Leptin, but not immune function, is linked to reproductive responsiveness to photoperiod

Energetic demands are high while energy availability is minimum during winter. To cope with this energetic bottleneck, animals exhibit numerous energy-conserving adaptations during winter, including changes in immune and reproductive functions. A majority of individual rodents within a population inhibits reproductive function (responders) as winter approaches. A substantial proportion of small rodents within a species, however, fails to inhibit reproduction (nonresponders) during winter in the field or in the laboratory when maintained in winter-simulated day lengths. In contrast, immune function is bolstered by short day lengths in some species. The specific mechanisms that link reproductive and immune functions remain unspecified. Leptin is a hormone produced by adipose tissue, and several studies suggest that leptin modulates reproductive and immune functions. The present study sought to determine if photoperiodic alterations in reproductive function and leptin concentrations are linked to photoperiod-modulated changes in immune function. Siberian hamsters (Phodopus sungorus) were housed in either long (LD 16:8) or short (LD 8:16) day lengths for 9 wk. After 9 wk, blood samples were collected during the middle of the light and dark phase to assess leptin concentrations. One week later, animals were injected with keyhole limpet hemocyanin to evaluate humoral immunity. Body mass, body fat content, and serum leptin concentrations were correlated with reproductive responsiveness to photoperiod; short-day animals with regressed gonads exhibited a reduction in these measures, whereas short-day nonresponders resembled long-day animals. In contrast, immune function was influenced by photoperiod but not reproductive status. Taken together, these data suggest that humoral immune function in Siberian hamsters is independent of photoperiod-mediated changes in leptin concentrations.     

Metabolic rate is negatively linked to adult survival but does not explain latitudinal differences in songbirds

Survival rates vary dramatically among species and predictably across latitudes, but causes of this variation are unclear. The rate‐of‐living hypothesis posits that physiological damage from metabolism causes species with faster metabolic rates to exhibit lower survival rates. However, whether increased survival commonly observed in tropical and south temperate latitudes is associated with slower metabolic rate remains unclear. We compared metabolic rates and annual survival rates that we measured across 46 species, and from literature data across 147 species of birds in northern, southern and tropical latitudes. High metabolic rates were associated with lower survival but survival varied substantially among latitudinal regions independent of metabolism. The inability of metabolic rate to explain latitudinal variation in survival suggests (1) species may evolve physiological mechanisms that mitigate physiological damage from cellular metabolism and (2) extrinsic rather than intrinsic sources of mortality are the primary causes of latitudinal differences in survival.     

The effect of cholesterol feeding on gallbladder bile acids of the rabbit. Evidence that lithocholic acid is a primary bile acid in the rabbit.

The bile acid in gallbladder bile of rabbits fed a normal diet or one containing 2% (w/w) cholesterol have been determined by gas chromatography-mass spectrometry. The predominant bile acids in normally fed rabbits were 3 alpha, 7 alpha, 12 alpha-trihydroxy-5 beta-cholan-24-oic acid (cholic acid), 3 alpha, 12 alpha-dihydroxy-5 alpha-cholan-24-oic acid (allodeoxycholic acid) and 3 alpha, 12 alpha-dihydroxy-5 beta-cholan-24-oic acid (deoxycholic acid) with very much smaller amounts of 3 alpha-hydroxy-5 beta-cholan-24-oic acid (lithocholic acid) and 3 alpha, 12 beta-dihydroxy-5 beta-cholan-24-oic acid. In the cholesterol-fed animals the lithocholate became a predominant bile acid. Sulphated bile acids accounted for less than 1% of the total bile acids. It is proposed that lithocholic acid may be a primary bile acid in the cholesterol-fed rabbit, formed by an alternative pathway of biosynthesis involving hepatic mitochondria.     

Cell membrane, but not circulating, carcinoembryonic antigen is linked to a phosphatidylinositol-containing hydrophobic domain

Carcinoembryonic antigen is present in the cell membrane of most tumors of colorectal origin and in the plasma of patients with colorectal cancer and other malignancies. In this paper we demonstrate that carcinoembryonic antigen can be released from HT-29 cells by phosphatidylinositol specific phospholipase C. Triton X-114 phase separation shows that phospholipase C converts the antigen into a water soluble protein. In addition, plasma carcinoembryonic antigen behaves as the cleaved antigen in phase separation experiments. This strongly suggests that carcinoembryonic antigen is attached to cell membranes by a glycosyl-phosphatidylinositol anchor and that it can be released in vivo by enzymatic cleavage of the hydrophobic tail.     

Keratin 13 expression is linked to squamous differentiation in rabbit tracheal epithelial cells and down-regulated by retinoic acid

Rabbit tracheal epithelial (RbTE) cells in primary culture undergo at confluence a multistep program of squamous differentiation. This study examines the expression of keratins in RbTE cells in relation to this differentiation process. During the exponential growth phase RbTE cells are undifferentiated and express three major keratins, K5, K14, and K19, and two minor keratins, K6 and K16. Squamous differentiation is accompanied by increased expression of keratins K6, K16, and K19, and in particular of keratin K13, which reacts specifically with the monoclonal antibody AE8. These changes in keratin synthesis coincide with the commitment to terminal differentiation. Retinoic acid, an inhibitor of the expression of the squamous differentiated phenotype, inhibits the increase in the expression of K6, K16, and K13 and reduces the expression of K5 and K14; however, retinoic acid treatment results in increased levels of keratin K19 and K18. Retinoic acid inhibits the expression of K16 and K13 at concentrations as low as 10(-9)-10(-10) M. At least some of these changes in keratins appear to be related to alterations in the cellular levels of the respective mRNAs. Our results indicate that specific changes in keratin expression, in particular keratin K13, correlate with the onset of squamous differentiation in RbTE cells. Induction of the expression of keratin K13 may function as a marker of squamous differentiation in tracheobronchial epithelial cells.     

Physical activity is linked to ceruloplasmin in the striatum of intact but not MPTP-treated primates

Ceruloplasmin is a protective ferroxidase. Although some studies suggest that plasma ceruloplasmin levels are raised by exercise, the impact of exercise on brain ceruloplasmin is unknown. We have examined whether striatal ceruloplasmin is raised with treadmill exercise and/or is correlated with spontaneous physical activity in rhesus monkeys. Parkinson??s disease is characterized by a loss in ceruloplasmin and, similarly, Parkinson??s models lead to a loss in antioxidant defenses. Exercise might protect against Parkinson??s disease and is known to prevent antioxidant loss in experimental models. We have therefore examined whether treadmill exercise prevents ceruloplasmin loss in monkeys treated unilaterally with the dopaminergic neurotoxin MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine). We found that exercise raised ceruloplasmin expression in the caudate and accumbens but not the putamen of intact monkeys. However, putamen ceruloplasmin was correlated with spontaneous activity in a home pen. MPTP alone did not cause unilateral loss of ceruloplasmin but blocked the impact of exercise on ceruloplasmin. Similarly, the correlation between putamen ceruloplasmin and activity was also lost with MPTP. MPTP elicited loss of tyrosine hydroxylase in the treated hemisphere; the remaining tyrosine hydroxylase was correlated with overall daily activity (spontaneous activity plus that induced by the treadmill). Thus, treadmill activity can raise ceruloplasmin but this impact and the link with spontaneous activity are both diminished in Parkinsonian primates. Furthermore, low overall physical activity predicts greater loss of dopaminergic phenotype in MPTP-treated primates. These data have implications for the maintenance of active lifestyles in both healthy and neurodegenerative conditions.     

Ketocarotenoid circulation,but not retinal carotenoid accumulation,is linked to eye disease status in a wild songbird

Pathogenic or parasitic infections pose numerous physiological challenges to organisms. Carotenoid pigments have often been used as biomarkers of disease state and impact because they integrate multiple aspects of an individual’s condition and nutritional and health state. Some diseases are known to influence carotenoid uptake from food (e.g. coccidiosis) and carotenoid use (e.g. as antioxidants/immunostimulants in the body, or for sexually attractive coloration), but there is relatively little information in animals about how different types of carotenoids from different tissue sources may be affected by disease. Here we tracked carotenoid accumulation in two body pools (retina and plasma) as a function of disease state in free-ranging house finches (Haemorhous mexicanus). House finches in eastern North America can contract mycoplasmal conjunctivitis (Mycoplasma gallisepticum, or MG), which can progress from eye swelling to eye closure and death. Previous work showed that systemic immune challenges in house finches lower carotenoid levels in retina, where they act as photoprotectors and visual filters. We assessed carotenoid levels during the molt period, a time of year when finches uniquely metabolize ketocarotenoids (e.g. 3-hydroxy-echinenone) for acquisition of sexually selected red plumage coloration, and found that males infected with MG circulated significantly lower levels of 3-hydroxy-echinenone, but no other plasma carotenoid types, than birds exhibiting no MG symptoms. This result uncovers a key biochemical mechanism for the documented detrimental effect of MG on plumage redness in H. mexicanus. In contrast, we failed to find a relationship between MG infection status and retinal carotenoid concentrations. Thus, we reveal differential effects of an infectious eye disease on carotenoid types and tissue pools in a wild songbird. At least compared to retinal sources (which appear somewhat more temporally stable than other body carotenoid pools, even to diseases of the eye evidently), our results point to either a high physiological cost of ketocarotenoid synthesis (as is argued in models of sexually selected carotenoid coloration) or high benefit of using this ketocarotenoid to combat infection.     

Arabidopsis TRAPPII is functionally linked to Rab-A,but not Rab-D in polar protein trafficking in trans-Golgi network

The trans-Golgi network (TGN) in plant cells is an independent organelle, displaying rapid association and dissociation with Golgi bodies. In plant cells, the TGN is the site where secretory and endocytic membrane trafficking meet. Cell wall components, signaling molecules and auxin transporters have been found to undergo intracellular trafficking around the TGN. However, how different trafficking pathways are regulated and how different cargoes are sorted in the TGN is poorly defined in plant cells. Using a combined approach of genetic and in vivo imaging, we recently demonstrated that Arabidopsis TRAPPII acts in the TGN and is required for polar targeting of PIN2, but not PIN1, auxin efflux carrier in root tip cells. Here, we report that, TRAPPII in Arabidopsis is required for polar distribution of AUX1, an auxin influx carrier in protophloem cells and epidermal cells of Arabidopsis root tips. In yeast cells, TRAPPII serves as a guanine-nucleotide exchange factor (GEF) for Ypt1 and Ypt31/32 in late Golgi trafficking, while in mammalian cells, TRAPPII acts as a GEF for Rab1 (homolog of yeast Ypt1) in early Golgi trafficking. We show here that TRAPPII in Arabidopsis is functionally linked to Rab-A proteins, homologs of yeast Ypt31/32, but not Rab-D proteins, homologs of yeast Ypt1 and animal Rab1 proteins.     

Sex, but not maternal protein or folic acid intake, determines the fatty acid composition of hepatic phospholipids, but not of triacylglycerol, in adult rats

The aim of the study was to investigate whether the protein and folic acid content of the maternal diet and the sex of the offspring alter the polyunsaturated fatty acid content of hepatic phospholipids and triacylglycerol (TAG). Pregnant rats were fed diets containing 18% or 9% protein with either 1 or 5mg/kg folic acid. Maternal diet did not alter hepatic lipid composition in the adult offspring. Data from each maternal dietary group were combined and reanalysed. The proportion of 18:0, 20:4n-6 and 22:6n-3 in liver phospholipids was higher in females than in males, while hepatic TAG composition did not differ between sexes. Delta5 Desaturase expression was higher in females than in males. Neither Delta5 nor Delta6 desaturase expression was related to polyunsaturated fatty acid concentrations. These results suggest that sex differences in liver phospholipid fatty acid composition may reflect primary differences in the specificity of phospholipid biosynthesis.     

Immunohistochemical analysis of the binding of human IgM to secretory component present in normal adult colon epithelia, but not in colon cancer and fetal colon epithelia

We have analysed the binding of human IgM to fetal, normal adult and malignant colo-rectal tissues. Using an indirect immunoperoxidase technique on sections of frozen tissues human IgM binds to all normal adult colo-rectal epithelia (n = 15) tested. By contrast, 9 out of 25 colo-rectal adenocarcinomas were negative, and in the remaining 16 the staining reaction varied from staining of all the cancer areas to focal staining of a few areas. Human IgM did not bind to 14 samples of fetal intestinal epithelium (gestational age of 6-14 weeks). The binding of IgM was found to be mediated by secretory component (SC) as anti-SC antibody (anti-SC) showed a similar staining pattern as IgM and the IgM binding could be blocked by anti-SC. SC was also demonstrated in glandular epithelia of sections of all normal breast epithelia but only in 10 out of 15 breast adenocarcinomas. The loss of IgM binding and SC could not be correlated to the morphology of the adenocarcinomas. The observations on fetal, normal adult and malignant tissue suggest that IgM binding and SC may be gradually lost during dedifferentiation of normal cells, to malignant colo-rectal or breast epithelia.     

Immunohistochemical analysis of the binding of human IgM to secretory component present in normal adult colon epithelia,but not in colon cancer and fetal colon epithelia

Summary We have analysed the binding of human IgM to fetal, normal adult and malignant colo-rectal tissues. Using an indirect immunoperoxidase technique on sections of frozen tissues human IgM binds to all normal adult colo-rectal epithelia (n=15) tested. By contrast, 9 out of 25 colo-rectal adenocarcinomas were negative, and in the remaining 16 the staining reaction varied from staining of all the cancer areas to focal staining of a few areas. Human IgM did not bind to 14 samples of fetal intestinal epithelium (gestational age of 6–14 weeks). The binding of IgM was found to be mediated by secretory component (SC) as anti-SC antibody (anti-SC) showed a similar staining pattern as IgM and the IgM binding could be blocked by anti-SC. SC was also demonstrated in glandular epithelia of sections of all normal breast epithelia but only in 10 out of 15 breast adenocarcinomas. The loss of IgM binding and SC could not be correlated to the morphology of the adenocarcinomas. The observations on fetal, normal adult and malignant tissue suggest that IgM binding and SC may be gradually lost during dedifferentiation of normal cells, to malignant colo-rectal or breast epithelia.     

The rate of spontaneous epistaxis is not linked to the lunar cycle but shows seasonal variations

Since 50–60% of the human body consists of water, the physiology of blood circulation might be affected by a full moon differently than during other days of the month. This study analyzed a potential association among lunar phases, seasonal variations, and the rate of spontaneous epistaxis. Consecutive admissions solely for spontaneous epistaxis to an otolaryngology emergency room of a single medical center during 1 year were evaluated. The applied tests failed to show changes of admissions during different lunar phases. According to multiple comparisons, admissions were significantly less frequent during the summer months, similar to findings from other countries of the northern hemisphere with varying climates, suggesting an influence of circannual rhythms rather than of environmental conditions.     

The putative signal peptide of glucagon-like peptide-1 receptor is not required for receptor synthesis but promotes receptor expression

GLP-1R (glucagon-like peptide-1 receptor) mediates the ‘incretin effect’ and many other anti-diabetic actions of its cognate ligand, GLP-1 (glucagon-like peptide-1). It belongs to the class B family of GPCRs (G protein-coupled receptors) and possesses an N-terminal putative SP (signal peptide). It has been reported that this sequence is required for the synthesis of GLP-1R and is cleaved after receptor synthesis. In the present study, we conducted an in-depth exploration towards the role of the putative SP in GLP-1R synthesis. A mutant GLP-1R without this sequence was expressed in HEK293 cells (human embryonic kidney 293 cells) and displayed normal functionality with respect to ligand binding and activation of adenylate cyclase. Thus the putative SP does not seem to be required for receptor synthesis. Immunoblotting analysis shows that the amount of GLP-1R synthesized in HEK293 cells is low when the putative SP is absent. This indicates that the role of the sequence is to promote the expression of GLP-1R. Furthermore, epitopes tagged at the N-terminal of GLP-1R are detectable by immunofluorescence and immunoblotting in our experiments. In conclusion, the present study points to different roles of SP in GLP-1R expression which broadens our understanding of the functionality of this putative SP of GLP-1R and possibly other Class B GPCRs.     

Pyrazinamide, but not pyrazinoic acid, is a competitive inhibitor of NADPH binding to Mycobacterium tuberculosis fatty acid synthase I

Pyrazinamide (PZA), an essential component of short-course anti-tuberculosis chemotherapy, was shown by Saturation Transfer Difference (STD) NMR methods to act as a competitive inhibitor of NADPH binding to purified Mycobacterium tuberculosis fatty acid synthase I (FAS I). Both PZA and pyrazinoic acid (POA) reversibly bind to FAS I but at different binding sites. The competitive binding of PZA and NADPH suggests potential FAS I binding sites. POA was not previously known to have any specific binding interactions. The STD NMR of NADPH bound to the mycobacterial FAS I was consistent with the orientation reported in published single crystal X-ray diffraction studies of fungal FAS I. Overall the differences in binding between PZA and POA are consistent with previous recognition of the importance of intracellular accumulation of POA for anti-mycobacterial activity.     

The adolescent decline of NREM delta, an indicator of brain maturation, is linked to age and sex but not to pubertal stage

Two dramatic phenomena of human adolescence are sexual maturation and a steep decline in the delta EEG of non-rapid eye movement (NREM) sleep. It has long been speculated that these developmental changes are causally related. Here, we present the first longitudinal data on this issue. Cohorts of 9- and 12-year-old children (n = 31, 38) were studied with in-home sleep EEG recordings at 6-mo intervals over 2 years. Pubertal (Tanner) stage, height, and weight were obtained at each time point. NREM delta power density (DPD) did not change significantly over ages 9-11 years, and its level did not differ in boys and girls. DPD declined by 25% between ages 12 and 14 years. This decline was parallel in the two sexes, but levels were lower in girls, suggesting that their DPD decline began earlier. Mixed effect analyses demonstrated that DPD was strongly related to age with Tanner stage, height, weight and body mass index controlled but that none of these measures of physical and sexual development was related to DPD with age controlled. NREM delta is the sleep EEG component homeostatically related to prior waking duration and the intensity of waking brain activity. We hypothesize that the DPD decline is caused by age-programmed synaptic pruning that decreases waking brain metabolic rate. This reduced rate would decrease the "substrate" for delta homeostasis. Whether or not this interpretation proves correct, these longitudinal data demonstrate that the delta decline in adolescence reflects brain processes that are not predicted by physical growth or sexual maturation.     

Saturated fatty acids, but not unsaturated fatty acids, induce the expression of cyclooxygenase-2 mediated through Toll-like receptor 4

Results from our previous studies demonstrated that activation of Toll-like receptor 4 (Tlr4), the lipopolysaccharide (LPS) receptor, is sufficient to induce nuclear factor kappaB activation and expression of inducible cyclooxygenase (COX-2) in macrophages. Saturated fatty acids (SFAs) acylated in lipid A moiety of LPS are essential for biological activities of LPS. Thus, we determined whether these fatty acids modulate LPS-induced signaling pathways and COX-2 expression in monocyte/macrophage cells (RAW 264.7). Results show that SFAs, but not unsaturated fatty acids (UFAs), induce nuclear factor kappaB activation and expression of COX-2 and other inflammatory markers. This induction is inhibited by a dominant-negative Tlr4. UFAs inhibit COX-2 expression induced by SFAs, constitutively active Tlr4, or LPS. However, UFAs fail to inhibit COX-2 expression induced by activation of signaling components downstream of Tlr4. Together, these results suggest that both SFA-induced COX-2 expression and its inhibition by UFAs are mediated through a common signaling pathway derived from Tlr4. These results represent a novel mechanism by which fatty acids modulate signaling pathways and target gene expression. Furthermore, these results suggest a possibility that propensity of monocyte/macrophage activation is modulated through Tlr4 by different types of free fatty acids, which in turn can be altered by kinds of dietary fat consumed.     

Cellular retinoic acid-binding protein II gene expression is directly induced by estrogen,but not retinoic acid,in rat uterus

It has been suggested that cellular retinoic acid-binding protein (II) (CRABP(II)) may have a role in the movement of retinoic acid (RA) to its nuclear receptors, thereby enhancing the action of RA in the cells in which it is expressed. RA has also been shown to increase expression of CRABP(II). Previous work from our laboratory has shown that 17 beta-estradiol (E2) administration to prepubertal female rats leads to acquisition of the ability of the lining epithelium to synthesize RA as well as to express CRABP(II). To determine whether this appearance of CRABP(II) was dependent on the production of RA, both E2 and RA were administered to ovariectomized rats. E2 administration induced expression of the CRABP(II) gene in the uterus within 4 h, and this induction was not inhibited by prior administration of puromycin, indicating that the induction was direct. In contrast, RA caused no change in CRABP(II) message level, even at times as late as 48 h after administration. Isolation and analysis of 4.5 kb of the 5'-flanking region of the gene revealed no apparent E2-response element. Using this portion of the gene to drive expression of the luciferase gene in transfected cells allowed identification of a region containing an imperfect estrogen-response element and estrogen-response element half-site, necessary for E2-driven induction. A possible Sp1 binding site in the 5'-flanking region of the CRABP(II) gene was also required for this induction. The ability of E2 to induce expression of CRABP(II) suggests that it can enhance the activity of RA, directly affecting expression of retinoid-responsive genes.