The fine structure of peritrophic membranes of the blowfly, Calliphora erythrocephala, grown in vitro under different conditions.

The formation of peritrophic membranes (PM) in vitro was studied in a flow chamber in order to avoid the accumulation of metabolic substances during prolonged incubation. During the first 8 to 10 hr of incubation the production of PM was nearly constant—3·5 ± 1·4 mm PM/hr. After about 10 hr it decreased and stopped after about 35 hr. Between 1 and 8 hr after the beginning of incubation the width of the periodic crossband pattern reached or nearly reached the values found in PM which had formed in vivo; afterwards it decreased more and more. During the first 20 min of incubation a ‘disturbed zone’ of PM without any regular crossband pattern is formed.In the cardia of adult Calliphora erythrocephala there are three formation zones forming three PM of different fine structures. The fine structure of PM 1 to 3 formed in vitro during the first 6 to 8 hr of incubation in Leloup's medium 1, with an osmolarity of 340 mOsmol, a pH of 6·8, and a temperature of 27°C, does not differ from the PM grown in vivo. PM 1–3 grown in vitro in Tyrode's solution with added glutamine or in Leloup's medium with added β-ecdysone show a considerable increase in thickness and a disturbed formation of the electron dense layer of PM 1.     

Properties and metabolism of 2alkylalkanoates. 3. absorption of methyl and ethyl 2-methylpalmitate

The recovery from rat and rabbit tissues of fed methyl-(14)C and ethyl-2-(14)C 2-methylpalmitate with unaltered specific activity has demonstrated the existence of mechanisms for the absorption and deposition of both methyl and ethyl esters of fatty acids, at least for 2-methylpalmitate. In thoracic duct-cannulated rats, approximately 9% of the fed compounds was recovered from the lymph during the first 24 hr, the rate of recovery reaching a maximum between 6 and 8 hr. In the rabbit, the fed, unaltered esters in plasma were transported principally by means of the low density lipoproteins. Only trace amounts of the unaltered esters were subsequently detected in the blood and tissue lipids after feeding, however, even during the period of maximal absorption; moreover, in contrast to at least one report by others, further analyses for methyl or ethyl esters of other fatty acids has shown that such esters of short-chain alcohols constitute no more than a trace amount (0.004-1.03%) of the lipids extracted from a wide variety of mammalian tissues. The possibility remains that even these trace amounts of esters arose as artifacts of autolysis, extraction, or assay.     

Perinatal changes in amino acid metabolism of rat brain,especially alanine and glutamic acid

The changes in both the levels of some free amino acids and their metabolism in the rat brain during the first 24 hr of postnatal life were studied. The content of glutamic acid decreased for the first 2 hr; it remained at the lowest level for the next 4 hr, when it began to increase. The content of alanine decreased for the first 6 hr and approached the adult level. Oxygen consumption, glucose oxidation, and pyruvate formation in the cerebral slices of the 24-hr-old rats were as much as 150% of that of the 19-day-old fetus. The distribution profile of radioactivity incorporated into the cerebral amino acids from the subarachnoid-injected [U¹⁴C]glucose was also changed. In the 2- and 6-hr-old rats, 50% of the total radio-activity recovered in the free amino acids was in alanine. Its rate decreased to 30% in the 24-hr-old and was 2% in the adult, while the radioactivity incorporated into glutamic acid increased. Alanine aminotransferase activity started to increase at birth and had the highest level at 24 hr after birth. It then decreased and finally reached the same level as shown at birth. However, aspartate aminotransferase increased during the first 6 hr after birth and did not change until the end of the first day of life.     

Plasma levels of 16 alpha-hydroxypregnenolone, 16 alpha-hydroxyprogesterone and 16 alpha-hydroxydehydroepiandrosterone in the fetus and neonates.

Simultaneous determination of unconjugated 16 alpha-hydroxypregnenolone (16 alphaOH-Preg), 16 alpha-hydroxyprogesterone (16 alphaOH-Prog) and 16 alpha-hydroxydehydroepiandrosterone (16 alphaOH-DHEA) in fetal and neonatal plasma was performed utilizing a newly developed radioimmunoassay. In all neonates, the three 16 alpha-hydroxysteroid levels were consistently higher in umbilical cord plasma than in the maternal peripheral circulation. 16 alpha-OH-Preg in the umbilical arterial plasma increased from 11.2 +/- 3.1 at 24 weeks to 29.7 +/- 12.0 ng/ml at term, 16 alphaOH-Prog from 15.5 +/- 3.2 to 34.3 +/- 11.0 ng/ml and 16 alphaOH-DHEA from 5.1 +/- 1.2 to 5.9 +/- 1.0 ng/ml. In the anencephalic neonates, only 16 alphaOH-Preg showed an increase pattern under ACTH priming. 16 alpha-OH-Preg levels for normal full term neonates remain relatively constant at the first 24 hr and show a slight decrease at 3 days post partum. In small full term neonates, 16 alphaOH-Preg levels in umbilical arterial plasma are considerably higher than in normal neonates and remain at roughly equivalent levels for the first 5 days post partum. 16 alphaOH-Prog and 16 alphaOH-DHEA levels in umbilical arterial plasma in normal and small full term neonates are almost equal and both groups show a rapid decrease during the first 24 hr. Comparison with findings of the three 16 alpha-hydroxysteroids in fetal and neonatal plasma is discussed.     

THE SYNTHESES OF TOTAL MACRONUCLEAR PROTEIN, HISTONE, AND DNA DURING THE CELL CYCLE IN EUPLOTES EURYSTOMUS

Increased alkaline phosphatase activity is induced in certain epithelial cell cultures by hormones with adrenal glucocorticoid activity or their analogues such as prednisolone (Δ^I-hydrocortisone). Enzyme induction occurs in two distinct phases. During the first 12 hr after the addition of prednisolone, there is a small increase in alkaline phosphatase levels. After 15 to 24 hr, the enzyme activity shows a sudden, marked linear rise, reaching a maximum at 60 to 80 hr. Puromycin blocks enzyme induction immediately, even when added during the period of rapid increase of enzyme. Actinomycin D blocks induction when added no later than 8 hr after the addition of prednisolone. On the other hand, Actinomycin D added during the phase of rapid enzyme induction has no effect for at least 12 hr. These findings suggest that de novo protein synthesis is involved in prednisolone induction of alkaline phosphatase and that the RNA messenger for this enzyme is relatively stable.     

Effect of pancreatic polypeptide-antiserum on bombesin-stimulated pancreatic exocrine secretion in dogs

Bombesin is a potent stimulus of both pancreatic protein secretion and plasma pancreatic polypeptide (PP) release in dogs. Physiological plasma levels of PP have been shown to inhibit pancreatic exocrine secretion in dogs. We examined the question whether the concomitant release of PP exerts a suppressive action on the pancreatic exocrine response to bombesin in dogs by measuring pancreatic exocrine secretion with and without in vivo immunoneutralization of PP with a high affinity PP-antiserum. Bombesin was infused in a dose of 150 ng/kg·hr, resulting in a rise of plasma PP from 24±5 to 224±25 pM (p<0.01). Before this bombesin infusion, 7 ml of normal rabbit serum had been administered to the dogs (n=8). At a later stage, the study was repeated after administration of 7 ml of PP-antiserum to the same animals. The bombesin induced increase in pancreatic exocrine secretion during administration of PP-antiserum (flow rate 24±10 ml/hr, protein output 1.35±0.43 g/hr, and bicarbonate output 3.25±1.42 mmol/hr) was not significantly different from that during control rabbit serum (flow rate 21±7 ml/hr, protein output 1.26±0.38 g/hr, and bicarbonate output 3.18±1.10 mmol/hr). It is therefore concluded that the pancreatic exocrine response to bombesin is not affected by the concomitant secretion of PP.     

Plasma concentrations of arginine vasotocin, prolactin, aldosterone and corticosterone in relation to oviposition and dietary NaCl in the domestic fowl

The osmolality and concentrations of Na, K, Cl and the hormones arginine vasotocin (AVT), prolactin, aldosterone and corticosterone were measured in plasma as functions of time in relation to oviposition, changing NaCl content of the diet, and feeding-inanition. AVT was significantly increased immediately after oviposition (but not during the hour before) with a calculated average value of 38.0 +/- 4.1 pg/ml at oviposition. A moderate increase in concentrations of prolactin and corticosterone were observed immediately after oviposition. Oviposition was not associated with detectable changes in plasma osmolality (and electrolyte concentrations) nor with the concentration of aldosterone. After a sudden change from a high NaCl diet to a low NaCl diet the plasma osmolality and concentrations of NaCl, AVT and prolactin reached new stable levels in 24 hr, whereas the plasma aldosterone concentration required more than 4 days to reach a steady level. After resalination plasma aldosterone was suppressed in less than 8 hr. Both osmolality and concentrations of AVT and prolactin showed transient overshoots during the first 24 hr. NaCl depletion resulted in a transient increase of corticosterone.     

External stimuli affecting incubation behavior and prolactin secretion in the duck (Anas platyrhynchos)

The importance of general environmental, including visual and tactile, stimuli on behavior and prolactin secretion during the incubation phase of reproduction in the duck (Anas platyrhynchos) was investigated. Nest occupancy rapidly increased at the end of egg laying and marked the initiation of incubation. Two recesses from the nest each day were synchronized to dawn and dusk; the median occurrence was 0.23 hr after dawn and 1.17 hr before dusk. Mean recess length was 36.1 +/- 1.9 min at dawn and 40.5 +/- 2.1 min at dusk. Plasma prolactin concentrations during incubation, 25.8 +/- 2.3 ng/ml, decreased to baseline levels, 10.8 +/- 1.9 ng/ml, within 24 hr after nestbox removal. The withdrawal of tactile, but not visual, stimuli of the clutch during incubation by either anesthesia or denervation of the incubation patch caused significant decreases in prolactin plasma concentrations within 24 hr. Prolactin plasma concentrations decreased rapidly at the end of incubation in ducks which successfully hatched young as well as in unsuccessful incubators. Temperature manipulations of the clutch, either above or below normal, caused decreases in plasma prolactin concentrations in parallel with temperature modification.     

Intrarenal haemodynamics in postobstructive diuresis in the dog

Intrarenal haemodynamics were investigated in the dog prior to and after relief of 24 hr bilateral ureteral ligation (BUL), by the radioactive microsphere technique. Prior to release of 24 hr BUL there was an about 50% reduction in total blood flow (RBR), with a nearly proprotional decrease in the perfusion of the four cortical layers. Following release of the obstruction, total renal and outer cortical (zones 1 and 2) blood flow remained diminished, while perfusion of the inner (juxtamedullary) layers (zones 3 and 4) increased as compared to its prerelease values and equalled controls. Glomerular filtration rate (GFR) amounted to about 27% of controls in the postrelease phase. A marked increase in absolute and fractional sodium water excretion was observed after release of 24 hr BUL, as contrasted to normal controls and dogs after 24 hr unilateral ureteral ligation (UUL). This state, designated as postopstructive diuresis, might be explained by redistribution of intrarenal blood flow towards the juxtamedullary zones, and by a powerful natriuretic substance accumulated during complete obstruction.     

Hormonal requirements for the larval-pupal transformation of the epidermis of Manduca sexta in vitro

In the tobacco hornworm, Manduca sexta, metamorphosis occurs in response to two releases of ecdysone that occur 2 days apart. Epidermis was explanted from feeding final-instar larvae before the first release of ecdysone and was cultured in Grace's medium. When exposed to 1 μg/ml of β-ecdysone for 24 hr and then to hormone-free medium for 24 hr, followed by 5 μg/ml of β-ecdysone for 4 days, the epidermis produced tanned pupal cuticle in vitro. During the first 24 hr of exposure to β-ecdysone, the epidermis first changed its cellular commitment to that for pupal cuticle formation (ET₅₀ = 14 hr), then later (by 22 hr) it became committed to tan that cuticle. Then, for most of the pupal cuticle to be tanned, at least a 12-hr period of culture in hormone-free medium was required before the cuticle synthesis was initiated. Consequently, some events prerequisite to sclerotization of pupal cuticle not only occur during the ecdysone-induced change in commitment but also during the ecdysone-free period. When the tissue was preincubated in 3 μg/ml of juvenile hormone (JH I or a mimic epoxygeranylsesamole) for 3 hr and then exposed to both ecdysone and juvenile hormone for 24 hr, it subsequently formed larval cuticle. The optimal conditions for this larval cuticle formation were exposure to 5 μg/ml of β-ecdysone in the presence of 3 μg/ml of epoxygeranylsesamole for 48 hr. When the epidermis was cultured in Grace's medium for 3 days and then exposed to 5 μg/ml of β-ecdysone for 4 days, 70% of the pieces formed pupal cuticle. By contrast, if both ecdysone and JH were added, 77% formed larval cuticle. Therefore, the change from larval to pupal commitment of the epidermal cells requires not only the absence of JH, but also exposure to ecdysone.     

INTERACTION OF ESTROGEN AND PROGESTERONE IN CHICK OVIDUCT DEVELOPMENT : I. Antagonistic Effect of Progesterone on Estrogen-Induced Proliferation and Differentiation of Tubular Gland Cells

Daily administration of estrogen to immature female chicks results in marked oviduct growth and appearance of characteristic tubular gland cells which contain lysozyme. Although a rapid increase in total DNA and RNA content begins within 24 hr, cell specific protein, lysozyme, is first detectable after 3 days of estrogen. Progesterone administered concomitantly with estrogen antagonizes the estrogen-induced tissue growth as well as appearance of tubular gland cells and their specific products, lysozyme and ovalbumin. When the initiation of progesterone administration is delayed for progressively longer periods (days) during estrogen treatment, proportionally greater growth occurs with more lysozyme and tubular gland cells after 5 days of total treatment. Progesterone does not inhibit the estrogen-stimulated increase in uptake of α-aminoisobutyric acid and water by oviduct occurring within 24 hr or the estrogen-induced increase in total lipid, phospholipid, and phosphoprotein content of serum. The above results of progesterone antagonism can best be explained by the hypothesis that progesterone inhibits the initial proliferation of cells which become tubular gland cells but does not antagonize the subsequent cytodifferentiation leading to the synthesis of lysozyme and ovalbumin once such cell proliferation has occurred.     

Biogenesis of mammalian mitochondria in the renoprival kidney. I. Amino acid incorporation and respiratory activity

Changes in the yield of mitochondrial protein, in the incorporation of leucine into mitochondrial proteins, and in the respiratory activity of isolated mitochondria were determined in the remaining kidney (renoprival kidney) of the rat during the first 72 hr postmononephrectomy. At 24, 48, and 72 hr the yield of mitochondrial protein isolated from the renoprival kidney increased 13, 23, and 34%, respectively, whereas renal mass increased 9, 14, and 19%. Incorporation of [³H]-leucine in vivo into total mitochondrial protein was increased 96 and 130% over control at 12 and 24 hr, respectively. Incorporation of leucine in vitro by mitochondria was increased 27% over control at 24 hr; chloroamphenicol, but not cycloheximide, inhibited the in vitro incorporation.     

Rhipicephalus sanguineus: sequential histopathology at the host-arthropod interface

The reaction beneath the mouth parts of an adult, female Rhipicephalus sanguineus attached to a dog develops progressively over 4–5 days. The cement substance is confined to the external surface of the epidermis and does not form any organized structure in the dermis. The hypostome is imbedded in the cement substance and does not penetrate the epidermis. The cheliceral shafts are at the epidermal-dermal junction and do not extend into the dermis to any degree. Thus, it is the adhesive quality of the cement for the dog's skin that holds this tick firmly attached to its host.Edema of the epidermis appears 24 hr after attachment of the tick; the dermal infiltrate becomes prominent from 24 hr after attachment onward and initially consists of polymorphonuclear leukocytes. This cell type predominates until the tick has detached. Rupture of lymphatics occurs and infiltrated cells can be found entering these open channels. Degranulation of mast cells is associated with polymorphonuclear leukocytic infiltration. A cavity develops in the dermis progressively over the period of tick attachment and feeding. This cavity appears during the first 24 hr and its full development depends upon leukocyte infiltration and the feeding activity of the tick. During the healing phase, macrophages, lymphocytes and fibroblasts gradually replace the polymorphonuclear leukocytes. The dermis is still hypercellular in the area of former attachment 2 wk after a female tick has detached fully engorged. The dog does not appear to develop resistance to the tick's engorgment even after 2 yr of intermittent exposure, nor does the host's reaction hinder the tick's engorgment. A dog never before exposed to arthropods of any kind reacted, histologically, to tick exposure with a very similar infiltration of polymorphonuclear leukocytes as seen in dogs repeatedly exposed. It is suggested that the inflammatory response by the host to the feeding tick may play an important role in the development and spread of infectious agents transmitted by this pool feeding arthropod.     

CHANGES IN SENSITIVITY OF MAIZE CHROMOSOMES TO X RAYS DURING SEED GERMINATION

Latterell , Richard L., and Dale M. Steffensen . (Brookhaven Natl. Lab., Upton, L. I.. N. Y.) Changes in sensitivity of maize chromosomes to X rays during seed germination. Amer. Jour. Bot. 49(5): 472–478. Illus. 1962.—Changes in the radiosensitivity of maize seeds during early stages of germination were studied by means of somatic-mutation techniques. Seeds heterozygous for the yg₂ (yellow-green) locus were irradiated with 800 r of X rays after soaking in running tap water up to 42 hr. Yellow-green sectors, representing mutations affecting the dominant yg₂ locuss in leaves 4 and 5 of seedling plants were used as a criterion of radiosensitivity. The frequency of somatic sectors was virtually nil for dry seed and for seeds soaked up to 16 hr. Sector frequencies underwent a marked (9- to 15-fold) rise from 16 to 28 hr, reached a plateau of sensitivity and subsequently declined. Manometric studies were conducted on seeds soaked under the same conditions as those irradiated. The rate of oxygen consumption rose rapidly from 0 to 7 hr, remained essentially constant from 7 to 16 hr, then underwent an approximately 2-fold increase from 16 to 24 hr, after which the rate of progressive increase was retarded. The fact that the marked rise in frequency of X-ray-induced somatic sectors coincided with the major increase in oxygen consumption suggests that radiosensitivity of soaked seeds is conditioned by metabolic changes during seed development. Changes in radiosensitivity that followed attainment of peak sector frequencies were apparently governed by factors that influenced the rate of seed development.     

5 alpha-Cholest-8(14)-en-3 beta-ol-15-one. In vivo conversion to cholesterol upon oral administration to a nonhuman primate

The metabolism of 5 alpha-cholest-8(14)-en-3 beta-ol-15-one (I), a potent inhibitor of cholesterol synthesis with marked hypocholesteremic activity, has been studied in a nonhuman primate. A mixture of [2,4-3H]-I and [4-14C]-cholesterol was administered to a male baboon in the form of a feedball. Blood was samples at 4, 8, 12, 16, and 24 hr. Detailed analyses of the plasma lipids indicated very rapid absorption of I (relative to cholesterol) and metabolism to cholesterol, cholesteryl esters, and esters of I. The labeled cholesterol was characterized by chromatographic techniques and by purification by way of its dibromide derivative. The levels of 3H in plasma associated with I, esters of I, cholesterol, and cholesteryl esters each showed a different time course. By 24 hr after the administration of [2,4-3H]-I, most of the 3H in plasma was associated with cholesterol and cholesteryl esters. The levels of total 3H and 14C in plasma at various times after the administration of the mixture of [2,4-3H]-I and [4-14C]-cholesterol differed markedly with 3H showing a maximum value at 4 hr and 14C showing a maximum value at 24 hr.     

Relationship of glutamate dehydrogenase levels to free amino acids, amides and ammonia in excised oat leaves

Levels of glutamate dehydrogenase (GDH) increase 12 fold indetached oat leaves during 96 hr incubation with 15 mM ammonia.The slight elevation of GDH detected within the first 24 hrwas followed by increasing rates of enzyme production in subsequentperiods. Rapid increases in free ammonia and amino acids witha marked synthesis of glutamine and decreased of glutamate andaspartate were observed during the initial stages of ammoniumassimilation. (Received December 26, 1973; )     

Photoperiodic induction in quail as a function of the period of the light-dark cycle: implications for models of time measurement.

The earliest detectable event in the photoperiodic response of quail is a rise in luteinizing hormone (LH) secretion beginning at about hour 20 on the first long day. The timing of this rise was measured in castrated quail after entrainment to short daylengths which cause significant phase angle differences in the circadian system: (1) LD 2:22 and LD 10:14, and (2) LD 3:21 (T = 24 hr) and LD 3:24 (T = 27 hr). The quail were then exposed to 24 hr of light (by delaying lights-off), and the time of the first LH rise was measured; it was similar in all schedules. Quail were also entrained to LD 3:21 or LD 3:24 and then given a single 6-hr nightbreak 6-12, 7-13, or 13-19 hr after dawn. The earlier pulse was marginally more inductive in the 27-hr cycle. Thus the entrainment characteristics of the photoinducible rhythm (phi i) in quail appear very different from those of the locomotor circadian rhythm, and raise doubts as to whether phi i is a primary circadian oscillator.     

Circadian variations in plasma growth hormone and prolactin in the infant rat: Comparison with the adult pattern

Radioimmunoassayable (RIA) plasma growth hormone (GH) and prolactin (PRL) levels were determined at 3 hr intervals during a controlled 24-hr light-dark cycle in 10-day-old male and female rats; parallel measurements were made of brain monoamines (MA's), dopamine (DA), norepinephrine (NE) and serotonin (5-HT) concentration. Plasma GH and PRL and brain MA levels found in infant rats were compared to the same determinations made during the 24-hr cycle in 50-day-old male rats. GH levels were rather uniform and did not show circadian periodicity in the plasma of infant rats, while PRL levels showed a diurnal surge in the late afternoon hr (1800). In adult rats, GH levels exhibited wide fluctuations during the 24-hr cycle and no circadian periodicity, while PRL levels showed one diurnal (1500–1800) and one nocturnal (2400) surge. A pulsatile GH secretion was found in adult rats sampled at 15 min intervals over a period of 2 hr, which seemed to be lacking in infant rats. In the brain of infant rats, DA and NE levels exhibited circadian patterns which resembled the ones present in the brain of adult rats, whereas no circadian variations were present in 5-HT levels.     

In vitro synthesis of peritrophic membranes of the blowfly, Calliphora erythrocephala.

Tyrode solution containing added glutamine and Leloup's medium 1 has been used as a basic medium for the in vitro culture of the so-called proventriculus of adult Calliphora erythrocephala to elucidate some of the factors controlling the synthesis of peritrophic membranes (PM) in vitro. The formation rate was chosen as a quantitative criterion for the evaluation of the modifications of the incubation media.After systematic variation of osmolarity, pH, and temperature optimal formation rates were obtained in media with an osmolarity of 320 to 360 mOsmol, a pH of 6·8, and an incubation temperature of 27°C. Under these conditions the average rate of formation was in the modified Tyrode solution 3·0±1·1 mm PM/hr, and in Leloup's medium 3·6±0·8 mm PM/hr. In the modified Tyrode solution the formation of PM was complete after 5 to 7 hr, whereas in Leloup's medium it continued up to 24 hr. The addition of β-ecdysone caused an increase of the formation rate of PM to 4·5 to 5·5 mm PM/hr.The results obtained led to the hypothesis that an osmotically regulated enzyme system could be the limiting factor of the formation rate of peritrophic membranes, i.e. a system which could regulate the internal osmolarity of the formative cells by the interconversion of a bulk polymer and its monomer which are needed for the synthesis of PM.     

Forty-eight hours hypothermic storage of whole canine pancreas allografts. Improved preservation with a colloid hyperosmolar solution.

This study indicates that crystalloid (Sacks') and colloid (modified silica gel fraction of plasma, MSGF) hyperosmolar solutions are edequate means to preserve whole pancreas allografts under hypothermia (4 to 7 °C) for 24 hr. These groups of preserved canine pancreas allografts survived as long as the fresh transplanted pancreas. However, when the preservation was extended to 48 hr, the crystalloid hyperosmolar solution did not protect the pancreas allografts, but the colloid hyperosmolar solution gave similar results to fresh pancreas allografts.