Comparative studies of phosvitin from chicken and salmon egg yolk

• 1.1. A method developed for the isolation of phosvitin from chicken egg yolk was successfully applied to the isolation of phosvitin from salmon eggs.
• 2.2. Salmon roe phosvitin is smaller in molecular size than chicken egg phosvitin.
• 3.3. Circular dichroism spectra of all phosvitins investigated displayed good similarities with spectra showing characteristics of unordered and β-sheet secondary structure.
• 4.4. The main component in the Fourier transform infrared spectra of chicken egg phosvitin is indicative of unordered conformation, whereas the Fourier infrared data of the salmon egg phosvitin are consistent with more of β-sheet structure compared to the chicken egg phosvitin.

     

Immunocytochemical studies of vasotocin and mesotocin in the hypothalamo-hypophysial system of the chicken

Summary The hypothalamo-hypophysial system of the adult chicken has been studied with a monoclonal antibody that cross-reacts with arginine vasotocin and mesotocin. We have used this antibody on thick (100 m) sections in conjunction with a peroxidase-conjugated rabbit antimouse antibody that permits the visualization not only of entire perikarya, but also of long portions of their axons and dendrites. Our results confirm older concepts based on classical methods, but the more sensitive immunocytochemical method reveals that the system is more extensive than previously recognized. Immunostained neurons in the chicken are widely scattered in the hypothalamus. In the rostral preoptic region, there are three immunostained neuronal cell groups: 1) a prominent closely packed group that extends along the ventromedial surface, 2) a diffusely distributed lateral group, and 3) an external group that surrounds the lateral aspect of the septomesencephalic tract. Caudally in the preoptic area and in the anterior hypothalamus, the same groups are present; but there are also conspicuous periventricular perikarya. Many of them have processes that project to the lumen of the third ventricle, as well as parallel axons that arch lateroventrally in the hypothalamus. In the midhypothalamic area, the periventricular perikarya and processes are particularly numerous at the level of the palliai commissure. The dorsal periventricular group located at the level of the dorsomedial anterior nucleus of the thalamus are the most caudal perikarya. They extend laterally in a wing-like formation. The immunostained axons from all of these perikarya form a compact hypothalamo-hypophysial tract as they run from the midhypothalamus to the median eminence and converge beneath the third ventricle. Axons branching from this tract innervate the zone externa of the anterior median eminence; another group of axons running in the fibrous layer of the zona interna proceeds to the neural lobe.     

A potent hypotensive factor in chicken left ventricle

Chicken artria and ventricles both have membrane-bound granules which resemble those containing atriopeptin (ANP) in mammals. However, nothing is known about the contents of the avian granules. A previous study in chickens showed that although extracts of whole chicken heart or synthetic rat ANP both caused profound hypotension, ANP caused both natriuresis and diuresis, while chicken heart extract did not. The present study sought to locate the region(s) of chicken heart containing the hypotensive activity, and to observe the effect on sodium and water excretion and blood pressure in rats. Acid extracts of either atrium, either ventricle, ventricular septum, skeletal muscle, and liver were identically prepared from chickens and rats. Extracts were adjusted to the same protein concentration and injected (0.15 ml/kg) into anesthetized Single Comb White Leghorn roosters. Mean arterial pressure (MAP) and the time for recovery were measured. The most potent extract from chicken hearts was from the left ventricle (-38 +/- 1 mm Hg, 149 +/- 9 sec to recover). All other extracts (including right ventricle) produced only small (10-20 mm Hg), short-lived (20-30 sec) decreases in MAP. In contrast, only rat atrial extracts evoked long-lasting hypotension (greater than 40 mm Hg, recovery time greater than 200 sec). A 30-min infusion of the most potent chicken extract (left ventricle, CLV) into rats produced a small but significant natriuresis and diuresis compared to the vehicle time control (P less than 0.05) and the hypotensive response to bolus injection was about one-third that seen in the chicken. The location of potent spasmolytic activity primarily in chicken left ventricle, the different avian renal responses to chicken heart extract and synthetic rat ANP (5), and the weak diuretic, natriuretic, and hypotensive effects of CLV extract in rats all suggest that the chicken heart substance may be different from mammalian ANP.     

Effects of ectopic pacing on repolarization of the chicken left ventricle

Effects of ectopic pacing on left ventricular repolarization were studied in six anesthetized open-chest chickens. In each animal, unipolar electrograms were acquired from as many as 98 sites with 14 plunge needles (seven transmural locations between epicardium and endocardium in each needle). Activation-recovery intervals (ARIs), corrected to the cycle length, were used for estimating repolarization. At baseline, the nonuniform ARI distribution in the left ventricle resulted in the apicobasal differences being greater than the transmural gradient. Nonuniform ARI prolongation caused by ectopic pacing resulted in decreasing the transmural repolarization gradient and increasing the differences in the apex-to-base direction. The basal, but not apical transmural differences contributed to the total left ventricular transmural gradient. The total left ventricular apicobasal gradient was contributed by the apicobasal differences in mid-myocardial and subendocardial layers more than in subepicardial ones. Thus, in in situ chicken hearts, the transmural and apicobasal ARI gradients exist within the left ventricle with the shortest ARIs in the basal subepicardium and the longest ARIs in the subendocardium of the apical and middle parts of the left ventricle. Apicobasal compared to transmural heterogeneity of local repolarization properties contributes more to the total left ventricular repolarization gradient.     

Immunocytochemical and ultrastructural studies on allografts of the pituitary neurointermediate lobe in the third cerebral ventricle of the rat

Summary Neurointermediate lobes from adult or 10-dayold rats were implanted by a stereotaxic procedure into the third ventricle of adult male rats, in an area close to the paraventricular nucleus. They were examined, using immunocytochemical and ultrastructural techniques, at times ranging from 1 week to 8 months. All grafts were recovered in a healthy condition although some rejection of the tissue was detected at the 1and 2-week stages. In the neural lobe, clusters of pituicytes were scattered among the loose network of capillaries, most of which had a fenestrated endothelium. The intermediate lobe remained organized in compact avascular lobules. Axons similar to those projecting into the neurointermediate lobe in situ, but also axons of other types (e.g., somatostatinergic, enkephalinergic) penetrated the grafts. Synapses with melanotrophic cells in the intermediate lobe and neurohaemal contacts in the neural lobe were frequent from 2 1/2 months after transplantation. Immunocytochemical and ultrastructural characteristics indicated intense secretory stimulation of the melanotrophic cells in the early stages. All cells enclosed in a same glandular lobule reacted in a similar manner. In later stages, when re-innervation occurred, the cells recovered their initial characteristics. The overall effect of the re-innervation of the intermediate lobe grafted in this location is inhibitory, as in the lobe in situ.     

Subcellular localization of dystrophin and vinculin in cardiac muscle fibers and fibers of the conduction system of the chicken ventricle

The subcellular localization of dystrophin and vinculin was investigated in cardiac muscle fibers and fibers of the conduction system of the chicken ventricle by immunofluorescence confocal microscopy. In ventricular cardiac muscle fibers, strong staining with antibody against dystrophin appeared as regularly arranged transverse striations at the sarcolemmal surface, and faint but uniform staining was seen in narrow strips between these striations. In fibers of the ventricular conduction system, the sarcolemma was stained uniformly with this antibody, but strong staining was found as regular striations in many areas and as scattered patches in other areas of the sarcolemma. These intensely stained striations and scattered patches of dystrophin were colocalized with those of vinculin. Because dystrophin striations were located at the level of Z bands of the underlying myofibrils, they were regarded as the concentration of this protein at costameres together with vinculin. In fibers of the conduction system, myofibrils were close to the sarcolemma where dystrophin and vinculin assumed a striated pattern, at some distance from the cell membrane where these proteins exhibited a patchy distribution, and distant from the sarcolemma where dystrophin was uniformly distributed. These data suggest that the distribution patterns of dystrophin reflect the degree of association between the sarcolemma and underlying myofibrils.     

Comparative studies of type X collagen expression in normal and rachitic chicken epiphyseal cartilage

The levels of type X collagen in mineralizing normal chicken epiphyses and nonmineralizing rachitic chicken tibial epiphyses were measured and compared. Qualitative immunoperoxidase studies with anti-chick type X collagen monoclonal antibodies on sections from normal and rachitic cartilage demonstrated that the type X collagen levels in rachitic growth plates are reduced. Northern hybridization of mRNA and biosynthetic studies have confirmed that type X collagen synthesis in rickets is also decreased. In hypocalcemic rickets, the level of type X collagen mRNA is reduced by 80% whereas the level of type X collagen mRNA is only reduced by 50% in normocalcemic rickets. These observations provide additional evidence that type X collagen is involved in the process of cartilage mineralization and also suggest that the partial recovery of type X collagen synthesis in normocalcemic rickets may be related to the elevated plasma concentration of calcium. Calcium concentration may therefore play an important role in the control of type X collagen synthesis.     

Comparative stereology of the mouse and finch left ventricle

The volume fractions and surface per unit cell volume of some subcellular components of the left ventricles of the finch and mouse were quantitated by stereologic techniques. These species were chosen for study because they have similar heart rates but differ morphologically in some respects: fiber diameter is larger in the mouse; the mouse has transverse tubules while the finch does not; and the finch has a form of junctional sarcoplasmic reticulum (JSR), extended JSR (EJSR), located in the cell interior with no direct plasmalemmal contact, while the mouse interior JSR (IJSR) abuts on transverse tubules. Our data show that the volume fraction (V_v) and surface area per unit cell volume (S_v) of total SR, and free SR (FSR) are similar. The volume fractions of mitochondria, myofibrils, and total junctional SR were also similar. The S_v of the cell surface of the finch was similar to the S_v of the cell surface of the mouse (S_v-plasmalemma plus S_v of the transverse tubules). The principal difference was in the distribution of JSR; the mouse peripheral JSR (PJSR) represents only 9% of the total JSR, while the finch PJSR accounts for 24% of the bird's JSR. The similar volume fractions of total junctional SR (PJSR + EJSR in the finch; PJSR + IJSR in the mouse) suggest that the EJSR is not an embryologic remnant, and raises the possibility that some function of JSR is independent of plasmalemmal contact.     

Cholinomimetic teratogens: studies with chicken embryos.

The cholinomimetic compounds carbachol, decamethonium, neostigmine, succinylcholine, trimethylphenylammonium, and others were tested for their interference with normal chick development. All these compounds led to abnormalities of the cervical vertebrae; at higher dosage interference with normal morphogenesis involved the whole vertebral column. Hypoplasia of the leg muscles occurred with lower incidence. Responses, tested with carbachol, rose from 24 to 72 and 96 h, then declined to 120 h of incubation. Two of the cholinometic compounds used in combined treatment produced a high degree of synergism. Gallamine, benzoquinomium, butyrylcholine, and bethanechol had protective effects. Acetylcholine, at high dosage, caused defects different from the above. It is suggested that the cholinomimetic teratogens interfere with normal development by displacing acetylcholine from its receptors or by forming complexes with it.     

Comparative studies of the vascular system of node-leaf continuum in woody ranales

The vascularization of the node-leaf continuum in the first to eighth foliage leaves of the first-year plant ofMagnolia virginiana is investigated. The cotyledonary node is a 4-trace, 3-lacunar type. Vascularization in the cotyledonary node is fundamentally different from that in the folair node of the same plant. As a result, the cotyledonary vascularization is only described but not compared to that in the foliar node-leaf continuum. Considerable diversity occurs in the node-leaf vascularization of the first-year plants. A 5-trace, 4-lacunar vascular system is constant in the lower folair nodes; this is considered to be the fundamental vascular pattern in the node-leaf continuum of the species. In contrast, the nodal anatomy and petiolar vascularization fluctuate widely in the third to eighth leaves of the first-year plants. Variation is found not only between different nodes of a single plant but even in the corresponding nodes of different individuals. The evidence clearly indicates that variation always correlates with certain members of the leaf-trace complement; thus, either the ventral and/or marginal lateral bundles undergo phylogenetical reduction or amplification.     

Comparative studies of the phytochrome system in cell cultures from different plants

Phytochrome contents have been assayed in vivo in cell suspension cultures of Petroselinum hortense, Daucus carota and Glycine max. After transferring the cells to fresh medium phytochrome increased in parallel with the increase in cell number, whereas the amount of phytochrome per cell remained constant. The rate of phytochrome reaccumulation after pretreatment with 15 h red light was very similar in all three systems (2.8–3.6 (e) 10^–5/h). Dark reversion and a fast and slow P_fr destruction were observed in all systems. The rate constants of these reactions varied strongly between the systems. The phytochrome systems of the cell cultures were compared with those of etiolated and light-grown seedlings and it was concluded that the cell suspension cultures of Petroselinum hortense and Daucus carota behaved similarly to light-grown seedlings. In contrast, those of Glycine max behaved similarly to a dark grown seedling.Abbreviations P_r'fr red, far-red absorbing forms of phytochrome - P_tot P_r+P_fr total amount of phytochrome - fwt fresh weight     

Mixing and modes of mass transfer in the third cerebral ventricle: a computational analysis

Anatomic, velocimetric, and brain motion MRI scans were combined with a computational fluid dynamics model to investigate cerebrospinal fluid (CSF) mixing in the third cerebral ventricle of a healthy male adult. It was found that advection dominates over diffusion in most of the third ventricle. Three zones where diffusion plays an important role in the mixing process were identified. One of these zones, consisting of recessus infundibulus, recessus opticus and the adjacent regions up to commissura anterior, is likely to exist in the general population. We hypothesize that this zone may act as a buffer to flatten concentration peaks of pituitary gland hormones released into the CSF of the third ventricle. We further hypothesize that this zone may facilitate the communication between hypothalamus and the pituitary gland through the third ventricle cerebrospinal fluid by prolonging residence times of the communicated hormones.