induced by the GM-CSF; the GM-CSF-treated cells did not display surface-associated TSP after 3 hr of treatment. Analysis of the TSP1 protein synthesised by the M-CSF-treated macrophages revealed the expected trimeric form of the molecule. In addition, an unidentified 95-kDa protein was found to be covalently associated with immunoreactive TSP1, and this appeared to be specific to the macrophages as it was not found in TSP1 precipitated from other cell types. It is suggested that the induction of TSP1 by M-CSF may play an important role in the major physiological functions of macrophages. © 1995 Wiley-Liss, Inc.     

Changes in key regulatory enzymes of hepatic carbohydrate metabolism after glucose loading of starved rats

When glucose was given to starved rats there was an increase in both 6-phosphofructo 2-kinase and pyruvate kinase activity and a decrease in fructose 2,6-bisphosphatase activity 30 min and 60 min later. These changes were accompanied by an increase in glycogen deposition and by modest, but significant increases in fructose 2,6-bisphosphate levels at the same time. Metabolite measurements indicated that flux through 6-phosphofructo 1-kinase and pyruvate kinase were increased. These results suggest that although glycogen deposition may occur via the gluconeogenic pathway, glycolysis is activated at the same time by changes in the phosphorylation state of key regulatory enzymes as well as by the small rise in fructose 2,6-bisphosphate.     

Relationship of lipoamide dehydrogenases from Pseudomonas putida to other FAD-linked dehydrogenases

Pseudomonas putida produces two lipoamide dehydrogenases, LPD-glc and LPD-val. LPD-val is specifically required as the lipoamide dehydrogenase of branched-chain keto acid dehydrogenase and LPD-glc fulfills all other requirements for lipoamide dehydrogenase. Both proteins are dimers with one FAD per subunit. LPD-glc has an absorption maximum at 455 nm, but LPD-val has a maximum at 460 nm. Comparison of amino acid compositions revealed that LPD-glc was more closely related to Escherichia coli and pig heart lipoamide dehydrogenase than to LPD-val. LPD-val did not appear to be closely related to any of the proteins compared with the possible exception of mercuric reductase.     

Phosphorylation of the microtubule-associated protein MAP2 by GTP.

The chick brain microtubule-associated protein MAP2 can be phosphorylated in vitro to the extent of 12 mol/mol with GTP at the same sites as can be labelled by the cyclic AMP-independent protein kinase utilizing [gamma-32P]ATP as the phosphoryl donor. Consequently, the microtubule protein is chemically modified by the conditions usually employed for studies of microtubule assembly, so that the derived kinetic parameters may not relate to steady-state conditions.     

Correlation between serum ionised calcium and serum albumin concentrations in two hospital populations.

One quarter of 172 patients from two hospitals with no obvious disturbances of calcium homeostasis and with total serum calcium concentrations that were normal after adjustment for albumin concentration had low serum ionised calcium concentrations. The low values were not due to changes in pH but were associated with hypoalbuminaemia. Significant positive regressions of ionised calcium on albumin concentration were observed in patients from both hospitals and also in 48 healthy laboratory staff. Because the regressions did not differ between patients and healthy subjects the low ionised calcium values associated with hypoalbuminaemia are unlikely to have been of pathological importance. These findings indicate that interpreting serum ionised calcium concentrations in patients with a reduced serum albumin concentration on the basis of a reference range determined in subjects with a normal serum albumin concentration may be clinically misleading.     

Decrease in ribosomal proteins 1, 2/3, L4, and L7 in Drosophila melanogaster in the absence of X rDNA

Summary The rRNA genes (rDNA) in Drosophila melanogaster are found in two clusters, one on the X and one on the Y chromosome. We have compared the ribosomal protein composition of wild-type Oregon-R flies containing both X-linked and Y-linked rDNA with that of flies containing only the Y-linked rDNA by two-dimensional polyacrylamide gel electrophoresis. Four basic proteins (1, 2/3, L4, and L7) normally present in wild-type flies were either electrophoretically not detectable (1, 2/3, and L4) or marginally detectable (L7) in flies with only Y-linked rDNA. No additional proteins were observed in these flies. However, immunodiffusion assays using specific antibodies raised against purified protein L4 confirmed that L4 was present but in relatively lower amounts in these Y-linked rDNA flies. An investigation was carried out to determine whether these electrophoretically undetectable proteins were more readily lost during ribosome preparation and hence were not readily detectable in the 80S particles by gel electrophoresis or whether they had been modified. Thus the proteins in the post-ribosomal cell supernatant and the high salt sucrose gradient were analyzed by two-dimensional gel electrophoresis and immunochemical assays with antibodies raised against protein L4 and total 80S ribosomal proteins. The experimental evidence indicates that there is a small amount of protein L4 and probably proteins 1, 2/3, and L7 in flies with only Y-linked rDNA but significantly less of these proteins than in wild-type flies.