Correlation of neuronal size and peptide immunoreactivity in the guinea-pig trigeminal ganglion

Summary Frequency and size of guinea-pig trigeminal neurones immunoreactive with antisera to -neo-endorphin(-neo-END), dynorphin A-(DYN), vasoactive intestinal polypeptide-(VIP), somatostatin-(SOM), and substance P-(SP) are reported. Co-localisation of the various peptides to the same ganglion cells was investigated immunocytochemically in consecutive 7-m thick paraffin sections. According to their size, all peptide-immunoreactive neurones belong to the class of small ganglion cells. Within this cell group, SP-immunoreactive neurones appear to be the largest, followed by SOM-, VIP-, -neo-END- and DYN-immunoreactive ganglion cells. The observed differences in size are statistically significant with the exception of that between -neo-END and DYN. This finding correlates well with the observed co-occurrence of the two immunoreactive peptides. All -neo-END-immunoreactive perikarya are also reactive to VIP antisera. These neurones are significantly smaller than those containing VIP-immunoreactivity exclusively. Ganglion cells displaying co-existence of -neoEND- and SP-immunoreactivity or VIP- and SP-immunoreactivity are found too infrequently to allow morphometric analysis. Some non-immunoreactive ganglion cells are shown to be approached by dense baskets of VIP-, -neo-END- or SP-immunoreactive varicose fibres, indicating the presence of intraganglionic modulation sites. The combination of immunohistochemistry and morphometry presented in this study allows the differentiation of diverse populations of primary afferent neurones exhibiting peptide immunoreactivity, most likely reflecting their involvement in different central and peripheral reflex arcs and sensory modalities.     

Effects of secretin and gastric inhibitory polypeptide on human pancreatic growth hormone-releasing factor(1-40)-stimulated growth hormone levels in the rat

Synthetic human pancreatic growth hormone-releasing factor containing 40 amino acids ([hpGRF (1-40)]-OH) significantly stimulated plasma growth hormone (GH) levels in both sodium pentobarbital and urethane anesthetized rats. Synthetic secretin, gastric inhibitory polypeptide (GIP), and glucagon significantly decreased plasma GH levels while synthetic vasoactive intestinal peptide (VIP) had no effect. Secretin and GIP also altered the in vivo plasma GH response to [hpGRF(1-40)]-OH. Whether this effect is the result of an interaction at the pituitary level or is due to an extra-pituitary effect of secretin and GIP awaits further study.     

Purification and characterization of maize ribulose-1,5-bisphosphate carboxylase

The ribulose-1,5-bisphosphate carboxylase/oxygenase purified from maize (a C₄ monocot) to homogeneity has a MW of532 000 and sedimentation coeffici     

Dose-response comparisons of canine plasma gastroenteropancreatic hormone responses to bombesin and the porcine gastrin-releasing peptide (GRP)

This study compares the potencies of the porcine gastrin-releasing peptide (pGRP) and bombesin, in causing elevations of canine plasma gastroenteropancreatic (GEP) levels. In the dose range 0-600 pmol . kg-1 . h-1, infusion of both peptides resulted in obvious dose-related elevations of plasma levels of gastrin, pancreatic polypeptide, enteroglucagon, immunoreactive pancreatic glucagon, and insulin. In this dose range, no significant difference in potency between the two peptides in elevating plasma levels of the above hormones was observed. The results of this study, demonstrating equimolar potency of pGRP and bombesin, are in contrast to previous studies reporting that pGRP was less potent than bombesin in causing certain bioactivities in the rat following intracranial administration of the two peptides.     

Direct and indirect evidence for polypeptide absorption by the teleost gastrointestinal tract

The ability of the gastrointestinal tract of chinook salmon, Oncorhynchus tshawytscha , to absorb polypeptides in vivo was investigated by reference to the appearance of orally administered adrenocorticotropic hormone (ACTH) within the blood of fish previously treated with dexamethasone (3μg g^−l body weight) in order to suppress endogenous ACTH secretion. Further, since cortisol presence within plasma is dependent upon the availability of ACTH, dexamethasone blockade of endogenous ACTH secretion, in conjunction with subsequent measurements of plasma cortisol levels, provides a means by which biological patency of absorbed exogenous ACTH may be demonstrated. Levels of ACTH and cortisol in plasma of dexamethasone-treated salmon were therefore measured for a period of 360 min immediately following oral intubation of ACTH (15μg g⁻¹ body weight). Peak plasma presence of ACTH-like immunoreactivity (676.6 ± 33.6 pg ml⁻¹ plasma) and cortisol (227.1 ± 29.0 ng ml⁻¹ plasma) were recorded 120 min after ACTH administration. Results from the experimental groups were compared to those of 15 control treatments. Since administration of ACTH to chinook salmon elicited a consistent and significant elevation in not only plasma ACTH but also cortisol presence, it is contended that the salmonid gut expresses an ability to absorb polypeptides of dietary origin. The significance of these findings with respect to the oral administration of biologically active peptides and proteins to fish of importance to aquaculture is discussed.     

Early degradation of photosynthetic membranes in carob and sunflower cotyledons

The assimilatory activity of cotyledons can play an essential role in the survival of seedlings with a slow and delayed development of primary leaves. Changes in the photosynthetic activity of the cotyledon, from the onset of greening through senescence, were studied in two such plants, carob and sunflower, in order to determine its efficiency and duration, also in connection with the achievement of assimilatory autonomy by the plantlet. Chlorophyll analyses showed that the cotyledon's chloroplasts reached maximal greening in plantlets with a pair of expanded leaves. In contrast, the cotyledon's photosynthetic activity, measured as the rate of oxygen release, started to decrease early, before expansion of primary leaves. The decrease was due to the inactivation of a number of photosystem II (PSII) units, as revealed by immunodetection of breackdown products of the reaction centre's D1 and D2 thylakoid proteins. No signals of PSII alteration were noticed in the primary leaf chloroplasts that differentiated under the same environmental conditions. The damage to the cotyledon PSII, occurring in a non-photoinhibitory situation, might be due to a slower rate of turnover of D1 polypeptide than in the leaf thylakoids. The differential turnover of this protein in cotyledons and in leaves might represent an organ-specific regulation of the photosynthetic activity. The peculiarity of the cotyledon thylakoids make these organs useful objects for studying the metabolic cycle of both D1 and D2 proteins in vivo, under non-photoinhibiting conditions.     

Colocalization of NADPH-diaphorase activity and certain neuropeptides in the esophagus of opossum (Didelphis virginiana)

Nitric oxide and various neuropeptides in the myenteric plexus regulate esophageal motility. We sought colocalization of nitric oxide synthase and neuropeptides in frozen sections of mid-portion of smoothmuscled opossum esophagus using NADPH-diaphorase activity to mark the synthase and immunoreactivity to detect peptides. The peptides, all with demonstrated physiological activity in this organ, were calcitonin generelated peptide, galanin, neuropeptide Y, substance P, and vasoactive intestinal polypeptide. The ExtrAvidin Peroxidase immunostain for each peptide was carried up to the final peroxidase reaction with 3-amino-9-ethylcarbazole. The NADPH-diaphorase reaction was applied with short incubation to provide light staining just before the peroxidase reaction was performed. We examined sections for the proportions of singly and dually labeled nerve cells in the myenteric plexus. NADPH-diaphorase activity was highly colocalized with calcitonin gene-related peptide (59%), galanin (54%), and vasoactive intestinal polypeptide (53%). It showed little colocalization with neuropeptide Y (10%) and substance P (8%). The proportions of all nerve cells containing each of the substances were: NADPH-diaphorase-33%, calcitonin gene-related peptide-30%, galanin-55%, neuropeptide Y-16%, substance P-35%, and vasoactive intestinal polypeptide-58%. We conclude that the nerves responsible for peristalsis in the esophagus may act by releasing nitric oxide along with other inhibitory substances, calcitonin gene-related peptide, galanin, and vasoactive intestinal polypeptide, but not excitatory substances, neuropeptide Y and substance P.     

Distribution of PACAP (pituitary adenylate cyclase-activating polypeptide)-like and helospectin-like peptides in the teleost gut

Pituitary adenylate cyclase-activating polypeptide (PACAP) and helospectin are two vasoactive intestinal polypeptide (VIP)-related neuropeptides that have recently been demonstrated in the mammalian gut; the aim of this study was to reveal their occurrence and localisation in the gastrointestinal tract, swimbladder, urinary bladder and the vagal innervation of the gut of teleosts, using immunohistochemical methods on whole-mounts and sections of these tissues from the Atlantic cod, Gadus morhua and the rainbow trout, Oncorhynchus mykiss. Both PACAP-like and helospectin-like peptides were present in the gut wall of the two species. Immunoreactive nerve fibres were found in all layers but were most frequent in the myenteric plexus and along the circular muscle fibres. Immunoreactivity was also demonstrated in nerves innervating the swimbladder wall, the urinary bladder and blood vessels to the gut. Immunoreactive nerve cell bodies were found in the myenteric plexus of the gut and in the muscularis mucosae of the swimbladder. In the vagus nerve, non-immunoreactive nerve cells were surrounded by PACAP-immunoreactive fibres. Double staining revealed the coexistence of PACAP-like and helospectin-like peptides with VIP in all visualized nerve fibres and in some endocrine cells. It is concluded that PACAP-like and helospectin-like peptides coexist with VIP in nerves innervating the gut of two teleost species. The distribution suggests that both PACAP and helospectin, like VIP, are involved in the control of gut motility and secretion.     

The use of constitutive nuclear oncoproteins to count neurons in the enteric nervous system of the guinea pig

Immunohistochemical double labelling of the enteric nervous system of the guinea pig ileum was performed with a monoclonal antibody (anti-MYC 033) directed against a peptide sequence of the human c-Myc protein together with antibodies directed against either the neuron-specific antigens neuron-specific enolase or PGP 9.5 or the glia-specific marker S-100 to demonstrate that anti-MYC 033 labelled the nuclei of all enteric neurons but not glia. This strategy was also employed to demonstrate that another anti-c-Myc monoclonal anti-body, anti-MYC 070, labelled the nuclei of all neurons and glia, as well as perhaps all other cells in these preparations. A polyclonal antiserum raised against a peptide sequence of the human c-Fos protein (anti-FOS 4) was shown to label the identical nuclei as anti-MYC 033. The ganglionic density of nuclei labelled by anti-FOS 4 was found to be similar to previous measures of the ganglionic density of neurons. Double labelling with anti-MYC 033 and an antiserum directed against vasoactive intestinal polypeptide was performed to reexamine the ganglionic density of neurons that express this neuropeptide. Our results suggest that the ganglionic density of these neurons might be less than previously determined.     

The legumin gene family: a reconstructed Vicia faba legumin gene encoding a high-molecular-weight subunit is related to type B genes

Nucleotide sequence information from a partial genomic clone, a cDNA clone, a RACE clone and a PCR fragment was combined to reconstruct the first reported complete gene sequence encoding a large legumin subunit, designated LelB3. The length difference to the well-characterized major legumin subunits is caused by an extended glutamin/glutamic acid-rich region encoded by the C-terminal part of the chain. Amino acid sequence comparisons reveal that gene LelB3 is more closely related to B-type than to A-type legumin genes of Vicia faba. Gene LelB3 is a member of a small gene family as indicated by published (Pich and Schubert, Biol Zbl 112 (1993); 342–350) and limited own data.