Metabolic biochemistry and the making of a mesopelagic mammal

Large seals such as northern and southern elephant seals and Weddell seals are able to dive for startling duration and enormous depth. The current dive duration record is 120 minutes (recorded for the southern elephant seal); the current depth record is 1.5 km (recorded for the northern elephant seal). Equally striking is the widespread observation that these seals when at sea spend close to 90% of the time submerged and often at great depth. For practical purposes, these species can be viewed as true mesopelagic animals when they are at sea. A review of current knowledge indicates that low power output but high efficiency metabolic functions of skeletal muscles coupled with inherently low (and potentially further suppressible) metabolic rates constitute strategic biochemical components in the making of a mesopelagic mammal.     

Metabolic biochemistry and the making of a mesopelagic mammal.

Large seals such as northern and southern elephant seals and Weddell seals are able to dive for startling duration and enormous depth. The current dive duration record is 120 minutes (recorded for the southern elephant seal); the current depth record is 1.5 km (recorded for the northern elephant seal). Equally striking is the widespread observation that these seals when at sea spend close to 90% of the time submerged and often at great depth. For practical purposes, these species can be viewed as true mesopelagic animals when they are at sea. A review of current knowledge indicates that low power output but high efficiency metabolic functions of skeletal muscles coupled with inherently low (and potentially further suppressible) metabolic rates constitute strategic biochemical components in the 'making' of a mesopelagic mammal.     

Suppression by LH-releasing hormone (LHRH) of the augmenting effect of estradiol on the secretion of LH and FSH by the rat pituitary gland

Summary Estradiol sensitizes the pituitary gland for the gonadotropin-releasing activity of LHRH. LHRH desensitizes the pituitary gland and does so in a dose-dependent manner. Moreover, LHRH dose-dependently suppresses the sensitizing effect of EB. In rats with an LHRH concentration in the plasma of about 90 pg/ml, the sensitizing effect of estradiol is absent.     

Suppression by LH-releasing hormone (LHRH) of the augmenting effect of estradiol on the secretion of LH and FSH by the rat pituitary gland

Estradiol sensitizes the pituitary gland for the gonadotropin-releasing activity of LHRH. LHRH desensitizes the pituitary gland and does so in a dose-dependent manner. Moreover, LHRH dose-dependently suppresses the sensitizing effect of EB. In rats with an LHRH concentration in the plasma of about 90 pg/ml, the sensitizing effect of estradiol is absent.     

Inhibition and stimulation by 5-bromodeoxyuridine of erythropoiesis by chick blood island cells

Summary Erythropoiesis in liquid cultures of cell populations resolved from chick blastodiscs at the primitive streak and head-fold stages was totally inhibited by 5–8 g/ml of 5-bromodeoxyuridine. However, concentrations of 0.2 /ml of the nucleoside enhanced the number of erythroid cells formed.This work was supported by grants from the Medical Research Council and National Research Council of Canada. We thank MissesK. Beall andN. N. McGrath for technical assistance. S. D. W. is an Associate of the Medical Research Council.     

β-Endorphin in normozoospermic and pathologic human semen

Summary -Endorphin was estimated in normozoospermic, oligozoospermic and azoospermic human semen. The mean amount in normozoospermic specimens was 278.6±43.6 (SE) pg/ml while in the others only 191.1±25 pg/ml. Both values are significantly higher than those present in the blood.     

Beta-endorphin in normozoospermic and pathologic human semen

beta-Endorphin was estimated in normozoospermic, oligozoospermic and azoospermic human semen. The mean amount in normozoospermic specimens was 278.6 +/- 43.6 (SE) pg/ml while in the others only 191.1 +/- 25 pg/ml. Both values are significantly higher than those present in the blood.     

Genome and cell sizes in frogs: A comparison with salamanders

Summary The nuclear volume (Nv), cell volume (Cv) and cell surface area (Cs) of erythrocytes from 26 anuran species show a linear and direct correlation with the nuclear DNA content; the Cs/Cv ratio tends to decrease as DNA increases. Analogous phenomena are found in urodeles possessing less than 70 pg/N of DNA, whereas in those with a larger genome there is a trend towards stabilization of the Cs/Cv ratio. The same mechanisms appear to control the ratios of genome sizes to cell sizes within the amphibians and possibly in other vertebrates as well. The former, however, seem to avail themselves to a greater extent of the adaptive properties inherent in their genome and cell size variations.Research supported by a grant from the Italian CNR.     

Testosterone in human saliva

Summary Testosterone has been detected in whole human saliva. Levels averaged (±SE) 295±36 and 195±25 pg/ml in adult males and females, respectively, and usually were undetectable in children. In adult males, the excretion of testosterone in saliva appeared to follow a circadian rhythm.Acknowledgments. This study was supported by grant No. MA-4454 from the Medical Research Council of Canada. The authors wish to thank Mr.D. B. Beaton for excellent technical assistance.     

Aplysianin-A,an antibacterial and antineoplastic glycoprotein in the albumen gland of a sea hare,Aplysia kurodai

Summary Aplysianin-A, an antibacterial and antineoplastic factor in the albumen gland of the sea hareAplysia kurodai, was isolated. It had a molecular weight of approximately 320 kD and consisted of subunits with a molecular weight of 85 kD. It contained 9.8% neutral sugar. Aplysianin A showed 50% inhibition ofBacillus subtilis growth at a concentration of 4 g protein/ml and 50% lysis of murine MM46 tumor cells at 14 ng protein/ml. A partial identity of antigenic specificity of the purified specimen with an antineoplastic factor fromAplysia eggs was observed in immunodiffusion tests.Acknowledgment. We are indebted to the staff of Fisheries Research Laboratory, Faculty of Agriculture, University of Tokyo, Maisaka, for the collection of sea hares.     

Rate-compensated synaptic events in antarctic fish: Consequences of homeoviscous cold-adaptation

Summary At ambient sub-zero temperatures, muscles from antarctic fish produce spontaneous postsynaptic currents (MEPCs) of significantly shorter duration than those of temperate fishes. Fast decay of antarctic MEPCs is a predictable consequence of the increased membrane fluidity attributable to fatty acid unsaturation in cold-adapted animals.We wish to thank the Antarctic Division of the New Zealand Department of Scientific and Industrial Research, and the staff of Scott Base, without whom this work could not have been done. The work was supported financially by grants from the New Zealand University Grants Committee and from the Auckland University Research Committee. We are also grateful to members of the United States Antarctic Research Program, in particular Dr A. L. DeVries, for advice and assistance.     

Titers of ecdysone, 20-hydroxyecdysone and juvenile hormone III throughout the life cycle of a hemimetabolous insect,the ovoviviparous cockroachNauphoeta cinerea

Summary Titers of ecdysone, 20-hydroxyecdysone and juvenile hormone III were measured in whole body extracts or hemolymph of embryos, first, penultimate and last stadium nymphs, and adult females ofNaupoheta cinerea. We used a gas-chromatography/mass spectrometry method for quantifying juvenile hormone and a radio-immunoassay for ecdysteroid determination. Juvenile hormone III is particularly abundant in the embryonic stage (up to 960 ng/g), at a low level in first and penultimate stadium nymphs (2–10 ng/ml) and almost absent in the last nymphal stadium; in the adult female the juvenile hormone titer rises to 180 ng/ml in hemolymph during rapid oocyte growth. The titers of ecdysone and 20-hydroxyecdysone undergo similar fluctuations in the embryonic and nymphal stages, being highest at the time of cuticle formation in the embryo and a few days before the nymphal and adult molts (around 100–200 ng/ml for exdysone and 2–4 g/ml for 20-hydroxyecdysone).Acknowledgments. We thank Mrs A. Tschan for rearing the cockroaches, Mr M. Kaltenrieder for drawing the graphs, Mr G.C. Jamieson and Mrs C. Reuter for GC/MS analyses. We are also grateful to the Swiss National Science Foundation (grant no. 3.291-0.82 to B. Lanzrein) and the United States National Science Foundation (grant no. PCM 82-08665 to D.A. Schooley) for their financial support.     

Effects of an insect growth regulator,ZR-2646 on egg fertility in the fleshfly,Sarcophaga bullata

Summary Topical application of an insect growth regulator, ZR-2646 on adult females ofSarcophaga bullata affects the viability of the eggs. The compound is most effective if applied at the time of ovulation.The work was supported by the National Research Council of Canada.I am grateful to Dr G.B. Staal, Zoecon Corporation, Palo Alto, California, for the gift of ZR-2646.     

Cold tolerance of two Antarctic terrestrial arthropods

Summary Two Antarctic arthropods,Alaskozetes antarcticus (Acari) andCryptopygus antarcticus (Collembola) possess the ability to supercool to –30°C, but the realisation of this potential is dependent on starvation. The mite contains glycerol in a concentration of about 1% fresh weight.Acknowledgments. We thank the British Antarctic Survey, Cambridge and the Zoological Institute. University of Oslo for support and reasearch facilities, and the Natural Environment Research Council for a research grant (GR. 3/2797). We are grateful to Ms I. Tambs-Lyche for technical assistance.     

Human growth hormone in urine: development of an ultrasensitive radiometric assay

An immunoradiometric assay for human growth hormone (HGH) has been developed which has a detection limit of 1 ng/l and can measure HGH in unextracted urine from normal children and adults. The assay is based on a two-step procedure, using a solid-phase goat-anti-HGH immunosorbent for immunoextraction and [125I]-labeled monoclonal HGH-antibody for detection and quantification. The assay is not affected by urea, NaCl or changes of pH from 5-8. The mean urine HGH concentration in normal children is 6.78 +/- 7.6 (SD) pg/ml, in patients with HGH-deficiency 1.3 +/- 0.9 pg/ml which increases to 11.7 +/- 13.4 pg/ml on the day of growth hormone injection.     

Relationship between the pars intermedia and the pars nervosa in the hypophysis of an antarctic seal

Resumen La pars intermedia de la hipófisis de la foca de Weddell (Leptonychotes weddelli) presenta trabéculas que irrumpen en la Pars nervosa. En estas trabéculas epiteliales se encuentran grumos y fibras de materialGömöri positivo. Este material no fué hallado en ninguna otra región de la adenohipófisis.

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This work has been carried out at the Scientific Station Almirante Brown in Antarctica during the Antarctic year 1966. It was supported by the Instituto Antártico Argentino. Contribución del Instituto Antártico Argentino No. 120.     

Melatonin in the plasma of growing sheep subjected to short and skeleton long photoperiods

Summary The levels of melatonin in plasma were measured at hourly intervals for 24 h in 8 sheep, 4 under 8L:16D (short day) and 4 under 7L:10D:1L:6D (skeleton long day) after 38 days of exposure. Mean concentrations did not differ significantly between treatments (52 pg/ml under short days; 91 pg/ml for skeleton long days), but the levels were more stable during 24 h in the SD treatment. Under skeleton long days there were 3 peaks during the 10D scotophase, with low levels during the 6D scotophase and the 7L photophase.     

Ecdysteroids: possible candidates for the hormone which triggers salivary gland degeneration in the ixodid tickAmblyomma hebraeum

Summary Following engorgement, female ixodid ticks secrete a tick salivary gland degeneration factor (TSGDF) into the hemolymph. Here we show that the arthropod ecdysteroid hormones, ecdysome and 20-hydroxyecdysone, induce degeneration of tick salivary glands maintained in organ culture. The effective dose range in vitro is 30–300 ng/ml, a range reported to be physiological for this species following repletion. In addition, infusion of 20-hydroxyecdysome in vivo induces salivary gland degeneration. We therefore propose that TSGDF may be an ecdysteroid.Acknowledgments. Some of the data reported here were presented to the annual meeting of the Canadian Society of Zoologists, 15–18 May 1983; Program of abstracts, page 53. Financial support of the Canadian National Sportsmen's Fund and NSERC Canada to W.R.K. is gratefully acknowledged.     

Predominant expression of σ and ε globin genes in human leukemia K-562(S6) variant cell line

Summary In the human leukemia K-562(S6) cell line (a) the accumulation ofa-globin chains is low or absent, (b) -globin gene expression is correlated with expression of -chains and (c) the genes responsible for the terminal cell division are not operated within 8–12 cell cycles, while K-562 (S6) cells are fully induced to erythroid differentiation.This work was supported by grants from the Italian National Research Council (C.N.R.) G. R. is a recipient of a fellowship from the National Committee for Nuclear Energy, Rome. Address for reprint requests: R. G., Centro di Studi Biochimici, Via L. Borsari 46, I-44100 Ferrara.     

Functional subdivision within a lobster motor unit

Summary A discrete middle band of tonic fibers in the claw closer muscles of lobsters functions as a sub-unit of the slow motor unit in maintaining dactyl posture at a low frequency of firing due to its synaptic properties and strategic location.Supported by National Institute of Health Grant to Dr A. G. Humes and the late Fred Lang.Supported by National Sciences and Engineering Research Council and Muscular Dystrophy Association of Canada.