Physiological Investigations on Restrictions to Transport of Sucrose in Ears of Wheat

1976 ◽  
Vol 3 (3) ◽  
pp. 337 ◽  
Author(s):  
CF Jenner
Keyword(s):  
Grain Growth ◽  
Water Transport ◽  
The Other ◽  
Metabolic Inhibitors ◽  
External Concentration ◽  
Transpiration Stream ◽  
Other Hand ◽  
Sieve Tubes

Accumulation of sucrose in glumes and pales of detached ears of wheat cultured on solutions of sucrose is directly dependent on external concentration; compared with the external level, sugar builds up to higher levels inside these organs, and the uptake of sugar is not reduced much by metabolic inhibitors. In contrast, influx of sucrose into the grains is saturated at relatively low (external) levels of sucrose; the concentration within the grains is lower than in the supplying solution, and movement into the grains is very sensitive to the action of metabolic inhibitors. Sucrose enters the cultured ear in the transpiration stream and its build-up in the structures enclosing the grain is due to the evaporation of water. Transport to the grain, on the other hand, is dependent upon translocation in the phloem. It is suggested that the passage of sucrose to the grain is restricted by processes involved in transfer from xylem to phloem, or by translocation within the sieve tubes, or both. It is postulated that similar limitations operate on the transport of sucrose derived from normal assimilation. The detached-ear technique may be of value as a method of estimating the scale of limitations to grain growth conferred by the supply of assimilates to the grain.

scholarly journals Effects of anaerobiosis and inhibitors on O2-production by human granulocytes

Blood ◽  
1975 ◽  
Vol 45 (6) ◽  
pp. 851-861 ◽  
Author(s):  
JT Curnutte ◽  
BM Babior
Keyword(s):  
Cell Motility ◽  
Cytochalasin B ◽  
The Other ◽  
Metabolic Inhibitors ◽  
Antimycin A ◽  
Sulfhydryl Reagents ◽  
Other Hand ◽  
Human Granulocytes ◽  
O2 Production ◽  
Microtubule Function

Abstract A study was carried out on the effect of a number of inhibitors as well as of anaerobiosis on the production of superoxide (O2 minus) by human granulocytes. Several metabolic inhibitors, including bazide, cyanide, antimycin A, and 2,4-dinitrophenol had no effect on O2 minus production. Methimazole, which inhibits myeloperoxidase, was also without effect. The sulfhydryl reagents N-ethylmalemide and iodoacetamide greatly inhibited O2 minus production. O2 minus production did not take place under N2. Agents that affect cell motility were also examined. Colchicine and vinblastine, alkaloids which affect microtubule function, had little effect on granulycote O2 minus production. On the other hand, cytochalasin B, a fungal antimetabolite thought to affect microfilaments, inhibited O2 minus production by resting granulocytes and stimulated its production by cells incubated with bacteria. The mechanism and significance of this effect remain to be elucidated.

Influence of Liquid Phase on Grain Growth of Ba0.998La0.002TiO3 Ceramics

2008 ◽  
Vol 368-372 ◽  
pp. 461-464
Author(s):  
Yong Ping Pu ◽  
Gong An Yang ◽  
Yun He Liang ◽  
Wen Hu Yang ◽  
Jin Fei Wang
Keyword(s):  
Liquid Phase ◽  
Grain Growth ◽  
The Other ◽  
Other Hand ◽  
Liquid Phases

The influence of liquid phase on grain growth of Ba0.998La0.002TiO3+xmol%TiO2 (x=0~5.0) ceramics sintered at 1350°C was investigated. The result showed that the liquid phase must present during grain growth; on the other hand, BaTiO3 grains must be dissolved, and then, precipitated from the liquid phase during the process of dissolution-precipitation. Otherwise, the grain growth was inhibited. The liquid phases of Ba6Ti17O4 and Ba2TiSi2O8 promoted grain growth due to high solution of BaTiO3 grains in the liquid phases. Ba2Ti2SiP2O13 liquid phase inhibited grain growth since BaTiO3 grains cannot dissolve into the phase, consequently the samples showed insulating behaviour.

Ultrastructural analysis of the midgut of Drosophila auraria larvae. Morphological observations and their physiological implications

1984 ◽  
Vol 62 (4) ◽  
pp. 659-669 ◽  
Author(s):  
V. K. Dimltriadis ◽  
C. D. Kastritsis
Keyword(s):  
Plasma Membrane ◽  
Water Transport ◽  
Ultrastructural Analysis ◽  
The Other ◽  
Morphological Data ◽  
Stages Of Development ◽  
Central Lumen ◽  
Other Hand ◽  
Basal Plasma Membrane ◽  
Basal Plasma

Electron and light microscopic examinations of Drosophila auraria larval midguts derived from insects of various stages of development show six clearly differentiated regions along its monolayered epithelium. Generally, the morphological data indicate that the cells of all these regions are involved in the elaboration and secretion of products in a manner that appears to follow the generally accepted scheme for these events. Among the six regions, the posterior and the anterior sections of the midgut are the regions that could be considered as the first and second most important sites, respectively, for terminal digestion and the absorption of nutrients. The middle midgut, on the other hand, in which long infoldings of the basal plasma membrane of the cells are observed, can be considered as a region of intense water transport between the hemolymph and the central lumen of the midgut.

Study of acute pharmacologic effects of prolactin on calcium and water transport in the rat colon by an in vivo perfusion technique

2001 ◽  
Vol 79 (5) ◽  
pp. 415-421 ◽  
Author(s):  
Nateetip Krishnamra ◽  
Jiraporn Ousingsawat ◽  
Liangchai Limlomwongse
Keyword(s):  
Water Absorption ◽  
Water Transport ◽  
The Other ◽  
Rat Colon ◽  
Perfusion Technique ◽  
Perfusion Rate ◽  
Calcium Fluxes ◽  
Other Hand ◽  
Water Secretion

We investigated the acute effect of intraperitoneally administered prolactin on calcium and water transport in colon of sexually mature female Wistar rats using an in vivo perfusion technique. Test solution containing (in mM) NaCl, 100; KCl, 4.7; MgSO4, 1.2; CaCl2, 20; D-glucose, 11; sodium ferrocyanide (Na4Fe(CN)6), an index of net water transport, 20; and 0.7 (µCi 45CaCl2 (1 Ci = 37 GBq) was perfused througth the 8-cm colonic loop for 60 min at perfusion rates of 0.5 or 1.0 mL·min–1. Calcium and water transport was also studied under a no flow condition to stimulate the condition often found in the colon by in vivo ligated colonic loop for 30 min. Control results showed no correlation between calcium transport and water flux. Flow of luminal solution at 0.5 and 1.0 mL·min–1 was found to reverse net calcium absorption from 0.04 ± 0.01 nmol·g–1 dry weight·h–1 to net calcium secretion of 0.04 ± 0.04 and 0.9 ± 0.02 nmol·g–1 dry weight·h–1, respectively. Neither 0.4, 0.6, nor 1.0 mg·kg–1 prolactin had any effect on calcium fluxes in the colon. On the other hand, at a perfusion rate of 1 mL·min–1, 0.4 mg·kg–1 prolactin significantly decreased net water absorption from 3.86 ± 0.90 to 0.88 ± 0.64 mL·g–1 dry weight·h–1 (P < 0.001), and the higher doses of 0.6 and 1.0 mg·kg–1 prolactin reversed net water absorption to net water secretion of 2.20 ± 0.63 and 2.33 ± 0.89 mL·g–1 dry weight·h–1, respectively (P < 0.001). The stimulatory effect of prolactin on water transport was completely abolished by reducing the perfusion rate from 1.0 mL·min–1 to zero. The stimulatory effect of prolactin on water secretion at perfusion rate of 1.0 mL·min–1 was also abolished when luminal [Na+] was reduced from 180 to 80 mM. We concluded that, unlike in the small intestine, calcium fluxes in the colon are not related to water transport and did not respond at all to prolactin. Water transport, on the other hand, was reversed from net absorption to secretion by prolactin. We propose that this prolactin-induced water secretion is probably mediated by recycling of luminal sodium in the vicinity of tight junctions.Key words: calcium fluxes, colon, perfusion technique, prolactin, water transport.

Über die Beziehungen der RNS- und Proteinsynthese zum Zellkern in Siebzellen von Vicia faba

1964 ◽  
Vol 19 (11) ◽  
pp. 1066-1071 ◽  
Author(s):  
Stefanie Neumann ◽  
Reinhold Wollgiehn
Keyword(s):  
Vicia Faba ◽  
Rna Synthesis ◽  
The Other ◽  
Other Hand ◽  
Cytoplasmic Rna ◽  
Nuclear Rna ◽  
Sieve Tubes

Autoradiographic investigations on the dependency of the RNA and protein syntheses on the nucleus have been carried out in sieve tubes of Vicia faba.In young nucleated sieve tubes 3H-uridine is incorporated primarily into the nuclear RNA and later into the cytoplasmic RNA. In sieve tubes with degenerated nuclei no incorporation of uridine in RNA takes place. On the other hand, 3H-phenylalanine is incorporated also into the proteins of old sieve tubes without RNA synthesis.

scholarly journals Effects of anaerobiosis and inhibitors on O2-production by human granulocytes

Blood ◽  
1975 ◽  
Vol 45 (6) ◽  
pp. 851-861 ◽  
Author(s):  
JT Curnutte ◽  
BM Babior
Keyword(s):  
Cell Motility ◽  
Cytochalasin B ◽  
The Other ◽  
Metabolic Inhibitors ◽  
Antimycin A ◽  
Sulfhydryl Reagents ◽  
Other Hand ◽  
Human Granulocytes ◽  
O2 Production ◽  
Microtubule Function

A study was carried out on the effect of a number of inhibitors as well as of anaerobiosis on the production of superoxide (O2 minus) by human granulocytes. Several metabolic inhibitors, including bazide, cyanide, antimycin A, and 2,4-dinitrophenol had no effect on O2 minus production. Methimazole, which inhibits myeloperoxidase, was also without effect. The sulfhydryl reagents N-ethylmalemide and iodoacetamide greatly inhibited O2 minus production. O2 minus production did not take place under N2. Agents that affect cell motility were also examined. Colchicine and vinblastine, alkaloids which affect microtubule function, had little effect on granulycote O2 minus production. On the other hand, cytochalasin B, a fungal antimetabolite thought to affect microfilaments, inhibited O2 minus production by resting granulocytes and stimulated its production by cells incubated with bacteria. The mechanism and significance of this effect remain to be elucidated.

A study of cometary eruptions through OH radio-lines

1999 ◽  
Vol 173 ◽  
pp. 249-254
Author(s):  
A.M. Silva ◽  
R.D. Miró
Keyword(s):  
Short Duration ◽  
Growth Curves ◽  
The Other ◽  
Initial Mass ◽  
Radio Lines ◽  
Other Hand ◽  
Sudden Rise

AbstractWe have developed a model for theH2OandOHevolution in a comet outburst, assuming that together with the gas, a distribution of icy grains is ejected. With an initial mass of icy grains of 108kg released, theH2OandOHproductions are increased up to a factor two, and the growth curves change drastically in the first two days. The model is applied to eruptions detected in theOHradio monitorings and fits well with the slow variations in the flux. On the other hand, several events of short duration appear, consisting of a sudden rise ofOHflux, followed by a sudden decay on the second day. These apparent short bursts are frequently found as precursors of a more durable eruption. We suggest that both of them are part of a unique eruption, and that the sudden decay is due to collisions that de-excite theOHmaser, when it reaches the Cometopause region located at 1.35 × 105kmfrom the nucleus.

Closing the GAP—A 5Å Scanning Microscope

1969 ◽  
Vol 27 ◽  
pp. 6-7
Author(s):  
A. V. Crewe
Keyword(s):  
Normal Form ◽  
The Other ◽  
Resolving Power ◽  
Scanning Microscope ◽  
Conventional Microscope ◽  
Other Hand ◽  
Closing The Gap ◽  
Thermal Sources ◽  
Better Than ◽  
Transmission Microscope

We have become accustomed to differentiating between the scanning microscope and the conventional transmission microscope according to the resolving power which the two instruments offer. The conventional microscope is capable of a point resolution of a few angstroms and line resolutions of periodic objects of about 1Å. On the other hand, the scanning microscope, in its normal form, is not ordinarily capable of a point resolution better than 100Å. Upon examining reasons for the 100Å limitation, it becomes clear that this is based more on tradition than reason, and in particular, it is a condition imposed upon the microscope by adherence to thermal sources of electrons.

Life Beyond 1MeV

1980 ◽  
Vol 38 ◽  
pp. 30-33
Author(s):  
K.H. Westmacott
Keyword(s):  
Electron Microscopy ◽  
Past Experience ◽  
The Other ◽  
Good Case ◽  
Other Hand ◽  
The U.S

Life beyond 1MeV – like life after 40 – is not too different unless one takes advantage of past experience and is receptive to new opportunities. At first glance, the returns on performing electron microscopy at voltages greater than 1MeV diminish rather rapidly as the curves which describe the well-known advantages of HVEM often tend towards saturation. However, in a country with a significant HVEM capability, a good case can be made for investing in instruments with a range of maximum accelerating voltages. In this regard, the 1.5MeV KRATOS HVEM being installed in Berkeley will complement the other 650KeV, 1MeV, and 1.2MeV instruments currently operating in the U.S. One other consideration suggests that 1.5MeV is an optimum voltage machine – Its additional advantages may be purchased for not much more than a 1MeV instrument. On the other hand, the 3MeV HVEM's which seem to be operated at 2MeV maximum, are much more expensive.

Can the Academic Self-Concept be Positive and Realistic?

2005 ◽  
Vol 19 (3) ◽  
pp. 129-132 ◽  
Author(s):  
Reimer Kornmann
Keyword(s):  
Academic Performance ◽  
Opposite Effect ◽  
Self Esteem ◽  
Point Of View ◽  
The Other ◽  
Self Concept ◽  
High Ability ◽  
Self Image ◽  
Other Hand

Summary: My comment is basically restricted to the situation in which less-able students find themselves and refers only to literature in German. From this point of view I am basically able to confirm Marsh's results. It must, however, be said that with less-able pupils the opposite effect can be found: Levels of self-esteem in these pupils are raised, at least temporarily, by separate instruction, academic performance however drops; combined instruction, on the other hand, leads to improved academic performance, while levels of self-esteem drop. Apparently, the positive self-image of less-able pupils who receive separate instruction does not bring about the potential enhancement of academic performance one might expect from high-ability pupils receiving separate instruction. To resolve the dilemma, it is proposed that individual progress in learning be accentuated, and that comparisons with others be dispensed with. This fosters a self-image that can in equal measure be realistic and optimistic.

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