Structure-activity relationships in corpora allata of the cockroach Diploptera punctata: roles of mating and the ovary

Morphometric studies were made on corpora allata of the cockroach Diploptera punctata from animals in which increasing gland size is not coupled to hormone synthesis (ovariectomized mated females; last-instar larvae) and in which gland size is coupled to hormone synthesis (normal mated and virgin females; penultimate-instar larvae). Cell number, gland volume, and juvenile hormone synthesis were measured. From electron micrographs, nuclear, cytoplasmic, and extracellular volumes; and cell membrane area were calculated; and fine structure described. Low-activity glands of ovariectomized mated females resembled high-activity glands from mated females in high cell number, large overall and cytoplasmic volume, and low nuclear-cytoplasmic ratio; they differed in having organelles typical of low-activity glands, mitochondria with dense matrices and large whorls of smooth endoplasmic reticulum. Inactive lastinstar larval glands resembled mated ovariectomized, female glands in increased cell number and organelles characteristic of inactive glands; however, their nuclearcytoplasmic volume ratio was much higher. Penultimate cytoplasmic volume ratio was much higher. Penultimate larval glands with high activity per cell resembled active glands of normal mated females. Ovariectomy did not change morphometric parameters of virgin female glands; thus mating results in increase in size of adult female glands whereas the growing ovary is needed for changes in mitochondria and endoplasmic reticulum associated with high juvenile hormone synthesis.     

幼年蝙蝠下丘神经元的听空间特性

实验分别在出生后４周龄的幼年和成年鲁氏菊头蝠（Ｒｈｉｎｏｌｏｐｈｕｓｒｏｕｘｉ）上进行。使用移动声刺激装置,高频喇叭可在动物头部前方水平方向１８０度、垂直方向６０度的范围内移动。玻璃微电极记录单个神经元的听反应。实验考察了幼年和成年动物下丘神经元的听空间特性,共观察了３０１个神经元,其中幼年动物１４８个,成年动物１５３个。结果表明,４周龄的幼年动物下丘听神经元已表现出方向敏感性,即每个听神经元均有一个特定的最佳反应中心和反应域。但神经元听反应中心在听空间的分布相当弥散,大多数位于对侧水平方向２０—８０度、垂直方向上下１５度范围内。而成年动物听神经元反应中心的分布则相当集中,局限地分布于对侧水平方向２８－５０度,垂直方向０—１０度范围内,两者构成明显差异。     

大水体池塘培育革胡子鲶稚鱼的研究

本文报道在云南南亚热燕山区大水体池塘中,用人工施肥培养浮游动物,作为革胡子鲶稚鱼的开口饵料及其形成夏花鱼苗的动物性饲料是可行的。对孵出四日龄的稚鲶进行培育,在水温２３．２－３０．３℃时,可使十七日龄稚鲶达到夏花水平,存活率达６０％以上,研究结果表明,四日龄稚鲶口宽为７６０－９００μｍ,开口期及生长前期主要摄取枝角类、桡足类和摇蚊幼虫。稚鲶生长后期,对轮虫、水生昆虫幼体及配合饲料的摄取量增加,而摄食     

Phosphorylation of a 16-kDa protein by diacylglycerol-activated protein kinase C in vitro and by vasopressin in intact hepatocytes

A replication-defective Simian virus 40 genome, with a deletion of about 120 nucleotides in the region encoding the N-terminal fourth of the large T antigen, has been isolated from the DNA of Simian cells transformed by SV40. Both the original transformants, and the murine transformants obtained by transfection with this cloned mutant DNA, produced a large T antigen displaying in immunofluorescence an exclusively cytoplasmic localization. The protein apparent molecular mass (83 kDa) was about 6% smaller than that of normal karyophilic large T. Restriction analysis showed that the deletion eliminated two close HinfI sites, at nucleotides 4459 and 4376 (map unit 0.50).     

Thyroid hormone: Aldosterone antagonism in cultured epithelial cells

Thyroid hormone (T₃) has been demonstrated to inhibit the action of aldosterone on sodium transport in toad urinary bladder and rat kidney. We have exammined the effect of T₃ on aldosterone action and specific nuclear binding in cultured epithelial cells derived from toad urinary bladder. In cell line TB6-C, addition of 5·10⁻⁸ M T₃ to culture media for up to 3 days results in no change in short-circuit current or transepithelial resistance. This concentration of T₃ completely inhibits the maximal increase in short-circuit current in response to 1·10⁻⁷ M aldosterone. The inhibition can be demonstrated with 18 h preincubation or with simultaneous addition of T₃ and aldosterone. The half-maximal concentration for the inhibition of the aldosterone effect is approx. 5·10⁻⁹ M T₃. T₃ has no effect on cyclic AMP-stimulated short-circuit current in these cells. The effect of T₃ on nuclear binding of [³H]aldosterone was examined using a filtration assay with data analysis by at least-squares curve-fitting program. Best fit was obtained with a model for two binding sites. The dissociation constants for the binding were K′_d1 = (0.82 ± 0.36)·10⁻¹⁰ M and K′_d2 = (3.2±0.60)·10⁻⁸ M.The half-maximal concentration for aldosterone-stimulated sodium transport in these cells is approx. 1·10⁻⁸ M. Analysis of nuclear aldosterone binding in cells preincubated for 18 h with 5·10⁻⁸ M T₃ showed a K′_d1 = (0.15 ± 0.10)·10⁻¹⁰ M and K′_d2 = (3.5 ± 0.10)·10⁻⁸ M. We conclude that T₃ i action of aldosterone on sodium transport at a site after receptor binding in the nucleus.     

Amino acid transport in the rat exocrine pancreas

Summary Amino acid transport and incorporation have been studied in vitro in rat pancreatic lobules after maximal and supramaximal hormonal stimulation with caerulein. Incorporation into proteins was increased already after 30 and 120 min of maximal stimulation, but was decreased after the infusion of a supramaximal dose. Uptake of neutral amino acids was monitored using labeled leucine and -aminoisobutyric acid (AIB). In the case of leucine the free pool was consistently reduced after maximal stimulation, while supramaximal doses led to an increase which could be potentiated by the addition of 2mM tetracaine. Using AIB, a significant increase in the intracellular pool was observed after maximal stimulation, conversely a decrease after supramaximal stimulation. Release of labeled leucine and AIB from preloaded lobules during incubation in the cold was significantly reduced after maximal secretory stimulation, but was found enhanced by 200 to 300 percent after supramaximal stimulation. No fine structural alterations at junctional complexes or at both the lateral and luminal plasma membranes were observed after maximal stimulation except an increased number of exocytotic figures at the luminal face. However, supramaximal stimulation led to progressive rarefaction of the tight junctional network and disintegration of the gap junctions. Concomitantly, an equal distribution of membrane particles on both faces of the plasma membrane together with a random occurrence of exocytotic figures were observed.Supported by a grant from the Deutsche Forschungsgemeinschaft, Bonn-Bad Godesberg (SFB 122, project C 5). Dedicated to Professor Dr. Gerhard Petry, Marburg, on the occasion of his 65th birthday     

Moulting hormone,juvenile hormone and the ultrastructure of the fat body of adult Sarcophaga bullata (Diptera)

Summary In the ovoviviparous fly, Sarcophaga bullata, vitellogenesis is cyclic; a process reflected in ultrastructural changes in the fat body cells and oenocytes. At eclosion the larval fat body has not yet completely disappeared. During vitellogenesis the fat body cells are specialized for intensive protein synthesis showing a very extensive RER and numerous invaginations of the plasma membrane. These features disappear when the eggs descend into the oviducts to complete embryogenesis. The predominant feature of the oenocytes is their very prominent SER. The fat body cells of the males are never as specialized for protein synthesis as those of the females. Feeding of ecdysterone to males for 3 or more days induces a rather extensive subcellular apparatus for protein synthesis, i.e., invaginations of the plasma membrane and an extensive RER. Juvenile hormone is completely ineffective in this respect. Both ecdysterone and juvenile hormone have pronounced but different effects on the oenocytes of males.     

Ultrastructural localization of juvenile hormone biosynthesis by insect corpora allata

Summary The conversion of exogenous ³H-farnesenic acid to ³H-methyl farnesoate and ³H-C₁₆ juvenile hormone (JH) has been followed in the corpus allatum (CA) cells of the desert locust Schistocerca gregaria by means of electron microscopic autoradiography. Aerobic and anaerobic chase incubations have been used to modify the quantities of these three compounds within the CA cells. Under all incubation conditions, radiolabel is found associated almost exclusively with the subcellular membrane systems — smooth endoplasmic reticulum (SER) and Golgi elements —and with the mitochondria. CA cells are probably similar to vertebrate steroid-synthesizing cells in that the secretory product is synthesized in the SER and mitochondria.Radiolabel was found to be present in all cells of the CA suggesting that all cells are capable of at least the final two stages of JH biosynthesis (the esterification and epoxidation of ³H-farnesenic aid). This indicates that JH biosynthesis may be regulated through changes in the biosynthetic capabilities of individual cells rather than through changes in the total number of cells engaged in biosynthesis. Radiolabel was not observed to be associated with any distinctive cellular product, a result which provides additional evidence for the suggestion that the release of JH from the CA is governed by laws of simple physical diffusion.Supported by operating grants from the National Research Council of Canada to SST and ASMS. ³H-farnesenic acid was supplied by the late Dr. A.F. White of the Unit of Invertebrate Chemistry and Physiology, A.R.C., University of Sussex. We thank Dr. G.E. Pratt for helpful discussions     

Abscisic acid and apical dominance in Phaseolus coccineus L.

Abscisic acid (ABA) in lanolin, applied to the internode of decapitated runner bean plants enhances the outgrowth of lateral buds. The optimum concentration of the paste is 10^-5 M. The effect of ABA is counteracted by indoleacetic acid (IAA) but not by gibberellic acid (GA₃). There is no effect when ABA is applied to the apical bud or lateral buds of intact plants. However, 13.2 ng given to the lateral buds of decapitated plants stimulate their growth, whereas higher concentrations are inhibitory. Consequently, ABA enhances growth of lateral buds directly, but only when apical dominance is already weakened. The growth of the decapitated 2^nd internode was not affected by ABA. Radioactivity from [2-¹⁴C] ABA, applied to nonelongating 2^nd internode stumps of decapitated runner bean plants moves to the lateral buds, whereas [1-¹⁴C]IAA-and [³H]GA₁-translocation is much weaker. ABA transport is inhibited if IAA or [³H]GA₁ is applied simultaneously. In elongating internodes [¹⁴C]ABA is almost completely immobile. [¹⁴C]IAA-and [³H]GA₁-translocation is not affected by ABA. The amount of radioactivity from labelled ABA, translocated to the lateral buds, is highest during the early stages of bud outgrowth.Abbreviations ABA 2,4-cis, trans-(+)-abscisic acid - GA gibberellic acid - IAA indoleacetic acid - p.l. plain lanolin     

In vitro cytokinin binding to a particulate cell fraction from protonemata of Funaria hygrometrica

Cytokinin-induced bud formation in moss protonemata is specific for cytokinin bases, their ribosides being relatively inactive. Binding of [³H]benzyladenine (BA) to a 13,000–80,000 x g subcellular fraction from extracts of Funaria hygrometrica (L.) Sibth. was measured by a centrifugation assay. Increasing concentrations of non-radioactive BA decreased the binding proportionally to the logarithm of the BA concentration between 3×10^-8 and 10^-4M. [³H]Zeatin also bound to these fractions, although the extent of binding was not as great as with [³H]BA. Biologically active cytokinins, including BA, zeatin, 6-(3-methyl-2-enylamino)purine (IPA) and kinetin, competed for the binding of [³H]BA, whereas the ribosides of BA, zeatin and IPA competed poorly. Other biologically inactive compounds, such as adenine and 9-methyl-BA, were also ineffective as competitors. The ability to bind BA by the 13,000–80,000 x g fraction was greatly reduced by treatment with 1% Triton X-100, and heat treatment eliminated more than one-half of the binding activity. Competitive binding appeared to be pH-dependent, with maximal activity between pH 6.0 and 6.5. After fractionation by differential centrifugation, the ability to bind cytokinins was not correlated with the RNA content of the fraction and thus probably did not represent binding to ribosomes which has been reported in other plant tissues. Cytokinins also exhibited competitive binding to non-biological materials, e.g., talc. The detailed characteristics of the binding of BA to talc were different from those to the biological fractions. However, the problem remains, in all studies of cytokinin binding, to distinguish between binding that is biologically meaningful, and biological (biologically) non-meaningful physical adsorption.Abbreviations BA N⁶-benzyladenine - IPA 6-(3-methyl-2-enylamino)purine - 9-MeBA N⁶-benzyl-9-methyladenine