Scanning electron microscope studies of the papilla basilaris of some turtles and snakes

The papillae basilares of three species of turtles and four species of snakes were studied by SEM. The papillae of turtle are relatively large among reptiles and are characterized by a long, horizontal middle section resting on wide basilar membrane. Both terminal ends of the papilla extend onto the surrounding limbus in the form of a forked or "T" -shaped end or as a curved, "hook"- like processes. Details vary with the species. In the three species of turtles studied, there were between 1,100 and 1,400 hair cells on a papilla. The tectorial membrane covering the horizontal portion of the papilla is heavy in appearance and tightly attached to the kinocilial bulbs. The terminal ends of the papilla are covered by a thin gelatinous material. In addition, mat-like tectorial network covers the supporting cells and extends from the microvilli of the supporting cells to the overlying tectorial membrane. All hair cells are unidirectionally and abneurally oriented. The supporting cell surfaces form a large part of the papilla and, thus, hair cell density is low. The papillae of the two boid snake species studied are moderately long among snakes and contain a moderate number of hair cells (574 in Epicrates and 710-780 in Constrictor). Papillar form is elongate, avoid, or canoe-shaped. The tectorial membrane may be either highly fenestrated or moderately dense and covers all but a few of the terminal hair cells. A tectorial-like mat covers all but a few of the terminal hair cells. Most hair cells are unidirectionally and abneurally oriented. A few terminal cells in boids may show reverse orientation. Hair cell density is similar to that of turtles.     

Chronic Hepatitis Associated with Drug Abuse: Significance of Hepatitis B Virus

One hundred and seventy-seven former heroin addicts, consisting of 85 who were newly admitted to a methadone maintenance program and 92 who had received methadone for a mean period of 30 months, were prospectively studied for up to 2 years in order to determine: (1) the effect of heroin withdrawal on the hepatic abnormalities, and (2) the incidence of HBsAg, anti-HBs, and anti-HCc as indices of the frequency of hepatitis B virus infection. Our study indicates that (1) hepatic abnormalities persist when heroin is discontinued and are not temporally related to drug and/or needle usage, and (2) that 71% of subjects had either HBsAg or anti-HBs; anti-HBc was tested for in 16 patients and was present in 100%, although 9 of the 16 were both HBsAg- and anti-HBs-negative. This study suggests that hepatitis B is largely responsible for the liver dysfunction. It is proposed that an abnormality in immune function, induced by heroin, is responsible for the high incidence of chronic hepatitis. Attention is drawn to the similarity between former drug addicts and hemophiliacs, since both develop chronic hepatitis in spite of anti-HBs in the serum.     

Preparation and crystal structure of [NEt4]3[Fe6W2S8(SEt)9]; structural and electrochemical comparisons with its molybdenum analogue

[NEt₄]₃[Fe₆M₂S₈(SEt)₉] (M = Mo or W) compounds are isomorphous and contain molybdenum and tungsten atoms in an essentially identical environment. These complexes undergo an irreversible one-electron oxidation at −0.46 V (Mo) and −0.51 V (W) and two one-electron reductions at −1.56 and −1.76 V (Mo) and −1.52 and −1.84 V (W), in DMSO solution versus (0.1 M). The only distinction between the behavior of these molybdenum and tungsten complexes identified thus far is that, for the former the reductions are reversible whereas for the latter they are irreversible. This difference may be relevant to the low activity found for nitrogenases reconstituted with tungsten in place of molybdenum.     

Ultrastructure of the muscles of the dorsal diaphragm in Locusta migratoria

Summary The alary muscles of Locusta migratoria adults make up the major tissue of the dorsal diaphragm which separates pericardial and perivisceral sinuses in the abdomen. The alary muscles are striated with a sarcomere at rest measuring about 9 m. The Z-line has a staggered-beaded arrangement with A-bands and I-bands readily discernable. Thick myofilaments are surrounded by 10 or more thin filaments. The sarcoplasm has few mitochondria near the area of the Z-line, dyads are present and sarcoplasmic reticulum is poorly developed. Axons which innervate the alary muscle are either contained within invaginated folds of the sarcolemma of the muscle cells or the muscle cells send finger-like projections to envelop the axons. The synaptic terminals contain synaptic vesicles between 40 and 45 nm in diameter and a few electron-dense granules near or less than 170 nm in diameter. Away from synaptic terminals the axon profiles show few or no granules. The axons are accompanied everywhere by well-developed glial cells. This then is not typical neurosecretomotor innervation, however, the presence of electron-dense granules suggests the possibility of peptidergic neurotransmission.     

PaeExo IX: a unique deoxyribonuclease from Pseudomonas aeruginosa active in the presence of EDTA.

A new deoxyribonuclease, PaeExo IX, has been purified to electrophoretic homogeneity from extracts of Pseudomonas aeruginosa strain PAO. This enzyme, which is active in the presence of EDTA, is equally efficient in hydrolyzing native and heart-denatured DNA to acid-s-luble products. The enzyme is partially or totally inhibited by the presence of several divalent cations. The active protein has a molecular weight of 1.6 +/- 0.1 x 10(5) and is composed of two nonidentical polypeptides with molecular weights of 78,000 and 69,000.     

Modulation of erythropoietin concentrations by manipulation of hypercarbia.

The present studies were done to determine whether preventing the respiratory alkalosis, which is known to occur with acute "hypoxic" stimuli, would lead to alterations in plasma concentrations of erythropoietin (Ep). Rats were subjected to two acute stresses, hypoxia and blood loss, separately and in combination, with and without the added stress of hypercarbia. Hypercarbia in all experimental groups was associated with a decrease in plasma concentrations of Ep. This reduction in plasma Ep with hypercarbia could not be fully explained by the higher arterial pO2S or p50S of the hypercarbic rats. Hypercarbia may have indirectly suppressed Ep production by increasing blood flow to the site of Ep production. Alternatively, the cell of origin of Ep could be sensitive to changes in pH and/or PCO2. It was further demonstrated that neither the onset nor the degree of reticulocytosis could be predicted by the plasma Ep concentrations. It is likely that the removal of red blood cells led to a decrease in marrow transit time with the early emergence of reticulocytes after acute blood loss.     

Localization of the nucleolar organizer by computer-aided analysis of a variant no. 21 in a human isolate

Summary A variant chromosome no. 21 consisting of two stalks and two satellites in tandem was detected during a survey of a human isolate. The variant segregated in three generations of a large kindred. One male had the variant no. 21, a metacentric Y, and a 47, XXY complement; however, no other evidence of chromosomal nondisjunction was found. Computer-aided analysis of sequentially stained variant no. 21 chromosomes indicated that silver-stained material corresponded to the proximal stalk region (as defined defined by Giemsa). These data support the hypothesis that human nucleolar organizers are localized to the stalks of acrocentric chromosomes.     

Control of respiration in proteoliposomes containing cytochrome aa3. I. Stimulation by valinomycin and uncoupler

1. Both valinomycin and p-trifluoromethoxy carbonyl cyanide phenylhydrazone (FCCP) are required for full release of respiration by cytochrome c oxidase-containing proteoliposomes (prepared by sonicating beef heart cytochrome aa₃ in salt solution with 4 parts phosphatidylcholine, 4 parts phosphatidylethanolamine and 2 parts cardiolipin) in the presence of external ascorbate and cytochrome c. In the absence of valinomycin the response to FCCP is rather sluggish, as reported by Wrigglesworth et al. (1976) (Abstracts, 10th Int. Congr. Biochem., No. 06-6-230).2. The K_m for cytochrome c in 67 mM, pH 7.4, phosphate buffer with ascorbate as substrate, was 9 μM in both absence and presence of valinomycin and FCCP. Energization thus acts non-competitively towards cytochrome c oxidation.3. The apparent K_m for oxygen is greater in the energized than in the deenergized state; double reciprocal plots of respiration rate versus oxygen concentration are concave downward in the absence of uncouplers, as found with intact mitochondria. Energization thus acts “competitively” towards oxygen.4. Despite the lack of a functional ATPase system, all the kinetic features of energization found in intact mitochondria can be mimicked in the reconstituted liposomes. This supports the chemiosmotic idea that electrical and perhaps H⁺ gradients modify the oxidase activity in reconstituted vesicles.     

The influence of cellular amino acids and the Na+: K+ pump on the membrane potential of the Ehrlich ascites tumor cell

The membrane potential of the Ehrlich ascites tumor cell was shown to be influenced by its amino acid content and the activity of the Na⁺: K⁺ pump. The membrane potential (monitored by the fluorescent dye, 3,3′-dipropylthiodicarbocyanine iodide) varied with the size of the endogenous amino acid pool and with the concentration of accumulated 2-aminoisobutyrate. When cellular amino acid content was high, the cells were hyperpolarized; as the pool declined in size, the cells were depolarized. The hyperpolarization seen with cellular amino acid required cellular Na⁺ but not cellular ATP. Na⁺ efflux was more rapid from cells containing 2-aminoisobutyrate than from cells low in internal amino acids. These observations indicate that the hyperpolarization recorded in cells with high cellular amino acid content resulted from the electrogenic co-efflux of Na⁺ and amino acids.Cellular ATP levels were found to decline rapidly in the presence of the dye and hence the influence of the pump was seen only if glucose was added to the cells. When the cells contained normal Na⁺ (approx. 30 mM), the Na⁺: K⁺ pump was shown to have little effect on the membrane potential (the addition of ouabain had little effect on the potential). When cellular Na⁺ was raised to 60 mM, the activity of the pump changed the membrane potential from the range ?25 to ?30 mV to ?44 to ?63 mV. This hyperpolarization required external K⁺ and was inhibited by ouabain.