Developmental aspects of the innervation of skeletal muscle fibers in the chick embryo

Summary The M. complexus in the chick, commonly called the hatching muscle, undergoes conspicuous growth during the latter stages of embryonic development. Myogenesis of this muscle was compared to that of M. biceps femoris with regard to development of types of muscle fiber and their innervation. In both muscles fibers are of relatively uniform size and show little growth in diameter between 12 days of development and hatching; fibers develop continuously and display a wide range of diameters at all stages.Initial thickenings on the sarcolemma of fibers where axons are closely approximate were first observed at 10 days of development in both muscles. In both muscles fibers are innervated prior to fibers. Terminal axon networks bridge intercellular spaces and contact fibers in different myogenic clusters, fibers that develop on the surface membrane of fibers exhibit focal thickenings of the membrane and some cell projections that are directed toward axon- fiber contacts. These changes occurred only in fibers of M. complexus.At 14 days of embryogenesis, the processes of synaptogenesis and of myelin formation are less advanced in M. biceps femoris than in M. complexus. At this stage a fibers were observed to be innervated in M. complexus, but not yet in M. biceps femoris. Each fiber was observed to be encircled by several preterminal axons.It is concluded that the earlier development of M. complexus is correlated with an equally early development of nerve-muscle interactions.This work was supported in part by a grant from the Muscular Dystrophy Association of America, Inc.Postdoctoral Fellow of the Muscular Dystrophy Association I would like to thank Professor Dr. H. Tamate for his valuable advise. I am also grateful to Dr. L. Doerr, H. Stokes and Judi K. Lund for their advice and skilled technical assistance     

Lethal genes on the sex chromosomes concealed in a population of the mosquito Aedes aegypti L.

A population has been examined in which an overall parity between the sexes hides considerable between-family variation in sex ratio. A proportion of families show highly distorted sex ratios, with either an excess of females or an excess of males. Distorted sex ratios are invariably associated with mortality in the immature stages at a level appropriate to the action of recessive lethal genes. It has been shown that 26% of M-bearing (Y) chromosomes and at least 24% of m-bearing (X) chromosomes carry a recessive lethal gene.Two such genes have been investigated. l kills males and, in a cross between two heterozygotes, gives rise to a sex ratio close to 2:1 (excess families). k kills females and, in a cross between two heterozygotes, gives rise to a sex ratio close to 1:2 (excess families). Selection for excess or excess did not increase the level of sex ratio distortion.No crossing over occurs between k and the M/m locus whereas l shows 5–10% recombination with M/m. A test for allelism confirmed that l and k are not allelic. The penetrance of k is complete whereas l shows somewhat less than full penetrance. The penetrance of l has been improved by selection.The high frequency of lethals remained in the population during the two year period of study. There was evidence for heterosis preserving this frequency, the heterozygotes living longer and producing more progeny. However lethals were no longer to be found after four further years of laboratory culture.     

Variations in the rate of synthesis of beta and beta'' RNA polymerase polypeptides under the influence of certain factors.

Summary In merodiploid cells containing a double dose of structural genes of RNA polymerase subunits-rpoBand rpoC-the rate of and subunits synthesis is 2 times higher than in haploidcells. Missence mutation rpoC1 (tsX) alters polypeptide and inducesthe and subunits synthesis at increased rate, particularly at a nonpermissive temperature. When rpoBCoperon carrying mutation rpoC1 is duplicated no dosage effect is observed. In the rpoC ⁺/rpoC1 heterodiploid the rpoC1 mutation does not significantly accelerate RNA polymerase subunits synthesis i.e. is recessive with respect to rpoC ⁺ Rifampicin causes 6-fold stimulation of RNA polymerase subunits synthesis in a sensitive wild-type strain. The rpoC1 mutation itself accelerates the synthesis of these subunits 3-fold. In the presence of rifampicin the mutant strain produces 13–22-fold faster as compared to wild-type strain without the drug. Thus, the effects of rifampicin and the mutation are multiplied suggesting that these factors act independently. Similar data have also been obtained with rifampicin-treated cells of rpoB22 (ts22) amber-mutant.After UV-irradiation of cells and synthesis is depressed much stronger than the total protein synthesis. Infection with a transducing phage rif ^d-47 which carries rpoB gene provokes a higher rate of synthesis. When pre-irradiated cells (500 erg/mm²) are infected with this phage, the rate of synthesis grows 20-fold compared to irradiated, non-infected cells and 6.5-fold compared to intact cells.The data are discussed in terms of the possible regulatory mechanisms of RNA polymerase subunit synthesis.     

Laser kinetic spectroscopy studies of the bimolecular oxygenation of alpha- and beta-subunits within the R-state of human hemoglobin

Bimolecular oxygenation of tri-liganded R-state human hemoglobin (HbA) is described by bi-exponential kinetics with association rate constants k = 27.2 ± 1.3 (M·sec)^-1 and k = 62.9 ± 1.6 (M·sec)^-1. Both the observed processes have been assigned to the bimolecular oxygenation of - and -subunits of the native tetrameric protein by molecular oxygen. The quantum yields of photodissociation within the completely oxygenated R-state HbA are = 0.0120 ± 0.0017 and = 0.044 ± 0.005 for - and -subunits, respectively. The oxygenation reactions of isolated ^PCMB- and ^PCMB-hemoglobin chains are described by mono-exponential kinetics with the association rate constants k = 44 ± 2 (M·sec)^-1 and k = 51 ± 1 (M·sec)^-1, respectively. The quantum yields of photodissociation of isolated ^PCMB- and ^PCMB-chains (0.056 ± 0.006 and 0.065 ± 0.006, respectively) are greater than that observed for appropriate subunits within the R-state of oxygenated HbA.     

Studies on the morphology and taxonomy of three new myxosporeans of the genus Sinuolinea Davis, 1917 (Myxosporea: Sinuolineidae) infecting the urinary bladder of some marine fishes from the Shandong coast,China

The morphology and taxonomy of three new species of myxosporeans (Myxosporea: Sinuolineidae), Sinuolinea shandongensis n. sp., S. argyrosomi n. sp. and S. platycephali n. sp., parasitising marine fishes collected from the Yellow Sea off the coast of southeast Shandong, China, were investigated. These species, including spores and plasmodia, were found in the urinary bladder of their hosts. The diagnostic features of the new species are as follows. S. shandongensis n. sp. from Nibea albiflora: monosporous and disporous plasmodia, 29–37 × 29–27 m; spore inversely pyramidal or spherical, with smooth surface and fine, highly sinuous sutural line, 16.4±2.4 (15–20) × 16.1±1.1 (15–18) m; two spherical polar capsules located anteriorly and conspicuously separated from each other, 4.8±0.3 (4.5–5.5) m in diameter; length of polar filament 59–61 m; coelozoic. S. argyrosomi n. sp. from Argyrosomus argentatus: monosporous plasmodium, (33–42) × (24–25) m; spore subspherical to spherical, with smooth surface and highly sinuous sutural line, 18.1±1.0 (17–20) × 19.8±1.3 (18–22) m; two spherical polar capsules located anteriorly and conspicuously separated from each other, 4.4±0.2 (4–5) m in diameter; length of polar filament 47–50 m; coelozoic. S. platycephali n. sp. from Platycephalus indicus: monosporous, disporous and polyporous plasmodia, 25–42 × 17–31 m; spore spherical with smooth surface and highly sinuous sutural line, 14.5±0.5 (14–15) m in diameter; two spherical polar capsules located anteriorly and conspicuously separated from each other, 4.3±0.2 (4–4.5) m in diameter; coelozoic.     

Determination of the apparent K mfor oxygen of Beneckea natriegens using the respirograph technique

The affinity for oxygen of the marine bacterium Beneckea natriegens was mesured using the Respirograph technique of Degn and Wohlrab. Values between 0.15 and 0.25 M oxygen were obtained for the apparent K _mfor oxygen regardless of the nature of the respiratory substrate. These values are an order of magnitude lower than those previously reported for B. natriegens using the conventional closed oxygen electrode system.     

Ongoing ultradian activity rhythms in the common vole,Microtus arvalis,during deprivations of food,water and rest

Summary The timing mechanism underlying ultradian (2–3 h) activity patterns in the common vole, Microtus arvalis, was studied using behavioural deprivation experiments. These were aimed at distinguishing between a homeostatic control mechanism, in which the rhythmic behaviour itself is part of the causal loop, and a clock mechanism, independent of the behaviour.In 175 experiments, deprivation of food during 3 ultradian cycles in (subjective) daytime did not result in significant changes in the ultradian periodicity of attempts to obtain the food, compared with ad lib. access to food and water. A minor, but significant increase in ultradian activity time () occurred in the course of the deprivation, but this was compensated by a shorter ultradian rest (). These results were obtained both in intact animals (n = 24), which showed ultradian and circadian rhythmicity in behaviour, and in animals (n = 21) with electrolytic lesions aimed at the suprachiasmatic nuclei (SCN), which lacked the circadian modulation of behaviour. Simultaneous deprivation of water and food in 8 voles without circadian rhythmicity during 40 experiments also did not lead to any change in the ultradian periodicity of feeding attempts.Rest deprivation was studied in 5 SCN lesioned voles, by forcing running wheel activity to continue following spontaneous running. Thus, the experimental activity bout was artificially lengthened to 2–9 h in 67 experiments. The onset of the subsequent rest episodes occurred independent of the duration of the preceding . The duration of was dependent on the preceding, experimental in a periodic fashion. The interval experimental (=lengthened +following ) was equal to one, two or three times the control (obtained on nonexperimental days). This result fits the prediction of a clock model and is in conflict with a monotonicincrease of with , as expected in a homeostatic, restorative process.It is concluded that the ultradian timing of activity in the common vole can be explained neither by homeostatic hunger or thirst mechanisms nor by homeostatic rest/activity regulation. The results strongly suggest an independent clock system generating ultradian feeding rhythms in the common vole.Abbreviations DD continuous darkness - LD light-dark regime - LL continuous light - RCA retrochiasmatic area - ARC arcuate nucleus - SCN suprachiasmatic nuclei - ultradian period - ultradian activity time - ultradian rest time     

Phylogenetic analysis of cytochromeb sequences in the dasyurid marsupial subfamily phascogalinae: Systematics and the evolution of reproductive strategies

We report DNA sequence variation in 861 bp of the mitochondrial cytochromeb gene from 10 species of the dasyurid marsupial subfamily Phascogalinae (including the New Guinean genusMurexia) and an outgroup planigale (Planigale ingrami). Phylogenetic analyses of these sequences indicate that (1) the subfamily consists of three major clades corresponding to (a)Phascogale, (b) AustralianAntechinus, and (c) New Guinean Antechinus andMurexia; (2) Antechinus habbema constitutes the earliest branch of the New Guinean clade; and (3); Antechinus melanurus and A. naso are sister species within the New Guinean clade. Among Australian antechnuses,A. stuartii andA. swainsonii are more closely related to each other than either is toA. flavipes, a result that is seemingly at odds with all previous systematic studies. Although resolution is limited, it appears thatAntechnius andMurexia species form a clade to the exclusion ofPhascogale. This relationship suggests that male semelparity is not a strong synapomorphy for Australian antechinuses and phascogales, despite its apparent physiological similarity in the two groups.To whom correspondence should be addressed.     

Observations on the reduction of non-activated carboxylates by Clostridium formicoaceticum with carbon monoxide or formate and the influence of various viologens

Crude extracts or supernatants of broken cells of Clostridium formicoaceticum reduce unbranched, branched, saturated and unsaturated carboxylates at the expense of carbon monoxide to the corresponding alcohols. The presence of viologens with redox potentials varying from E ₀=-295 to-650 mV decreased the rate of propionate reduction. The more the propionate reduction was diminished the more formate was formed from carbon monoxide. The lowest propionate reduction and highest formate formation was observed with methylviologen. The carbon-carbon double bond of E-2-methyl-butenoate was only hydrogenated when a viologen was present. Formate as electron donor led only in the presence of viologens to the formation of propanol from propionate. The reduction of propionate at the expense of a reduced viologen can be followed in cuvettes. With respect to propionate Michaelis Menten behavior was observed. Experiments are described which lead to the assumption that the carboxylates are reduced in a non-activated form. That would be new type of biological reduction.Non-standard abbreviations glc Gas liquid chromatography - HPLC high performance liquid chromatography - RP reverse phase; Mediators (the figures in parenthesis of the mediators are redox potentials E ₀ in mV) - CAV²⁺ carbamoylmethylviologen, 1,1-carbamoyl-4,4-dipyridinium dication (E ₀=-296 mV) - BV²⁺ benzylviologen, 1,1-dibenzyl-4,4-dipyridinium dication (E ₀=-360 mV) - MV methylviologen, 1,1-dimethyl-4,4-dipyridinium-dication (E ₀=-444 mV) - DMDQ²⁺ dimethyldiquat, 4,4-dimethyl-2,2-dipyridino-1,1-ethylendication (E ₀=-514 mV) - TMV²⁺ tetramethylviologen, 1,1,4,4-tetramethyl-4,4-dipyridinium dication (E ₀=-550 mV) - PDQ²⁺ propyldiquat, 2,2-dipyridino-1,1-propenyl dication (E ₀=-550 mV) - DMPDQ²⁺ dimethylpropyldiquat, 4,4-dimethyl-2,2-dipyridino-1,1-propenyl dication (E ₀=-656 mV) - PN productivity number=mmol product (obtained by the uptake of one pair of electrons) x (biocatalyst (dry weight) kg)^-1×h^-1     

Synthetic substrates in the histochemical demonstration of intestinal disaccharidases

Summary The splitting of 6-Br-2-naphthyl-, -naphthyl-, and 4-Cl-5-Br-3-indolyl-glycosides which proved useful for the assessment of cytological localization of intestinal enzymes in previous studies was investigated using isolated human and rat intestinal disaccharidases as a source of enzyme activities.Previous findings based on histochemical studies were confirmed and extended. 6-Br-2naphthyl-D-glucoside is cleaved by glucoamylase and sucrase-isomaltase. The participatio of trehalase in splitting of this substrate is very low and can be neglected. The mentioned -glucosidases are responsible for the brush border staining of enterocytes with this substrate when unfixed cold microtome sections are used. Even when a differential heat inactivation of sucrase-isomaltase and of glucoamylase occurs during paraffin embedding (so that the staining in paraffin sections is due mostly to glucoamylase) the use of natural substrates is desirable for a more precise assessment of sucrase-isomaltase activity (but without the possibility of a correct localization).4-Cl-5-Br-3-indolyl--D-fucoside is the substrate of choice for the demonstration of lactase. Even when this substrate is split also by hetero--galactosidase and by acid (lysosomal) -galactosidase these activities do not disturb the histochemical demonstration of lactase. If however some doubts arise, the inhibition with p-Cl-mercuribenzoate (2 · 10^–4 M) is to be emloyed (lactase activity is not inhibited). Due to a low K_m and a high V_max of indolyl-fucoside and due to its extreme stability in solution (which enables to use the substrate solution repeatidly) this substrate is suitable in routine practice even though it is expensive. -naphthyl- and 4-Cl-5-Br-3-indolyl--D-glucosides are split by lactase and -glucosidase. Due to the fact that the mutual delineation of these activities is not easy and that K_m an V_max for lactase are not so favourable as in the case of fucoside these substrates are not recommended for the assessment of lactase.6-Br-2-naphthyl--D-glucoside is the substrate of choice for the histochemical studies concerned with hetero--galactosidase and 4-Cl-5-Br-3-indolyl--D-galactoside for acid -galactosidase.     

LH-producing cells in the ovine pituitary

Summary An immunocytochemical technique using the peroxidase-antiperoxidase complex (PAP) was applied to identify and characterize the LH-secreting cells in the ovine pituitary at the ultrastructural level. These cells, round or oval in shape, possessing flattened cisternae of the rough endoplasmic reticulum, contain one class of secretory granules (mean diameter 250 nm) and large dense bodies (600 to 800 nm in diameter). LH molecules and the two subunits LH and LH were localized on the secretory granules and on the small granules near the Golgi complex. The large dense bodies, the cisternae of the endoplasmic reticulum and the saccules of the Golgi complex showed no reaction product.Abbreviations used in this Article O-LH ovine luteinizing hormone - b-LH bovine luteinizing hormone - p-LH porcine luteinizing hormone - p-LH porcine LH subunit - p-LH porcine LH subunit - O-FSH ovine follicle stimulating hormone - b-TSH bovine thyrotropic hormone - A-b LH antiserum to bovine LH - A-pLH antiserum to porcine LH subunit - A-pLH antiserum to porcine LH subunit     

Linkage relationships in the bovine MHC region. High recombination frequency between class II subregions

Class II genes of the bovine major histocompatibility complex (MHC) have been investigated by Southern blot analysis using human DNA probes. Previous studies revealed the presence of bovine DO , DQ , DQ , DR and DR genes, and restriction fragment length polymorphisms for each of these genes were documented. In the present study, the presence of three additional class II genes, designated DZ , DY , and DY , are reported. DZ was assumed to correspond to the human DZ gene while the other two were designated DY because their relationship to human class II genes could not be firmly established. The linkage relationships among bovine class II genes and two additional loci, TCP1B and C4, were investigated by family segregation analysis and analysis of linkage disequilibrium. The results clearly indicated that all these loci belong to the same linkage group. This linkage group is divided into two subregions separated by a fairly high recombination frequency. One region includes the C4, DQ , DQ , DR and DR loci and the other one is composed of the DO DY , DY , and TCPIB loci. No recombinant was observed within any of these subregions and there was a strong or fairly strong linkage disequilibrium between loci within groups. In contrast, as many as five recombinants among three different families were detected in the interval between these subregions giving a recombination frequency estimate of 0.17 ± 0.07. The fairly high recombination frequency observed between class 11 genes in cattle is strikingly different from the corresponding recombination estimates in man and mouse. The finding implies either a much larger molecular distance between some of the bovine class II genes or alternatively the presence of a recombinational hot spot in the bovine class II region.     

Genetic control of plastid carotenoids and transformation in the skin of Cucurbita pepo L. fruit

Summary The influence of allelic state of gene B on skin pigmentation in two cultivars of Cucurbita pepo L. has been studied. Total carotenoids were lower at early stages of fruit development in cultivar (cv.) Early Prolific (EP) BB YY fruit skin, than in EP B ⁺ B ⁺ YY fruit skin, but no differences were observed in total skin carotenoids twenty days after anthesis. Total carotenoids were lower in cv. Fordhook Zucchini (FZ) BB yy fruit skin, than in FZ B ⁺ B ⁺ yy fruit skin at all developmental stages from anthesis to maturity. Both green and yellow tissues contained typical foliar carotenoids. The carotenoids from yellow fruit skin of both EP genotypes and of FZ BB were characterized by a low carotene: xanthophyll ratio, with a high proportion of the xanthophylls esterified to fatty acids. The xanthophylls of the yellow tissues were esterified with 120, 140, 160 fatty acids. The carotenoids from the green fruit skin of FZ B ⁺ B ⁺ had a higher percentage of carotenes (primarily -carotene) and a lower percentage of esterified xanthophylls. Spectral shapes of carotenoid fractions from all yellow tissues were similar and distinguishable from those of green FZ B ⁺ B ⁺ tissue. The results of these studies are discussed in terms of the genetic control of plastid transformation in Cucurbita pepo L.New Jersey Agricultural Experiment Station No. D99201 (NE-9) 32-83, supported by state funds and funds from the Rutgers University Research Council     

Studies on the iodination of aras protein and the detection ofras polymers

Several methods for the iodination of recombinant v-H-ras protein were compared. The Iodobead method gave greates incorporation of radioactivity with minimal modification of theras protein. Upon treatment of theras protein with [¹²⁵I] Nal and an Iodobead, radioactivity was initially incorporated into a 22 kDa species with a pl of 5.2, then predominantly into a 23 kDa species with a pl of 5.4. The specific activity of [¹²⁵I]ras was 6×10⁶ cpm/pmol totalras protein. Iondination did not alter the biological activity of theras protein as judged by its ability to bind GTPS and induced maturation ofXenopus laevis oocytes. It is concluded that while iodination alters the apparent molecular weight and pI ofras, presumably by the oxidation of one or more classes of amino acids, this does not affect the biological function of the protein. Theras protein, radioactively-labelled with iodine using the Iodobead method, should be suitable for studies of protein-protein interactions involvingras. Treatment of iodinatedras with the chemical cross-linking agent disuccinimidyl suberate revealed the presence of several minor high molecular weight protein species. This result shows that, in a dilute solution of purifiedras protein, the monomeric form is in equilibrium with small amounts of polymeric forms.Abbreviations DSS Disuccinimidyl Suberate - GTPS Guanosine 5-[-thio] triphosphate - ATPS Adenosine 5[-thio] Triphosphate     

Effects of external phosphorus supply on internal phosphorus concentration and the initiation,growth and exudation of cluster roots in Hakea prostrata R.Br.

The response of internal phosphorus concentration, cluster-root initiation, and growth and carboxylate exudation to different external P supplies was investigated in Hakea prostrata R.Br. using a split-root design. After removal of most of the taproot, equal amounts of laterals were allowed to grow in two separate pots fastened together at the top, so that the separate root halves could be exposed to different conditions. Plants were grown for 10 weeks in this system; one root half was supplied with 1 M P while the other halves were supplied with 0, 1, 25 or 75 M P. Higher concentrations of P supplied to one root half significantly increased the P concentration of those roots and in the shoots. The P concentrations in root halves supplied with 1 M P were invariably low, regardless of the P concentration supplied to the other root half. Cluster root initiation was completely suppressed on root halves supplied with 25 or 75 M P, whereas it continued on the other halves supplied with 1 M P indicating that cluster-root initiation was regulated by local root P concentration. Cluster-root growth (dry mass increment) on root halves supplied with 1 M P was significantly reduced when the other half was either deprived of P or supplied with 25 or 75 M P. Cluster-root growth was favoured by a low shoot P status at a root P supply that was adequate for increased growth of roots and shoots without increased tissue P concentrations. The differences in cluster-root growth on root halves with the same P supply suggest that decreased cluster-root growth was systemically regulated. Carboxylate-exudation rates from cluster roots on root halves supplied with 1 M P were the same, whether the other root half was supplied with 1, 25 or 75 M P, but were approximately 30 times faster when the other half was deprived of P. Estimates of root P-uptake rates suggest a rather limited capacity for down-regulating P uptake when phosphate was readily available.     

Interaction between photosynthetic and respiratory electron-transfer chains in the membranes of Anabaena variabilis

The rate of CO₂- and p-benzoquione-dependent photosynthetic O₂ evolution by Anabaena variabilis cells remained unaltered and the rate of O₂ uptake observed after switching off the light (endogenous respiration) was enhanced by a factor of 6–8 when the O₂ concentration was increased from 200 to 400 M. Photosystem-I-linked O₂ uptake and respiration of the cells incubated with ascorbate and N,N,NN-tetramethyl-p-phenylenediamine was not appreciable influenced by the O₂ concentration. 2-Iodo-6-isopropyl-3-methyl-2,4,4-trinitrodiphenyl ether, blocking electron transfer at the plastoquinone level, suppressed O₂ evolution and had no influence on endogenous respiration. 2-n-Heptyl-4-hydroxyquinoline-N-oxide, an inhibitor of electron transfer between photosystems II and I, as well as the cytochrome-oxidase inhibitors N ₃ ^- , CN^- and NH₂OH, caused a 35–50% retardation of endogenous respiration and blocked photosynthetic O₂ evolution. The molar ratio of cytochromes b₆, f, c-553, aa₃ and photosystem-I reaction centers in the isolated membranes equalled approx. 2:1:2:0.7:2. It is inferred that endogenous respiration of A. variabilis cells is inhibited by the light-induced electron flow through both photosystems at the level of the plastoquinone-plastocyanin-oxidoreductase complex.Abbreviations DCMU 3-(3,4-dichlorophenyl)-1,1-dimethylurea - DNP-INT 2-iodo-6-isopropyl-3-methyl-2,4,4-trinitrodiphenyl ether - Hepes 4-(2-hydroxyethyl)-1-piperazine ethansulfonic acid - TMPD N,N,NN-tetramethyl-p-phenylenediamine     

Developmental morphology of the cyprinid fish Horadandia atukorali

Embryonic, larval, and juvenile development of a small Indian cyprinid, Horadandia atukorali, is described from laboratory-reared specimens. The eggs, measuring 0.7–0.8mm in diameter, were demersal, almost spherical in shape, transparent and unpigmented, with a pale yellow yolk without oil globules. Hatching occurred 47–54h after fertilization at 26.3–27.5°C. The newly hatched larvae, measuring 2.3–2.6mm in body length (BL) with 16+13=29 myomeres, had no melanophores, except on the eye, a single melanophore occurring on the lower margin, and xanthophores surrounding the pupil. The yolk was completely absorbed at 3.0mm BL. Notochord flexion was initiated at 4.0mm BL and finished at 4.4mm BL. Aggregate numbers of all fin rays were completed at 8.0mm BL. Squamation was initiated at 6.4mm BL and completed at 9.5mm BL. Although the eggs of Horadandia atukorali resembled those of other small danionin species, including Aphyocypris chinensis, Chela dadiburjori, Danio rerio, Devario malabaricus, and Hemigrammocypris rasborella, they differed from those of Danio rerio and Devario malabaricus in having a narrower perivitelline space. The larvae and juveniles of Horadandia atukorali were also similar to those of the latter five species in general morphology, especially in the presence of a melanophore on the lower margin of the eye at hatching, as in C. dadiburjori. However, the early life stage morphology of Horadandia atukorali differed from the other danionin species in having a conical yolk sac at hatching, no cement organ on the forehead in the yolk-sac larval stage, a divided gas bladder in the flexion larval stage, two dark lateral streaks on the head and chevron-like melanophores on the ventral body surface from the preflexion to postflexion larval stages, and xanthophores on the eyes at hatching.     

Investigations of carotenoids in some faunal elements of the Adriatic Sea. IV-molluscs

The carotenoids in the molluscsClanculus cruciatus, Patella coerulea, Mytilus galloprovincialis, Sepia officinalis andLoligo vulgaris from the Adriatic sea were investigated. Their presence was determined by means of columnar and thin-layer chromatography. The following carotenoids were found inC. cruciatus; mytiloxanthin-like, lutein, lutein ester, zeaxanthin and astaxanthin-like; inP. coerulea: mytiloxanthin-like, lutein, lutein ester, lutein-5,6-epoxide, zeaxanthin and astaxanthin-like; inM. galloprovincialis: -carotene, mytiloxanthin-like, lutein, lutein ester, lutein-5,6-epoxide and zeaxanthin; inS. officinalis: -carotene, lutein, lutein ester, tunaxanthin and zeaxanthin; inL. vulgaris: -carotene, -carotene, -carotene, -cryptoxanthin, isocryptoxanthin, isorenieratene, capsanthin, capsorubin, mutatochrome, triophaxanthin, zeaxanthin, 4-hydroxy--carotene and 4-keto--carotene     

Activation kinetics of single high-threshold calcium channels in the membrane of sensory neurons from mouse embryos

Summary Activation kinetics of single high-threshold inactivating (HTI orN-type) calcium channels of cultured dorsal root ganglion cells from mouse embryos was studied using a patchclamp method. Calcium channels displayed bursting activity. The open-time histogram was single exponential with an almost potential-independent mean open time _op. The closed-time histogram was multicomponent; at least three of the components were associated with the activation process. The fast exponential component with the potential-independent time constant _cl ^f included all intraburst gaps, while two slower ones with potential-dependent time constants _cl ^vs described shut times between bursts and between clusters of bursts. The burst length histogram was biexponential. The fast component with a relatively potential-independent time constant _bur ^f described short, isolated channel openings while the slow component characterized real bursts with a potential-dependent mean life time. The waiting-time histogram could be fitted by a difference of two exponentials with time constants being the same as _cl ^s and _cl ^vs . The data obtained were described in the frame of a 4-state sequential model of calcium channel activation, in which the first two stages are formally attributed to potential-dependent transmembrane transfer of two charged gating particles accompanying the channel transitions between three closed states, and the third one to fast conformational changes in channel protein leading to the opening of the channel. The rate constants for all transitions were defined. The validity of the proposed model for both low-threshold inactivating (LTI orT-type) and high-threshold noninactivating (HTN orL-type) calcium channels is discussed.     

Leaf flavonoid chemistry and the relationships of theLactoridaceae

Leaves of the monotypic angiosperm familyLactoridaceae exhibit flavonoid constituents consisting of six 3-0-diglycosides of the flavonols kaempferol and isorhamnetin. The presence of flavonols is concordant with the placement ofLactoridaceae among the archaic or primitive flowering plants. Flavonoid chemistry is less informative on the relationships of the family within the primitive dicots. The presence of isorhamnetin suggests closer affinities with families in theLaurales, particularly theGomortegaceae andMonimiaceae. Phenetic and cladistic analyses of morphological features place theLactoridaceae near several families in theMagnoliales.