The Concentrations of Dry Matter in Mitotic Apparatuses in Vivo and After Isolation From Sea-Urchin Zygotes

1972 ◽  
Vol 10 (2) ◽  
pp. 387-418
Author(s):  
A. FORER ◽  
R. D. GOLDMAN
Keyword(s):  
Sea Urchin ◽  
Dry Matter ◽  
Mass Medium ◽  
Dry Mass ◽  
Interference Microscopy ◽  
High Mass ◽  
Isolation Medium ◽  
High Ph ◽  
Cytoplasmic Material

We have measured the concentrations of dry matter in mitotic apparatuses (MA) in vivo and after isolation from the same cell type. The isolation medium was hexylene glycol plus buffer. The MA were from sea-urchin zygotes (Echinus esculentus Linn. and Psammechinus miliaris Gmelin), and measurements were made using interference microscopy. MA as isolated have much lower concentrations of dry matter than do MA in vivo. The dry mass concentrations of isolated MA vary with the pH of the isolation medium, ranging from about 20 % of the in vivo concentration (at pH 7.3) to about 60 % of the in vivo concentration (at pH 5.3). The isolated MA were further characterized. Evidence is presented which suggests that non-specific cytoplasmic material adsorbs to MA, and thus that at least some of the material in isolated MA is not derived from in vivo MA. Some MA components are apparently changed during the isolation procedure: MA lysed in low pH (high mass) medium and quickly transferred to high pH (low mass) medium have higher concentrations of dry matter than do MA lysed in high pH medium. The isolation media as generally used do not have enough buffering capacity: the pH changes after the isolation. These data suggest that the isolation procedures need be improved before studies of isolated MA can give data relevant to the chemistry of in vivo MA. We discuss the problem of obtaining functional isolated MA, and also the relevance of our data to previous work on MA from other species.

Spindle birefringence of isolated mitotic apparatus analysed by treatments with cold, pressure, and diluted isolation medium

1976 ◽  
Vol 20 (2) ◽  
pp. 329-339
Author(s):  
A. Forer ◽  
A.M. Zimmerman
Keyword(s):  
Electron Microscopy ◽  
Sea Urchin ◽  
Half Life ◽  
Cold Treatment ◽  
Pressure Treatment ◽  
Mitotic Apparatus ◽  
Isolation Medium ◽  
Spindle Structure ◽  
Cold Pressure

Mitotic apparatus (MA) were isolated from sea-urchin zygotes using glycerol-dimethyl-sulphoxide. Cold treatment had no effect on MA birefringence when MA were in isolation medium, but caused a 10–15% reduction of MA birefringence when MA were in quarter-strength isolation medium. Pressure treatment also caused a reduction in MA birefringence, but the cold and pressure treatments were not additive, suggesting that both treatments affected the same MA component. MA were not stable in quarter-strength isolation medium, and birefringence gradually decayed, with a half-life of about 40 h. Electron microscopy after cold treatment, or after decay of 55% of the MA birefringence showed abundant, normal-looking microtubules, suggesting that alterations in non-microtubule components cause the reductions in birefringence. Addition of EGTA eliminates the effect of cold treatment, suggesting that Ca2+ has a role in maintenance of spindle structure. We discuss possible reasons why isolated MA do not respond to cold treatment like MA in vivo.

Spindle birefringence of isolated mitotic apparatus analysed by pressure treatment

1976 ◽  
Vol 20 (2) ◽  
pp. 309-327
Author(s):  
A. Forer ◽  
A.M. Zimmerman
Keyword(s):  
Electron Microscopy ◽  
Sea Urchin ◽  
Dimethyl Sulphoxide ◽  
Pressure Treatment ◽  
Mitotic Apparatus ◽  
Isolation Medium ◽  
Hexylene Glycol ◽  
X 24 ◽  
Induced Changes

Sea-urchin zygote mitotic apparatus (MA) isolated in a glycerol/dimethylsulphoxide medium were treated with pressure. Pressure treatment had no effect on spindle birefringence when MA were in full-strength isolation medium. After placing MA in quarter-strength isolation medium, pressures of 4-0 X 10(3)-1-8 X 10(4) lbf in.-2 (2 X 76 X 10(4)-I X 24 X 10(5) k N m-2) for 15 min caused reduction of birefringence which occurred in 2 steps: firstly 20–30% of the birefringence was lost, and then, at higher pressures, the rest of the birefringence was lost. Electron microscopy suggested that pressure-induced changes were in non-microtubule material. Pressure treatment had no effect on MA isolated with hexylene glycol when the MA were pressurized in hexylene glycol; but pressure treatment did cause loss of birefringence when MA isolated in hexylene glycol were transferred immediately into glycerol/dimethylsulphoxide medium and were subsequently treated with pressure (after dilution into quarter-strength glycerol/dimethyl-sulphoxide). We discuss the differences in response between isolated MA and in vivo MA, and we discuss the possibility that 2 components contribute to MA birefringence.

The Action of Juvenile Hormone on the Follicle Cells of Rhodnius Prolixus: the Importance of Volume Changes

1977 ◽  
Vol 69 (1) ◽  
pp. 33-44 ◽  
Author(s):  
RANDA ABU-HAKIMA ◽  
K. G. DAVEY
Keyword(s):  
National Research Council ◽  
Dry Mass ◽  
Rhodnius Prolixus ◽  
Interference Microscopy ◽  
Follicle Cells ◽  
Volume Changes ◽  
Cross Sectional ◽  
Original Volume ◽  
Before And After

1. The onset of vitellogenesis in Rhodnius prolixus is marked by a reduction in the height of the follicle cells. This decrease is not observed in follicle cells from allatectomized females. Estimates of the changes in cross-sectional area of the cells suggest that the cells shrink to about 50% of their original volume as the result of JH action. 2. Determination by interference microscopy of the volume of isolated living follicle cells before and after exposure to JH also suggest that the volume is reduced to 50 % of the original volume as a result of JH action. There was no decrease in volume of follicle cells from allatectomized females following exposure to JH. 3. During mid to late vitellogenesis in vivo, an increase in cell volume was measured, an increase that possibly reflects an increase in cellular dry mass. 4. It is concluded that follicle cells normally respond to JH by pumping out fluid, thus reducing their volume, and leading to the development of spaces between the cells. Note: This work is supported by the National Research Council of Canada

Experimental determinations of tubulin in the in vivo mitotic apparatus of sea urchin zygotes

1980 ◽  
Vol 58 (11) ◽  
pp. 1277-1285 ◽  
Author(s):  
Arthur Forer ◽  
D. E. Larson ◽  
A. M. Zimmerman
Keyword(s):  
Sea Urchin ◽  
Gel Electrophoresis ◽  
Dry Matter ◽  
Strongylocentrotus Purpuratus ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Mitotic Apparatus ◽  
Cell Lysate ◽  
Hexylene Glycol

Mitotic apparatus (MA) were isolated from zygotes of a sea urchin (Strongylocentrotus purpuratus), using hexylene glycol (pH 6.4) as lysing–stabilizing agent. Protein was measured in the MA pellet and in the remainder of the cell lysate (using the Lowry procedure). Tubulin was measured in the MA pellet and in the remainder of the cell lysate (using microdensitometry of stained gels after sodium dodecyl sulphate – polyacrylamide gel electrophoresis). From these data we calculated the maximum possible amounts of tubulin in the isolated MA and in the MA in vivo; in these calculations we assumed that all the tubulin in the cell is associated with the MA, and we assumed that, as reported in the literature, the MA lose 90% of their dry matter during the isolation. We conclude that tubulin probably comprises less than 7% of the protein in the in vivo MA, and, even if there are very large errors, tubulin is considerably less than haf the protein in the MA.

Characteristics of Sea-Urchin Mitotic Apparatus Isolated Using a Dimethyl Sulphoxide/Glycerol Medium

1974 ◽  
Vol 16 (3) ◽  
pp. 481-497
Author(s):  
A. FORER ◽  
A. M. ZIMMERMAN
Keyword(s):  
Sea Urchin ◽  
Phosphate Buffer ◽  
Dry Matter ◽  
Room Temperature ◽  
Dimethyl Sulphoxide ◽  
Mitotic Apparatus ◽  
Isolation Medium ◽  
Hexylene Glycol ◽  
Brain Microtubules ◽  
Glycerol Medium

A method for isolating sea-urchin zygote mitotic apparatus (MA) is described which is based on the Filner-Behnke method of isolating brain microtubules. MA were isolated in 50% (v/v) glycerol, 10%(v/v) dimethyl sulphoxide, 5 mM MgCl2, 0.1 mM EGTA, and 5 mM Sørensen's phosphate buffer at a final pH of 6.8. MA stored at room temperature in isolation medium had stable birefringence, stable microtubules and stable solubility properties (in 0.5 M KCl) over a period of 10 days to 2 weeks. These MA also seem to have more dry matter per volume than do MA isolated using hexylene glycol. The biggest disadvantages of the method are that zygotes often are difficult to lyse, and that cytoplasmic debris the same size as the MA sometimes contaminates the MA pellet.

Optimum harvest date of maize for biogas and silage purposes

2009 ◽  
Vol 57 (2) ◽  
pp. 119-125
Author(s):  
G. Hadi
Keyword(s):  
Dry Matter ◽  
Biogas Production ◽  
Weather Conditions ◽  
Vegetation Period ◽  
Dry Mass ◽  
Matter Content ◽  
Harvest Date ◽  
Dry Matter Content ◽  
Dry Matter Yield ◽  
Vegetative Organs

The dry matter and moisture contents of the aboveground vegetative organs and kernels of four maize hybrids were studied in Martonvásár at five harvest dates, with four replications per hybrid. The dry matter yield per hectare of the kernels and other plant organs were investigated in order to obtain data on the optimum date of harvest for the purposes of biogas and silage production.It was found that the dry mass of the aboveground vegetative organs, both individually and in total, did not increase after silking. During the last third of the ripening period, however, a significant reduction in the dry matter content was sometimes observed as a function of the length of the vegetation period. The data suggest that, with the exception of extreme weather conditions or an extremely long vegetation period, the maximum dry matter yield could be expected to range from 22–42%, depending on the vegetation period of the variety. The harvest date should be chosen to give a kernel moisture content of above 35% for biogas production and below 35% for silage production. In this phenophase most varieties mature when the stalks are still green, so it is unlikely that transport costs can be reduced by waiting for the vegetative mass to dry.

In vivo apparent digestibility in ponies given rolled, micronised or extruded barley

1999 ◽  
Vol 1999 ◽  
pp. 133-133 ◽  
Author(s):  
B M L McLean ◽  
J J Hyslop ◽  
A C Longland ◽  
D Cuddeford ◽  
T Hollands
Keyword(s):  
Dry Matter ◽  
Latin Square ◽  
Design Experiment ◽  
Apparent Digestibility ◽  
Processing Methods ◽  
Physical Processing ◽  
Adaptation Phase

Processed cereals are used routinely in diets for equines but little information is available on how physical processing affects the digestibility of cereals in equines. This study examines the effects of three physical processing methods (rolling, micronisation and extrusion) on the in vivo apparent digestibility of barley fed to ponies.Three mature caecally-fistulated Welsh-cross pony geldings, (LW 284kg ± 3.8kg) were used in a 3 x 4 incomplete latin square changeover design experiment consisting of four 21 day periods. Each period comprised a sixteen day adaptation phase and a five day recording phase when apparent digestibility in vivo was determined. Ponies were offered 4kg dry matter (DM) per day of either 100% hay cubes (HC) or one of three diets consisting of a 50:50 barley:hay cubes mix. The barley in the mixed diets was either rolled barley (RB), micronised barley (MB) or extruded barley (EB). Diets were offered in 2 equal meals per day fed at 09:00 and 17:00 hours respectively.

The impact of elevated atmospheric CO2 and nitrate supply on growth, biomass allocation, nitrogen partitioning and N2 fixation of Acacia melanoxylon

1999 ◽  
Vol 26 (8) ◽  
pp. 737 ◽  
Author(s):  
Marcus Schortemeyer ◽  
Owen K. Atkin ◽  
Nola McFarlane ◽  
John R. Evans
Keyword(s):  
Elevated Co2 ◽  
N2 Fixation ◽  
Dry Matter ◽  
Co2 Concentration ◽  
Dry Mass ◽  
Nitrogen Partitioning ◽  
Atmospheric Co2 ◽  
Acacia Melanoxylon ◽  
Nitrate Supply ◽  
The Impact

The interactive effects of nitrate supply and atmospheric CO2 concentration on growth, N2 fixation, dry matter and nitrogen partitioning in the leguminous tree Acacia melanoxylon R.Br. were studied. Seedlings were grown hydroponically in controlled-environment cabinets for 5 weeks at seven 15N-labelled nitrate levels, ranging from 3 to 6400 mmol m–3. Plants were exposed to ambient (~350 µmol mol–1) or elevated (~700 µmol mol–1) atmospheric CO2 for 6 weeks. Total plant dry mass increased strongly with nitrate supply. The proportion of nitrogen derived from air decreased with increasing nitrate supply. Plants grown under either ambient or elevated CO2 fixed the same amount of nitrogen per unit nodule dry mass (16.6 mmol N per g nodule dry mass) regardless of the nitrogen treatment. CO2 concentration had no effect on the relative contribution of N2 fixation to the nitrogen yield of plants. Plants grown with ≥50 mmol m–3 N and elevated CO2 had approximately twice the dry mass of those grown with ambient CO2 after 42 days. The rates of net CO2 assimilation under growth conditions were higher per unit leaf area for plants grown under elevated CO2. Elevated CO2 also decreased specific foliage area, due to an increase in foliage thickness and density. Dry matter partitioning between plant organs was affected by ontogeny and nitrogen status of the plants, but not by CO2 concentration. In contrast, plants grown under elevated CO2 partitioned more of their nitrogen to roots. This could be attributed to reduced nitrogen concentrations in foliage grown under elevated CO2.

scholarly journals Do minke whales (Balaenoptera acutorostrata) digest wax esters?

1995 ◽  
Vol 74 (5) ◽  
pp. 717-722 ◽  
Author(s):  
Erling S. Nordøy
Keyword(s):  
Energy Density ◽  
Dry Matter ◽  
General Pattern ◽  
Dry Mass ◽  
Wax Esters ◽  
Gut Contents ◽  
Wax Ester ◽  
Balaenoptera Acutorostrata ◽  
Minke Whales

Mammals are known to utilize wax esters with an efficiency of less than 50%. The purpose of the present study was to examine whether or not minke whales (Balaenoptera acutorostrata), which at times may eat considerable amounts of wax-ester-rich krill, represent an exception to this general pattern. Samples of fresh undigested forestomach, as well as colon, contents were obtained from minke whales (n5) that had been feeding on krill (Thysanoessa inermis) for some time. The samples were analysed for dry mass, energy density, lipid content and the major lipid classes, including wax esters. The concentrations of wax esters were compared with previous estimates of dry-matter disappearance of the same type of prey using anin vitrotechnique, to calculate the dry-matter digestibility of wax esters (DMDwax). Wax esters contributed 21% of the energy and 47% of total lipids in the krill diet. The energy density of gut contents decreased by 50% after their passage from forestomach to the end of the colon. The DMDwaxwas 94·1 (SD 2·8)% (n5). This high DMDwaxand the occurrence of fatty alcohols, one of the products of wax-ester hydrolysis, in faeces show that minke whales are very efficient digesters of wax esters and absorb most of the energy-rich products of this process.

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