| 1. |
- Azerkan, Leila, et al.
(författare)
-
Characterization of oxyntic glands isolated from the rat gastric mucosa
- 2001
-
Ingår i: Comparative Biochemistry and Physiology A. - 1095-6433 .- 1531-4332. ; 128:2, s. 349-357
-
Tidskriftsartikel (refereegranskat)abstract
- A simple and reproducible method for isolating oxyntic glands from the rat gastric mucosa was developed. The mucosa was incubated with pronase and EGTA, and then treated mechanically to release glands that were separated from single cells by sedimentation. Parietal cells were identified by immunostaining using a monoclonal antibody against H,K-ATPase. The glandular cells appeared morphologically intact. By careful control of the conditions of gland isolation, long glandular structures comprising hundreds of cells surrounding the lumen were obtained. Intraperitoneal injection of Br-deoxyuridine in the rat 1.5 h before the isolation procedure resulted in glands with a labeling of cells in their neck region. The glands were viable, as demonstrated by their ability to respond to various hormones. Histamine dose-dependently stimulated the acid formation which was measured as the accumulation of [14C]aminopyrine. At 100 microM histamine the accumulation was increased 5-10-fold. At 100 nM, pentagastrin potentiated the histamine stimulated accumulation by approximately 40% but pentagastrin alone did not stimulate. The oxyntic glands obtained by the present procedure appear useful for studies on cell physiology, including regulation of acid secretion, cellular interactions, and possibly also differentiation and proliferation mechanisms since long glandular fragments that contained the proliferative zone could be isolated.
|
|
| 2. |
- Bengtsson, Per, et al.
(författare)
-
Effects of cholecystokinin on acid formation in glands and cells isolated from rabbit and rat gastric mucosa
- 2000
-
Ingår i: Comparative Biochemistry and Physiology A. - 1095-6433 .- 1531-4332. ; 126:1, s. 77-84
-
Tidskriftsartikel (refereegranskat)abstract
- Isolated gastric glands and isolated cells prepared from rabbit and rat were studied to analyse the influence of cholecystokinin octapeptide (CCK 8) on histamine stimulated parietal cell acid formation as assessed by [14C]aminopyrine sequestered in acid tissue compartments. In rabbit gastric glands, CCK 8 evoked 32±6% (P<0.01) inhibition of histamine stimulated acid formation, whereas in glands prepared from rat no inhibition was recorded. Instead, CCK 8 seemed to induce a variable increase of the histamine stimulation in rat gastric glands as the aminopyrine accumulation was increased by 110±46% (P<0.1). Further studies on cell preparations derived from rabbit gastric mucosa revealed dual properties of CCK 8, eliciting either inhibition or stimulation of the parietal cell depending on the presence of endocrine cells. The results show that paracrine communication may be effective in glandular preparations, but seems to vary depending on species.
|
|
| 3. |
|
|
| 4. |
- Antonopoulou, Efthimia, et al.
(författare)
-
Effects of aromatase inhibitors and different doses of testosterone on gonadotropins in one year old male Atlantic salmon (Salmo salar).
- 2009
-
Ingår i: Comparative biochemistry and physiology. Part A, Molecular & integrative physiology. - : Elsevier BV. - 1531-4332 .- 1095-6433. ; 153:4, s. 408-16
-
Tidskriftsartikel (refereegranskat)abstract
- The effects of different doses of testosterone (T), the aromatase inhibitors 1,4,6-androstatriene-3,17-dione (ATD) and 4-hydroxy-4-androstene-3,17-dione (4OH), and the combined treatment of T and ATD on luteinizing hormone (LH) and follicle-stimulating hormone (FSH) at the onset of puberty in juvenile Atlantic salmon males were investigated. T always increased pituitary LH. Also, ATD increased pituitary LH, though to a lesser extent than T. However, ATD combined with T diminished pituitary LH levels compared to T alone, indicating an aromatase-dependent positive feedback of T on LH in immature males. 4OH, which was less effective than ATD as an aromatase inhibitor, increased LH content. ATD treatment resulted in increased pituitary FSH levels, similar to those of mature controls. Positive effects of ATD on plasma FSH were found, indicating the presence of an aromatase-dependent negative feedback. The 4OH effects on FSH levels were inconsistent. T exerted both positive and negative effects on pituitary FSH and testes growth, depending on dose and season, with the positive effects being more pronounced with the low doses and the negative effects with the high doses. The treatment of T combined with ATD did not affect the positive effect of T alone on pituitary and plasma FSH, indicating the presence of an aromatase-independent positive feedback on FSH. There was a positive correlation between FSH and gonadosomatic index, especially during summer when gonadal development occurs.
|
|
| 5. |
|
|
| 6. |
- Buddington, RK, et al.
(författare)
-
Absorption of alpha-ketoglutarate by the gastrointestinal tract of pigs
- 2004
-
Ingår i: Comparative Biochemistry and Physiology A. - : Elsevier BV. - 1531-4332. ; 138:2, s. 215-220
-
Tidskriftsartikel (refereegranskat)abstract
- Only a small percentage of alpha-ketoglutarate (AKG) administered lumenally to pigs appears in the portal circulation. This has been attributed to mucosal metabolism, and possibly by limited absorption. Although transporters for di- and tricarboxylic acids, which includes the sodium-dependent transporter NaDC-1, have been detected in the small intestine, correlations with functional assays are lacking. Therefore, intact tissues from three regions of the small intestine, stomach, and colon of weaned pigs were used to measure rates of AKG absorption. Western analysis was used to detect NaDC-1 in the three regions of small intestine. Rates of AKG absorption were highest in the small intestine, lowest in the colon, and intermediate in the stomach. Immunoreactive NaDC-1 was detected in the small intestine and this coincided with a component of AKG absorption that was inhibited by AKG and succinate. In contrast, absorption of AKG was inhibitable by unlabeled AKG, but not succinate, in the stomach, and by neither in the colon. Feeding studies indicated that the amounts of AKG that might be included in practical diets for pigs would not (1) upregulate rates of AKG absorption or (2) exceed estimated capacities of the small intestine to absorb AKG. The present findings indicate that the efficacy of AKG as an alternative metabolic fuel for enterocytes to spare dietary amino acids is not limited by absorption.
|
|
| 7. |
- Burraco, Pablo, et al.
(författare)
-
Telomere length mirrors age structure along a 2200-m altitudinal gradient in a Mediterranean lizard
- 2020
-
Ingår i: Comparative Biochemistry and Physiology A. - : Elsevier BV. - 1095-6433 .- 1531-4332. ; 247
-
Tidskriftsartikel (refereegranskat)abstract
- The timing of organisms' senescence is developmentally programmed but also shaped by the interaction between environmental inputs and life-history traits. In ectotherms, ageing dynamics are still poorly understood even though their body temperature, metabolism, or growth trajectory are very sensitive to environmental changes. Here, we investigated the role of life-history traits such as age, sex, body size, body condition, and tail autotomy (i.e self-amputation) in shaping telomere length in six populations of the Algerian sand lizard (Psammodromus algirus) distributed along an elevational gradient from 300 to 2500 m above the sea level. Additionally, we compiled the available information on reptiles' telomere length in a review table. Our cross-sectional study shows that older lizards have longer telomeres, which might be mostly linked to the selective disappearance of individuals with shorter telomeres or, alternatively, mediated by a higher expression of telomerase across their life. In fact, variation in telomere length across elevation was explained by age structure of lizards; thus, in contrast to our predictions, altitude had no effect on telomere length in this study system. Telomere length was unaffected by tail regeneration and was sex-independent, but positively correlated with body condition, which might be linked to high somatic investment. Hence, our results suggest that life-history traits such as age or body condition can be major drivers of telomere dynamics for this species, whereas environmental conditions apparently had scarce or no effects on lizard telomeres. Our findings emphasize the relevance of understanding species' life histories for fully disentangling the causes and consequences of differences in ageing in ectotherms.
|
|
| 8. |
- Clark, M., et al.
(författare)
-
Revealing the secrets of dormancy and of survival during desiccation
- 2007
-
Ingår i: Comparative Biochemistry and Physiology a-Molecular & Integrative Physiology. - : Elsevier BV. - 1095-6433 .- 1531-4332. ; 146:4
-
Konferensbidrag (refereegranskat)abstract
- Dormancy is a strategy used by many organisms to survive adverse conditions. We aim at enhancing our knowledge of dormancy so as to assess the feasibility of inducing cells or organisms into reversible dormant stages or survival during desiccating conditions. Genomic, proteomic and metabolomic tools used in the course of our studies aim at identifying the molecular and cellular processes that enable five model organisms to tolerate adverse conditions. These are: Cyanobacteria that have specialized dormant cells (akinetes) that tolerate unfavourable environmental conditions Baker's yeast that can survive long periods in a spore phase, that are characterized by desiccation and high levels of trehalose Rotifers that produce eggs (resting eggs) containing developmental-arrested embryos after sexual (but not asexual) reproduction Arctic springtails that reduce their body water content to avoid freezing while producing trehalose and becoming metabolically inactive Killifish embryos in eggs that show resistance to environmental desiccation conditions Our studies aim at revealing the mechanisms that establish dormancy and resistance to desiccation, those that allow the revival from dormant stages and the properties that make dormant stages stress-tolerant. The search for common denominators will assist in leading potentially useful strategies for artificial induction of dormancy and of cell preservation.
|
|
| 9. |
- Dircksen, Heinrich, et al.
(författare)
-
Differential neuronal expression of three Drosophila ion transport peptide splice forms indicate multiple functions of peptidergic neurons
- 2009
-
Ingår i: Comparative Biochemistry and Physiology A. - : Elsevier BV. - 1095-6433 .- 1531-4332. ; 153A:2, suppl. 1, s. S79-
-
Tidskriftsartikel (refereegranskat)abstract
- We identified previously two long (DrmITPL1 and -L2) and one amidated short isoform (DrmITP) of insect ion transport peptides (ITPs) as products derived by alternatively splicing from the Drosophila itp-gene (CG13586). The peptides are members of a large family of arthropod neuropeptides incl. crustacean hyperglycemic hormones (CHH/ITP-family), but similar ITPs are only known in locusts to have antidiuretic bioactivity on the hindgut. We localised the peptides by in situ hybridisation and immunocytochemistry with isoform-specific antibodies in the nervous system of larval (L3) and adult Drosophila melanogaster and screened Gal4-lines specific for peptidergic cells. Four neurosecretory cells in brain-corpora cardiaca/allata putatively release DrmITP as a hormone in all stages. DrmITP also occurs in interneurons in the brain/ventral ganglia and in neurons efferent towards the hindgut. Some interneurons are identical to well-known circadian clock neurons for which the effector molecules were elusive but are responsible for the evening bouts of locomotor activity in flies. DrmITPL1 and -L2 were found only in peripheral lateral bipolar and putative sensory neurons which are likely to play a role in the control of growth, hindgut ion transport and heart beat. With DrmITP identified in brain neurosecretory cells, hindgut-innervating neurons in the abdominal ganglia and one pair in the abdomen close to the larval anal organ or innervating the adult rectal pads, both chloride-transporting organs, we are facing an enormous complexity in multiple functions of differentially expressed ITP/Ls derived from a single gene. Preliminary results using Gal4-driven RNAi in distinct peptidergic neurons look promising to find deficiency phenotypes.
|
|
| 10. |
|
|
