Methods for determining ploidy in amphibians: Nucleolar number and erythrocyte size

Summary Diploid and triploidXenopus can be easily and reliably distinguished by the size of their erythrocytes. This method has several advantages over other methods, such as counting metaphase chromosomes and counting nucleoli. One problem with the latter method is the reduction in cells with a full complement of nucleoli when regenerating tissue is used.Research supported by NIH grant EY 01662.     

Differentiation in renal homografts of isolated parts of rat embryonic ectoderm

Summary The central and the peripheral areas of the head-fold stage rat embryo ectoderm develop into both the neural tissue and the epidermis when grafted under the kidney capsule of adult rats.This investigation was supported by the grant No. IV/3 from the Research Foundation of S.R. Croatia, and in part by NIH PL 480 Agreement No. 02-038-1.     

Isolation of filaments of the chick lens

Summary A preparation of intermediate filaments isolated from the chicken lens is enriched with a 50,000 dalton polypeptide.This study was supported by research grant EY 01417 of the National Institutes of Health, Bethesda, Maryland, USA.     

Methemoglobin formation and reduction in relation to hemoglobin oxygen affinity

Summary It is suggested that although the high oxygen affinity hemoglobin (Hb LR) (143(H21)HisGln) with stabilization of R quaternary conformation is not more susceptible to the oxidizing effect of nitrites in vitro, in an in vivo situation where hemoglobin is partly deoxygenated, it might be more susceptible to methemoglobin formation due to higher oxidation and lower reduction rate.Supported by NIH grant No. 5 RO1 AM 20181-02 and VA grant No. 5455-002.Acknowledgments. The technical assistance of Ms Carol A. Perry is highly appreciated.     

Cell fusion as a mechanism for the origin of polyploid cells in vitro

Zusammenfassung In Kulturen vonPeromyscus maniculatus und inMuntiacus muntjak wurden Tetraploidzellen gefunden, die als Produkte von Zellfusionen aufgefasst werden. Es wird angenommen, dass die ursprünglichen diploiden Elemente sich im Zeitpunkt der Fusion in verschiedenen Phasen des Zellzyklus befunden haben.

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Supported in part by NIH fellowship No. 1-F02-CA-42, 531-02 from the National Cancer Institute, USPHS grant No. GM-15361, and Grant No. E 286 from the American Cancer Society.     

Summing properties of the surround response mechanism of cat retinal ganglion cells

Summary Evidence is presented that, in the cat retina, the region in the visual field over which the surrounds of type X ganglion cells pool adaptive information corresponds to the region over which they pool signals.Acknowledgments. We wish to thank Mr O. Navarro for his valuable technical assistance. This research is supported by Public Health Service grant No. EY 00701.     

Histochemical demonstration of differences in AMP deaminase activity in rat skeletal muscle-fibres

Summary The histochemical method for AMP deaminase confirms that rat slow-twitch fibres contain less AMP deaminase activity than fast-twitch fibres. However, the enzyme appears similarly localized in all fibre types.This study was supported by NIH grant AM 21617.     

Spatial distribution of signal and adaptive sensitivity in the receptive field surrounds of cat retinal ganglion cells

Summary A comparison was made between adaptive and signal sensitivity profiles of the surround response mechanism of cat retinal ganglion cells. The 2 profiles were found to be similar for X cells but the surrounds of Y cells appear to pool adaptation over a smaller retinal region than they pool signals. Acknowledgments. We wish to thank Mr O. Navarro for his valuable technical assistance. This research is supported by Public Health Service grant No. EY 00701.     

The effect of chloroquine upon the developing lens

Summary Applied to the developing lens of the 14-day-old chick embryo, in organ culture conditions, chloquine prevented the elongation of the primary lens fibres, destroyed the equatorial ones and provoked vacuolisation and/or destruction in the epithelial cells.This work was supported by a grant from the office of the Chief Scientist, Ministry of Health, Israel     

Spectral properties of methemoglobins prepared by the action of sodium nitrite and potassium ferricyanide

Summary Methemoglobin was prepared by the addition of sodium nitrite or potassium ferricyanide to oxy or deoxyhemoglobin. The spectral properties of these methemoglobins were studied before and after extensive dialysis. It is shown that the methemoglobin formed by sodium nitrite has substantial spectral differences in visible and Soret band compared to that formed by potassium ferricyanide. These differences are proportional to the excess of sodium nitrite only. This suggests that both methemoglobins are similar compounds.Supported by NIH grant No. 5R01AM 20181-03 and VA grant No. 5455-003.Acknowledgments. The technical assistance of Ms Carol A. Perry and the secretarial assistance of Ms Wanda Stewart are highly appreciated.     

Effect of adapting target size on the gain of the surround response mechanism in X- and Y-cells in cat retina

Summary The adaptation field of the surround mechanism of X and Y retinal ganglion cells in the cat was assessed with variable size, unmodulated adapting spots. Both an on-inhibition measure and an off-discharge measure of surround gain was used. Results suggest that the surround mechanism in Y-cells is strongest in the receptive field middle but weak or nonexistent in the middle of X-cell receptive fields.Acknowledgment. This research was supported by Public Health Service grant No. EY 00701.     

Lysozyme levels in tissues of iron-deficient rats

Summary Rats were fed either diets sufficient (300 ppm) or insufficient (5 ppm) in iron for 10 weeks. The iron-deficient animals had lowered hemoglobin and hematocrit levels and higher levels of kidney lysozyme activity than did control animals. There were no significant changes in serum and spleen lysozyme activity levels.Supported in part by grant HL18712-02, Heart and Lung Institute, NIH.     

Ca2+ uptake and distribution in alloxan-diabetic rat arterial and venous smooth muscle

Summary This report demonstrates that in experimental diabetes mellitus (DM) calcium uptake and its distribution is altered in rat aortic but not in portal venous smooth muscle. Results are interpreted as consequences of increased calcium binding by aortic smooth muscle in experimental DM, which could account for the hyporeactivity of alloxan diabetic rat aorta reported previously.Supported by NIH grant No.HL-18015 and NIDA grant No. DA-02339.     

Spatial distribution of the adaptation field of the surround response mechanism in type X cat retinal ganglion cells

Summary The surround response mechanism in on-center X-cells in cat retina was found to be bimodally distributed and weak or nonexistent in the receptive field middle. An on-inhibition measure was used to assess surround mechanism gain.Acknowledgments. This research is supported by Public Health Service grant No. EY 00701.     

Lack of effect of colchicine on human neutrophil chemotaxis under agarose

Summary Human polymorphonuclear neutrophil chemotaxis under agarose was assessed following in vitro treatment of cells with colchicine. No inhibition of random migration or chemotaxis was detected. The discrepancy between these results and reports utilizing micropore filter assays could be due to the need for cell deformability in the latter.Supported by a grant from the Veterans Administration and Research grant AM 19349 from the NIAMDD, NIH.     

Distribution of cytoskeletal elements in cultured skin fibroblasts of patients with Duchenne's Muscular Dystrophy

Summary Cultured fibroblasts from patients suffering from Duchenne's Muscular Dystrophy were examined by indirect immunofluorescent techniques using antibodies against actin, myosin, tubulin, and intermediate-sized filaments. The cells display normal patterns of microfilamentous bundles (stress fibres), microtubules, and intermediate-sized filaments suggesting a normal organization of these cytoskeletal structures.Acknowledgments. This work was supported by the Swiss National Science Foundation, grant Nos 3.445-0.79 and 3.419.78.     

Visual responses in the central nervous system of the scallopPecten ziczac

Summary Electrical activity recorded from the lateral lobe of the visceroparietal ganglion in the scallop Pecten ziczac reflects predominatly the visual response to onset of light stimulation, suggesting that shadow reflex mechanisms likely occur elsewhere within the central nervous system.We thank Wolfgang Sterrer and the Bermude Biological Station for their cooperation and the use of their facilities. Support was, in part, from an NSF grant to the BBS (PCM 76.13459) and from an NIH grant (NS 12971). This paper is a contribution from the Bermuda Biological Station (No. 708) and the Tallahassee, Sopchoppy and Gulf Coast Marine Biological Association (No. 84).     

Migration of lymphocytes through the endothelium of venules in experimental allergic neuritis

Zusammenfassung Bei der experimentellen allergischen Neuritis verlassen die Lymphozyten das zirkulierende Blut der Venolen der peripheren Nerven, indem sie eher durch die als zwischen den Endothelzellen austreten. Der Durchtritt durch das Zytoplasma der Endothelzellen ist ein Beispiel von Emperipolesis.

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Supported by parts by NIH grant No. NB-03789-05, Inst. grant No. FRO5486-04, and a grant from the Swedish Medical Research Council. I thank Mr.L. Cherkas for help with the photography.     

Ethanol reduces Ca2+ concentrations in arterial and venous smooth muscle

Summary The present results, using isolated rat aortic strips and portal vein segments, demonstrate that ethanol (170–430 mM) significantly inhibits calcium uptake in these 2 different types of vascular smooth muscle.Supported by NIH grant No. HL-18015 and NIMH grant No. MH-26236. Request for reprints should be addressed to B.M. Altura.     

Influence of pinealectomy on serum estrogen and progesterone levels in blind-anosmic female rats

Summary Previous studies show that the suppression of gonadal function in blind-anosmic rats is dependent on the pineal gland. The present results demonstrate that in young female rats both the pineal gland and dual sensory deprivation have additional independent antigonaldal effects.This work was partially supported by state institutional funds and by NSF grant No. PCM 74-06276-276-A02. The radioimmunoassays of the steroids were carried out with the aid of the Radioimmunoassay Core which is supported by USPHS grant No. 1T30 HD-10202. We also thank Constance Stahl for typing assistance.