Gene/Protein Disease Symptom Drug Enzyme Compound
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 897 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Two experiments were conducted to determine broiler response to dietary protein during short (1 wk) or prolonged (>3 wk) heat stress (HS). In experiment 1, 21-d-old birds were kept at 20.3 degrees C (thermoneutral; TN), 27.3 degrees C (medium temperature; MT), or 31.4 degrees C (high temperature; HT) and fed diets with 18, 20, 23, or 26% CP for 21 d. Each treatment consisted of 2 blocks of 3 replicates of 15 birds. In experiment 2, broilers were fed diets with 18 or 26% CP or fed ad libitum 2 diets with 10 or 30% CP. Birds were kept at TN (23.5 degrees C) or slowly introduced to HS from 7 to 14 d of age and kept at HT thereafter (chronic; CHS; 29.4 degrees C), and a third group was moved to HT at 21 d (acute HS; AHS; 29.4 degrees C). There were 16 replicates of 4 chickens per treatment distributed in 2 blocks. Performance, body composition, and protein deposition were ascertained from 21 to 28 d and from 28 to 42 d (short and prolonged exposures, respectively). Feeding high protein diets in experiment 1 resulted in linear improvements in body weight gain and feed:gain (P < 0.001) for MT and HT birds, whereas TN birds exhibited a linear (P < 0.001) response to protein. Feed intake declined as CP increased for HT birds during the third week of the study (P < 0.05). In trial 2, better performance was always observed in TN birds. HS depressed performance, although feeding high CP partially ameliorated this effect under AHS and CHS. Regardless of temperature, choice-fed birds selected high protein diets (mean 25.6% CP) and performed similarly to those fed 26% CP. CHS birds showed similar performance to those under AHS. Efficiency of protein deposition was unaffected (P > 0.05). Level of HS and duration of hyperthermia may determine the response of birds to dietary protein. Discrepancies between the 2 studies in response of birds to protein found after prolonged exposure to HS are discussed in view of the differences in levels of certain amino acids used within each experiment.
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PMID:Effects of acute versus chronic heat stress on broiler response to dietary protein. 1633 25

Three-beta-hydroxysteroid dehydrogenase (3beta-HSD) is a key enzyme in the pathway that produces progesterone. Hy-Line hens (W36, W98, and Brown) were subjected to mild heat stress [36 degrees C for 24 h (acute heat stress, AHS) or 2 wk (chronic heat stress, CHS)] or maintained at 22 degrees C (thermoneutral, TN). Granulosa cells (GC) from the 3 largest follicles were isolated, dispersed, and incubated with luteinizing hormone (LH), follicle-stimulating hormone (FSH), prolactin (PRL), a combination, or no hormone (control), and then with pregnenolone nitro blue tetrazolium to determine 3beta-HSD activity. Treatment by LH (TN, P = 0.04; AHS, CHS, P < 0.0001) and by LH+FSH (TN, AHS, CHS, P < 0.0001) resulted in increased enzyme activity compared with the respective controls. In TN and CHS, LH+FSH increased the activity to a greater extent than LH alone (TN, P = 0.02; CHS, P = 0.0004); in AHS the increase was not significant (P = 0.29). Treatment with FSH, PRL, or LH+PRL decreased (TN, AHS) or had no effect (CHS) on 3beta-HSD activity. In TN and AHS cells, FSH and PRL reduced enzyme activity (P = 0.006 and 0.0580, respectively). When LH was added to PRL, suppression by PRL was mitigated somewhat. When LH and FSH were added to PRL, 3beta-HSD activity in AHS and CHS cells actually increased compared with the respective controls (P = 0.052 and 0.003) but remained below the activity of cells incubated with LH+FSH or LH alone. This suggests that gonadotropic actions of LH and LH+FSH are countered by the antigonadotropic action of PRL and, conversely, that PRL reduces the stimulatory action of LH and FSH. Strain differences in GC response to hormones were observed primarily in the CHS-treated birds; generally, W98 was highest; Browns showed the weakest response, and W36 was intermediate. In earlier studies, HS reduced circulating LH and GC progesterone and 3beta-HSD activity in vitro and increased circulating PRL. The results suggest a mechanism by which reduced activity of 3beta-HSD and progesterone by GC during HS might be explained, particularly with the differences in strains observed.
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PMID:Activity of three-beta-hydroxysteroid dehydrogenase in granulosa cells treated in vitro with luteinizing hormone, follicle-stimulating hormone, prolactin, or a combination. 1701 67

The Kibish Formation in southwestern Ethiopia, with an aggregate thickness of approximately 105 m, consists of lacustrine, marginal lacustrine, and deltaic deposits. It is divided into four members numbered I to IV on the basis of erosion surfaces (disconformities) between the strata of each member. It overlies the Mursi and Nkalabong formations, the latter of which is here shown to correlate with the Shungura Formation. Tephra layers in each member allow for secure correlation between geographically separated sections on the basis of the composition of their volcanic glass. Members I, III, and IV of the Kibish Formation appear to have been deposited at the same times as sapropels S7 (197 ka), S4 (104 ka), and S1 (8 ka) in the eastern Mediterranean Sea, respectively. We correlate the KHS Tuff of the Kibish Formation with a >154-kyr-old unnamed tuff in the Konso Formation. Tephra in Member IV may derive from Mount Wenchi, a volcano situated on the divide between the Omo and Blue Nile drainage basins. Thin-bedded sedimentary layers probably represent annual deposition reflecting rapid sedimentation (approximately 30 m/kyr) of parts of the formation. This conclusion is supported by variation in paleomagnetic inclination through a sequence of these layers at KHS. Two fossils of early Homo sapiens (Omo I and Omo II) derive from Member I. Their stratigraphic placement is confirmed by analysis of the KHS Tuff in the lower part of Member II at both fossil sites. The KHS Tuff lies above a disconformity, which itself lies above the fossils at both sites. (40)Ar/(39)Ar dates provide an estimated age of approximately 195 kyr for these fossils. Omo III, a third fossil H. sapiens, probably also derives from Member I of the Kibish Formation and is of similar age. Hominin fossils from AHS, a new site, also derive from Member I. Hominin fossils from CHS can only be placed between 104 ka and 10 ka, the H. sapiens specimen from JHS is most likely 9-13 kyr in age, and a partial skeleton of H. sapiens from Pelvic Corner is most likely approximately 6.6 kyr in age.
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PMID:Stratigraphy and tephra of the Kibish Formation, southwestern Ethiopia. 1869 19