| 1. |
- Krönström, Jenny, 1978, et al.
(author)
-
Serotonin and nitric oxide interaction in the control of bioluminescence in northern krill, Meganyctiphanes norvegica (M. Sars)
- 2007
-
In: Journal of Experimental Biology. - : The Company of Biologists. - 0022-0949 .- 1477-9145. ; 210:18, s. 3179-3187
-
Journal article (peer-reviewed)abstract
- The role of nitric oxide (NO) in the control of bioluminescence (light production) in the crustacean Meganyctiphanes norvegica (krill) was investigated using pharmacological and immunohistochemical methods. All nitrergic drugs tested failed to induce bioluminescence per se but modulated light production stimulated by 5-hydroxytryptamine (5-HT). NO donors [sodium nitroprusside (SNP) and S-nitroso-N-acetylpenicillamine (SNAP)] injected in live specimens significantly reduced light production stimulated by 5-HT, whereas inhibition of the enzyme NO synthase (NOS) with L-NAME (NG-nitro-L-arginine methyl ester) resulted in an enhancement of the 5-HT response. The effects of NO do not seem to be mediated via production of cGMP as injections of a cGMP analogue (8-Bromoguanosine 3',5'-cyclic monophosphate) gave inconclusive effects on the 5-HT-stimulated light response. Inhibition of cGMP production with ODQ (1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one) did not affect the light response. Moreover, a few individuals showed a considerably higher response to 5-HT in April and June compared with specimens collected in the autumn and winter. Furthermore, both NOS-like and 5-HT-like materials were detected by immunohistochemistry inside the light organs. NOS-like immunoreactivity was primarily observed in structures associated with vessels inside the light organs, whereas 5-HT-like material was abundant in nerve fibres throughout the whole light organ. The results suggest that NO has a modulatory role at several levels in the control of light production in M. norvegica and that NO and 5-HT interact in this regulation.
|
|
| 2. |
|
|
| 3. |
- Claes, Julien, et al.
(author)
-
Nitric oxide in the control of luminescence from lantern shark (Etmopterus spinax)
- 2010
-
In: JOURNAL OF EXPERIMENTAL BIOLOGY. - : The Company of Biologists. - 0022-0949 .- 1477-9145. ; 213:17, s. 3005-3011
-
Journal article (peer-reviewed)abstract
- Abstract: Photophores (photogenic organs) of the lantern shark Etmopterus spinax are under hormonal control, with prolactin (PRL) and melatonin (MT) triggering the light emission. Differential sensitivity to these hormones in adult individuals suggests, however, that the luminescence of this shark is controlled by an additional mechanism. In this study, different techniques were used to investigate a potential modulator of E. spinax luminescence-nitric oxide (NO). NO synthase (NOS)-like immunoreactivity (IR) was found in the photocytes (photogenic cells) of the photophores. In addition, acetylated tubulin IR also supported the presence of nerves running through the photogenic tissue and innervating different structural elements of the photophores: photocytes, pigmented cells from the iris-like structure and lens cells. Pharmacological experiments confirmed a modulatory action of NO on the hormonally induced luminescence: NO donors sodium nitroprusside (SNP) and hydroxylamine decreased the time to reach the maximum amplitude (TLmax) of MT-induced luminescence while these substances decreased the maximum amplitude of PRL-induced luminescence (and also the TLmax in the case of SNP). The small impact of the NOS inhibitor L-NAME on hormonally induced luminescence suggests that NO is only produced on demand. The cGMP analogue 8BrcGMP mimicked the effects of NO donors suggesting that the effects of NO are mediated by cGMP.
|
|
| 4. |
- Cramp, R.L., et al.
(author)
-
The effects of saltwater acclimation on neurotransmitters in the lingual salt glands of the estuarine crocodile, Crocodylus porosus
- 2007
-
In: Regulatory Peptides. - : Elsevier BV. - 0167-0115. ; 140:1-2, s. 55-64
-
Journal article (peer-reviewed)abstract
- Introduction Most avian and reptilian salt glands display marked phenotypic plasticity when animals are exposed to hyperosmotic conditions. In addition, the activity of most salt glands is under considerable control by the nervous system and nerves containing cholinergic, adrenergic and peptidergic neurotransmitters have been identified in avian and reptilian salt gland tissues. The present study sought to determine whether the salt glands of the estuarine crocodile, Crocodylus porosus contain the peptidergic neurotransmitters SP, CGRP, VIP, and PACAP and the gaseous neurotransmitter, NO. In addition, we sought to determine whether there was any evidence for the adaptation of the C. porosus salt gland nervous system to hyperosmotic conditions. Methods Salt glands from freshwater- and saltwater-acclimated C. porosus hatchlings were sectioned and examined immunohistochemically for neurotransmitters within the tissue. Results Neurons containing SP, CGRP, VIP, PACAP and NO synthase were identified within C. porosus salt glands. There was no difference in the overall number (density) of neurons within SW-acclimated tissues when compared with FW-acclimated animals. However, there was a significant reduction in density of neurons containing SP and PACAP in SW-acclimated animals. Conclusion C. porosus salt glands display phenotypic plasticity following exposure to hyperosmotic conditions. In addition to cholinergic and adrenergic neurons, they contain a variety of peptidergic neurotransmitters and the gaseous neurotransmitter NO. Additionally, there appears to be some evidence of acclimation of the nervous system of C. porosus to hypersaline conditions, although the functional significance of these changes remains to be determined.
|
|
| 5. |
|
|
| 6. |
- Holmberg, Anna, 1974, et al.
(author)
-
Enteric Control
- 2007
-
In: Fish Larval Physiology, Eds RN Finn and BG Kapoor. - Enfield, NH, USA : Science Publishers. - 9781578083886 ; , s. 553-572
-
Book chapter (other academic/artistic)
|
|
| 7. |
- Holmberg, Anna, 1974, et al.
(author)
-
Ontogeny of the gut motility control system in zebrafish Danio rerio embryos and larvae
- 2004
-
In: Journal of Experimental Biology. - : The Company of Biologists. - 0022-0949 .- 1477-9145. ; 207:23, s. 4085-4094
-
Journal article (peer-reviewed)abstract
- Using digital motion analysis, the ontogeny of the cholinergic, tachykinin and pituitary adenylate cyclase-activating polypeptide (PACAP) control systems was studied in zebrafish Danio rerio larvae, in vivo. For the first time we show that the regular propagating anterograde waves that occur in the zebrafish larval gut before and around the onset [at 5-6 days post fertilization (d.p.f.)] of feeding are modulated by acetylcholine or atropine, PACAP and NKA (neurokinin A). At 3 d.p.f., when no spontaneous motility has developed, application of acetylcholine did not affect the gut. However, at 4 d.p.f., acetylcholine increased and atropine reduced the frequency of propagating anterograde waves. At 5 d.p.f., NKA increased and PACAP reduced the wave frequency. This suggests that both excitatory and inhibitory pathways develop at an early stage in the gut, independent of exogenous feeding. Immunohistochemistry established the presence of gut neurons expressing PACAP and NKA in the proximal part of the developing gut from the first stage investigated (2 d.p.f.) and before regular motility was observed. I d.p.f. (PACAP) or 2 d.p.f. (NKA) stages later the whole gut was innervated. This supports physiological results that gut motility is under neuronal control during the period when regular motility patterns develop.
|
|
| 8. |
- Holmberg, Anna, 1974, et al.
(author)
-
The effects of endogenous and exogenous nitric oxide on gut motility in zebrafish Danio rerio embryos and larvae
- 2006
-
In: Journal of Experimental Biology. - : The Company of Biologists. - 0022-0949 .- 1477-9145. ; 209:13, s. 2472-2479
-
Journal article (peer-reviewed)abstract
- Using motion analysis, the ontogeny of the nitrergic control system in the gut was studied in vivo in zebrafish Danio rerio embryos and larvae. For the first time we show the presence of a nitrergic tonus, modulating both anterograde and retrograde contraction waves in the intestine of developing zebrafish. At 4 d.p.f. (days post fertilisation), the nitric oxide synthase (NOS) inhibitor L-NAME (three boluses of 50-100 nl, 10(-3) mol l(-1)) increased the anterograde contraction wave frequency by 0.50 +/- 0.10 cycles min(-1). Subsequent application of the NO donor sodium nitroprusside (SNP; three boluses of 50-100 nl, 10(-4) mol l(-1)) reduced the frequency of propagating anterograde waves (-0.71 +/- 0.20 cycles min(-1)). This coincided with the first appearance of an excitatory cholinergic tonus, observed in an earlier study. One day later, at 5 d.p.f., in addition to the effect on anterograde contraction waves, application of L-NAME increased (0.39 +/- 0.15 cycles min(-1)) and following SNP application reduced (-1.61 +/- 0.36 cycles min(-1)) the retrograde contraction wave frequency. In contrast, at 3 d.p.f., when no spontaneous motility is observed, application of L-NAME did not induce contraction waves in either part of the gut, indicating the lack of a functional inhibitory tonus at this early stage. Gut neurons expressing NOS-like immunoreactivity were present in the distal and middle intestine as early as 2 d.p.f., and at 1 day later in the proximal intestine. In conclusion, the present study suggests that a nitrergic inhibitory tonus develops shortly before or at the time for onset of exogenous feeding.
|
|
| 9. |
|
|
| 10. |
|
|
