Czechoslovak Academy of Sciences

About: Czechoslovak Academy of Sciences is a based out in . It is known for research contribution in the topics: Catalysis & Adsorption. The organization has 13227 authors who have published 17335 publications receiving 272882 citations.

The development of Pacinian corpuscles.

Abstract: The fine structural development of Pacinian corpuscles on the interosseous membrane of the rat was investigated from day 18 of gestation until 2 months after birth. At the initial stage of development on day 19–20 of gestation, Pacinian corpuscles consist of a cylindrical sensory terminal surrounded by one layer of cells which are apposed to the terminal and send off short lamellar processes towards the axolemma. These presumptive inner core cells accumulate around the terminal in continuation of the Schwann cell sheath, which indicates their Schwann cell origin. Both the inner core cells and their lamellae rapidly increase in number. At birth, the sensory terminal is already enclosed in a rudimentary inner core comprising several layers of loosely arranged lamellae, with cell nuclei accumulated at the outer circumference of the inner core. The sensory terminal sends off axonal processes from random sites on its circumference, and ends as a bulb which projects numerous axonal processes in all directions. The organelle content of the terminal consists of many mitochondria oriented lengthwise among microtubules and neurofilaments; clear and dense core vesicles are found in groups beneath the axolemma and at the bases of axonal processes and branches, whereas the processes themselves contain a microfilamentous network. Numerous coated invaginations and vesicles are found at the axolemma and in the lamellae enclosing the axon, indicating uptake of macromolecules on both sides of the periaxonal cleft. The outer capsule begins to form around the inner core shortly before birth; in neonatal rats, it consists of approximately five attenuated lamellae. During the first postnatal week, the inner core lamellae increase in number, become tightly packed together and concentrically arranged. The bilateral symmetry of the inner core is established 5–12 days after birth, when 2 opposite radial clefts are formed, bisecting the inner core cylinder into 2 corresponding sectors. From the cellular layer of the inner core, cytoplasmic arms penetrate through the radial cleft, giving rise to hemilamellae of one or both sectors. The axonal processes eventually become aligned 2–3 weeks after birth so that they project into the radial clefts, except for the bulbous ultraterminal part from which they project in all directions. During the 2 postnatal months studied, the inner core grows continuously in length, but its diameter remains practically unchanged. The outer capsule grows considerably during this time, as both the number of capsular layers and the spacing between them continue to increase. Pacinian corpuscles are on the average 475.8 ± 10.7 μm in length and 220.8 ± 6.3μm in diameter by day 60 postnatal, their size having increased about four fold from birth.

Solution properties of drug carriers based on poly[N‐(2‐hydroxypropyl)methacrylamide] containing biodegradable bonds

Abstract: The solution properties of water-soluble drug carriers based on copolymers of N-(2-hydroxypropyl)methacrylamide containing p-nitroaniline (drug model) attached to the copolymer by enzymatically degradable oligopeptide chains, were studied using light scattering, GPC and sedimentation methods. It was found that these polymers associate in water forming micelles with p-nitroaniline being inside and hydrophilic polymer chains outside. The association number and compactness of micelles both depend on the content of hydrophobic side chains, polymer concentration and temperature. Micellar shells hinder the penetration of enzymes into the micellar core, thus reducing the rate of enzyme-catalyzed release of p-nitroaniline.

Termination of adult diapause in pyrrhocoris apterus (heteroptera: pyrrhocoridae) in the field

Abstract: The time when diapause ends in the Czech populations of Pyrrhocoris apterus was studied by the transfer of the overwintering bugs to laboratory conditions of 25°C and long day (L 18, D 6) or short day (L 12, D 12). Both the incidence of oviposition after the transfer to short-day conditions and the duration of the pre-oviposition period after the transfer to long-day conditions indicate that the diapause ends in the period of December–January. Development is then inhibited environmentally, by low temperatures. Thus the diapause of P. apterus is terminated before the advent of hard frosts. The resistance to frost is not bound to the condition of the intrinsic inhibition of the maturation of gonads. Zusammenfassung DIE TERMINATION DER IMAGINALDIAPAUSE BEI PYRRHOCORIS APTERUS (HETEROPTERA: PYRRHOCORIDAE) IM FREIEN Die Termination der Diapause kann nicht — wie vielfach angenommen wird — mit der Wiederaufnahme der Entwicklung gleichgesetzt werden, da in der Natur die Entwicklung nach dem Ende der Diapause meist durch niedrige Temperaturen noch weiterhin inhibiert bleibt (Quieszenz). Um das wahre Ende der Diapause bei Pyrrhocoris apterus zu ermitteln, wurden Wanzen im Verlaufe der Uberwinterung (Hibernation) (August—Marz) in abgestuften Intervallen aus dem Freien ins Laboratorium ubertragen, wo 25° und 24-stundige Photoperioden mit Photophasen von 12 oder 18 Std herrschten. Die Versuche wurden wahrend drei Winterperioden durchgefuhrt (1964–65, 1966–67, 1967–68) und dabei Wanzen aus drei klimatisch unterschiedlichen Lokalitaten: Smolenice, Slaný und Jankovice (Seehohe 240, 280 bzw. 430 m) verglichen, deren mittlere Jahrestemperatur 9,0, 8,2 bzw. 7,5° betragt. Die Wanzen wurden paarweise bei Lindensamen und Wasser gehalten. In allen Versuchen wurde Eiablage, bei manchen auch Kopulation, Eianzahl und Schlupfrate, taglich ermittelt. Im Langtag (L 18, D 6) begannen die Weibchen stets Eier zu legen, doch verkurzte sich im Verlaufe der Uberwinterung schrittweise die Lange der Praovipositionsperiode. Zwischen August und Anfang Oktober begannen die Eiablagen in der Regel nach 26–34 Tagen. Nach Mitte Januar (manchmal auch schon ab Dezember) verkurzte sich die Praovipositionsperiode auf nur 8–9 Tage, was dem Wert der Praovipositionszeit bei Nondiapause-Tieren entspricht. Im Kurztag (L 12, D 12) blieben die diapausierenden Wanzen unfruchtbar. Die Weibchen der August- und September-Proben legten uberhaupt keine Eier (obwohl sie zwei uber drei Monate lang gehalten wurden. Die Weibchen der im Oktober und November eingeholten Proben legten nur zu einem geringen Prozentsatz (14 bzw. 32%) und nach langerer Praovipositionsperiode ab. Bereits ab Mitte Dezember legten jedoch alle Weibchen nach einer Praovipositionsperiode von nur 8–11 Tagen ab. In der Natur endet also die imaginale Diapause bei tschechischen Populationen von P. apterus schon im Dezember, gegebenenfalls im Januar, d.h. noch vor Eintritt strengerer Froste. Der Adaptationswert der Diapause beruht daher nicht auf einer direkten Erhohung der Frostresistenz, sondern auf der Synchronisation des Lebenszyklus der Insekten mit der Jahreszeit. Die photoperiodische Termination der imaginalen Diapause bei P. apterus wird mit ahnlichen Erscheinungen bei anderen Insektenarten verglichen.

Dislocation structure and applied, effective and internal stress in high-temperature creep of alpha iron

Abstract: The dislocation structure of alpha iron formed in high-temperature creep mas investigated in the transmission electron microscope and its quantitative characteristics—dislocation density, subgrain diameter and subgrain misorientation—were measured in the primary as well as in the steady-state creep. The steady state substructure characteristics are correlated with the steady state values of the applied, effective and internal stress and the development of the substructure in the primary creep is discussed. The results of the structure observation correspond well to the macroscopic creep data (Pahutora, Orlova, Kuchařova, Cadek, to be published).