Effect of cold environment on skeletal muscle mitochondria in growing rats

Summary Growing rats (4 weeks old) were kept for 3 weeks at 11° C and 24° C respectively. The cold-adapted animals showed a significantly higher oxygen consumption (64%). Volume density of subsarcolemmal and interfibrillar mitochondria as well as volume density of fat droplets were estimated in M. soleus and the diaphragm of both groups. In cold-adapted animals, the total volume of mitochondria was significantly increased by 24% in diaphragm and 37% in M. soleus. The volume of subsarcolemmal mitochondria was almost doubled in each muscle, but the volume of interfibrillar mitochondria did not change significantly. The surface of the inner mitochondrial membranes per unit volume of mitochondrion in M. soleus was significantly increased both in interfibrillar and subsarcolemmal mitochondria, whereas the surface of the outer mitochondrial membranes per unit volume of mitochondrion was increased only in the subsarcolemmal mitochondria. The volume of fat droplets in the diaphragm and M. soleus of cold adapted animals increased significantly by 62% and 150% respectively.     

Vascularization of the lateral muscle of some elasmobranchiomorph fishes

The vascular bed of the locomotor muscle in three shark species and in a holocephalan is investigated and the capillarization quantified by morphometrical methods. The red muscle fibres of Scyliorhinus, Galeus, Etmopterus and Chimaera are well vascularized having respectively 25, 18, 23 and 5 per cent of fibre surface covered by capillaries. The white muscle fibres of Scyliorhinus are far better vascularized than white muscle fibres of Galeus, Etmopterus and Chimaera . The fibre surface covered by capillaries are 9, 1.4, 0.2 and 1.3 per cent, respectively. The intermediate muscle fibres have a vascular supply between that of red and white muscle fibres in all species. If the capillary contact area to the fibres are related to the mitochondrial volume, more similar values are obtained for the vascular supply to all fibres types in all animals. This parameter indicates that there is a definite relation between the capacity of the oxygen transport system and the aerobic metabolic machinery.     

ULTRASTRUCTURE OF THE RESTING AND CONTRACTED STRIATED MUSCLE FIBER AT DIFFERENT DEGREES OF STRETCH

Passive stretch, isometric contraction, and shortening were studied in electron micrographs of striated, non-glycerinated frog muscle fibers. The artifacts due to the different steps of preparation were evaluated by comparing sarcomere length and fiber diameter before, during, and after fixation and after sectioning. Tension and length were recorded in the resting and contracted fiber before and during fixation. The I filaments could be traced to enter the A band between the A filaments on both sides of the I band, creating a zone of overlap which decreased linearly with stretch and increased with shortening. This is consistent with a sliding filament model. The decrease in the length of the A and I filaments during isometric contraction and the finding that fibers stretched to a sarcomere length of 3.7 µ still developed 30 per cent of the maximum tetanic tension could not be explained in terms of the sliding filament model. Shortening of the sarcomeres near the myotendinous junctions which still have overlap could account for only one-sixth of this tension, indicating that even those sarcomeres stretched to such a degree that there is a gap between A and I filaments are activated during isometric contraction (increase in stiffness). Shortening, too, was associated with changes in filament length. The diameter of A filaments remained unaltered with stretch and with isometric contraction. Shortening of 50 per cent was associated with a 13 per cent increase in A filament diameter. The area occupied by the fibrils and by the interfibrillar space increased with shortening, indicating a 20 per cent reduction in the volume of the fibrils when shortening amounted to 40 per cent.     

The Effect of Nitrogen on the Growth and Sugar Content of Sugar-beet

Nitrogen fertilizer applied to sugar-beet increased plant androot dry weight and leaf area, and decreased the sugar contentof the roots per cent of both fresh and dry weight. Change inleaf area accounted wholly for the increase in plant dry weightproduced by nitrogen, because net assimilation rate was unaffected.Nitrogen did not alter the partition of the total assimilatebetween roots and shoots, but increased the fraction of totalassimilate entering the roots that was used in growth, at theexpense of that stored as sugar. Thus, plants with more nitrogenhad a smaller proportion of their root dry weight as sugar becausemore was metabolized in growth of the roots, and not becauseless entered the roots. The heavier roots of plants given more nitrogen were largerin cross-sectional area because the areas of both parenchymaand vascular zones of each peripheral ring within the root werelarger; the number of rings was not increased. Nitrogen increasedthe areas of the tissues in these zones by enlarging cell volumes,not by increasing the number of cells within the tissues. Increasein cell volume was accompanied by proportional increases inthe weights of non-sugar dry matter per cell and water per cell,but the amount of sugar per cell was proportional to cell volumeonly during the initial stage of cell expansion up to cell volumesof about 15x10^–8 cm²; thereafter it was less than proportional,so that sugar per cent of both fresh and dry weight decreasedas cell size increased beyond 15x10^–8 cm². The relationof sugar per cell to cell volume was the same with both amountsof nitrogen given. This implies that increase in nitrogen supplymade the sugar concentration of the root less by increasingthe size of the root cells and not by a specific effect on sugarstorage.     

Nuclear and Cell Sizes in Different Regions of Root Meristems of Zea mays L.

Nuclear volumes and cell areas were determined for seven regionsof the meristem of roots of Zea mays. Roots were fixed in 10per cent neutral buffered formalin, in 3 per cent glutaraldehydeor in acetic acid/alcohol; they were prepared as sections oralls were teased apart. Mean volumes of interphase nuclei weresimilar in all regions of the root except the vascular tissueof the stele. Mean nuclear volumes and the overall range ofvolumes were similar in sub-populations of cells with differentproportions of G¹, S and G² cells, e.g. in row I of root capinitials, whose cells lack a G¹ phase, and in quiescent centrecells, which are mainly in G¹. Nuclear volume does not appearto be closely correlated with DNA content. Nuclear volumes covereda 6 to 12-fold range within a meristem and even within specificregions, in which cells are part of the same cell lineages,there was a 4- to 9-fold range. Nuclear volumes were comparedin sister cells in rows I and II of the root cap initials. In10 per cent of the pairs, sister nuclei had identical volumes;the other pain had different volumes and mean difference was68 µm³. Mechanisms by which this variability could begenerated are discussed, particularly asymmetry, at mitoses,of factors that regulate nuclear growth. Zea mays L., nuclear volume, cell size, root mcristem, DNA content, mitosis     

On the cell wall composition of the apiculate yeasts

Summary Sonic oscillation was used for the purpose of obtaining clean, chemically intact cell walls. The rate of disruption was determined for cells ofHanseniaspora uvarum andSaccharomyces cerevisiae. The carbohydrate fractions of cell walls ofHanseniaspora uvarum, H. valbyensis, Kloeckera apiculata, Saccharomycodes ludwigii andSaccharmyces cerevisiae were shown to be similar. Chromatography of cell wall hydrolysates of all these species demonstrated that glucose and mannose were the only sugars present (in about equal amounts) besides traces of glucosamine. The cell walls ofH. uvarum contained 78.1 per cent carbohydrates, 7 per cent protein and approximately 0.05 per cent of chitin. Fractionation of the polysaccharides lead to a recovery of 83.3 per cent of the carbohydrates present (30.4 per cent glucan and 34.9 per cent mannan). Saccharomyces cerevisiae cell walls were found to have a carbohydrate content of 82.8 per cent, 6.5 per cent protein and a trace of chitin (0.04 per cent). Nadsonia elongata contained a relatively large amount of chitin (ca. 5 per cent) and lacked mannan in its cell walls. It was concluded thatHanseniaspora andSaccharomycodes are closely related to theSaccharomyceteae but they have little in common with species ofNadsonia.     

The supply of nutrient ions by diffusion to plant roots in soil

Summary Observation of soil grown roots of rye-grass shows that an approximately cylindrical volume of soil, the root hair cylinder, is densely occupied by root hairs. Estimates are given of the concentration of labile and solution potassium within the root hair cylinder during experiments measuring potassium uptake from two soils by single roots. Calculations, using a diffusion model, suggest that labile potassium concentrations may be reduced to between 99.3 and 53 per cent of the initial, depending on the diffusion characteristics of the soil and nutrient demand by the root. Of the total potassium absorbed by a root in 4 days, the proportion which is supplied from within the root hair cylinder is small (0.8 to 6.3 per cent) indicating that diffusion to the root from the soil outside the root hair cylinder is of paramount importance. When root demand is high, diffusion appears to limit uptake to between 71 and 59 per cent of that which roots of comparable physiology would be expected to absorb from stirred solution of the same concentration. Nevertheless, the presence of root hairs is calculated to have enhanced uptake by up to 77 per cent compared with roots without hairs because they virtually increase the root diameter. Diffusion does not appear to be a limiting factor when root demand is low and hairs can then add little to the efficiency of the root system in potassium absorption.     

Cellular Differentiation and Tissue Partitioning in Caps of Primary and Lateral Roots of Helianthus annuus

Cellular and tissue volumes in caps of primary and lateral rootsof Helianthus annuus have been measured in order to determinequantitatively how tissues and their functions are partitionedin root caps. Patterns of change in cellular dimensions andvolumes are similar in caps of primary and lateral roots. Significantincreases in cellular dimensions and volume occur during thedifferentiation of columella cells and the innermost peripheralcells. There are no significant changes in cellular dimensionsas either (i) the production and secretion of mucilage begins,or (ii) cells are sloughed from the cap. Tissues are partitionedsimilarly in caps of primary and lateral roots. indeed, rootcaps allocate 7–8 per cent of their volume for regeneration(i.e. calyptrogen tissue), 16–19 per cent of their volumefor graviperception (i.e. columella tissue), and approx. 38per cent of their volume for the production and secretion ofmucilage. These results are discussed relative to patterns ofcellular differentiation and tissue function in root caps. Helianthus annuus, root caps, primary root, lateral root, calyptrogen, columella, peripheral cells, tissue partitioning     

A Morphometric Analysis of the Ultrastructure of Columella Statocytes in Primary Roots of Zea mays L.

A morphometric analysis of the ultrastructure of columella statocytesin primary roots of Zea mays was performed to determine theprecise location of cellular organelles in graviperceptive cells.Vacuoles occupy the largest volume in the cell (11.4 per centof the protoplasm). The nucleus (9.51 per cent), amyloplasts(7.57 per cent), mitochondria (3.42 per cent), spherosomes (2.13per cent) and dictyosomes (0.55 per cent) occupy progressivelysmaller volumes of the statocytes. All organelles are distributedasymmetrically within the cell. Amyloplasts, spherosomes anddictyosomes are found in greatest numbers (and relative volumes)in the lower (i.e. ‘bottom’) third of the cell.The largest numbers and relative volumes of mitochondria arein the lower and middle thirds of the cell. Nuclei tend to befound in the middle third of the statocytes. Only the hyaloplasmis concentrated in the upper (i.e. ‘top’) thirdof Z. mays statocytes. When the sedimentation of amyloplasts(and the resulting exclusion of other organelles from the lowerthird of the cell) is corrected for, all cellular constituentsremain asymmetrically distributed within the cell. Therefore,the sedimentation of amyloplasts alone is not responsible forthe differential distribution of other cellular organelles inZ. mays statocytes. The quantitative ultrastructure of Z. maysstatocytes is discussed relative to the graviperceptive functionof these cells. Zea mays, corn, maize, root cap, stereology, columella, statocytes, graviperception, ultrastructure     

The growth and development of the storage root of sugar beet

A study was made of the growth of the storage root of sugar beet as a sugar accumulating organ. The storage root grew by simultaneous cell multiplication and expansion from a series of peripheral secondary meristems laid down during the early stages of development. The weight of water and of non-sugar dry matter per cell increased in proportion to the increase in cell volume. The amount of sugar per cell was proportional to cell volume only during the initial stage of cell expansion up to volumes of about 15 times 10^-8 cm³; thereafter it was less proportional. Thus, average cell size is a major determinant of the sugar concentration of the storage root. The implications of this are discussed.     

Radioiodination of L 1210 cells.

The lymphoid leukaemia L 1210 cells of mice were labelled with 125I. The cell homogenates were fractionated and from the microsomal fraction 90 per cent of the radioactive material could be precipitated with perchloric acid, whereas only 4 per cent was precipitated from the soluble fraction. Papain bound with Enzacryl AH released 31 per cent of radioactivity. It was concluded therefrom that the surface proteins of the cells were labelled. Electrophoretic separation of these proteins in polyacrylamide gel with sodium dodecyl sulphate was performed and 6--8 radioactive fractions of surface peptides were found.     

Quantitative interrelationship between the parenchyma and the stroma of the rabbit myocardium in atherosclerotic cardiosclerosis]

The relative volume of myocardial fibers, connective tissue cells, capillaries, interstitial space and surface area of the myocardial fibers and capillaries per tissue volume unit of the myocardium were measured during diffuse cardiosclerosis under conditions of experimental atherosclerosis. A significant decrease in the relative volume of the myocardial fibers alone with a concomitant increase of the extracellular space of the stroma were demonstrated.     

CONSIDERATIONS OF POSTOPERATIVE ELECTROLYTE AND FLUID REPLACEMENT

The most important postoperative fluid considerations are maintenance of adequate urinary output, of blood volume, and of extracellular and interstitial cell water and electrolytes.Normal urinary output is between 1,000 and 1,500 cc. daily. A fluid intake of 2,000 cc. of 5 per cent dextrose in distilled water, plus 500 cc. of normal saline solution, will insure this amount of urinary output.The use of 5 per cent dextrose solutions in distilled water provides fluid, retards the protein catabolism of the body, and spares electrolytes.Irradiated plasma is the only intravenous solution which will adequately supply protein in amounts to maintain nitrogen equilibrium. Protein hydrolysates in the absence of adequate caloric intake do not provide enough protein for nitrogen balance.The role of the potassium ion is ordinarily not a consideration in postoperative fluid management. It becomes a consideration in the presence of a large amount of drainage from wounds or abscess cavities, nasogastric suction, or intestinal fistulae. It also must be given attention in cases in which parenteral administration of fluids is necessary for a prolonged period.     

Method of membrane filtration for determining the sterility and microbial contamination of antibiotics]

During membrane filtration antibiotics belonging to different chemical groups are strictly absorbed on the filters. When the filters are put into liquid thioglycol medium, the residual amounts of the antibiotics on the filters did not prevent the growth of sensitive microflora experimentally added to the drug. When the filter was put onto solid nutrient medium, only resistant forms of the microbes grew as a rule on its surface, the amount of the grown microbes being 26--43 per cent of the added one. The sensitive microbes grew only in the amount of 0.3--1.3 per cent. Subsequently the residues of the antibiotic adsorbed on the filter inhibited the growth of the sensitive and partially resistant microflora.     

Absorption of Foliar-Applied 32P by Successive Leaves, and Distribution Patterns in Relation to Early Fruiting and Abscission in the Cowpea (Vigna unguiculata L.)

In controlled environment experiments, the uptake and distributionpatterns of ³²P were studied in relation to flowering and fruitingin the cowpea. Absorption by the plant, retention by the fedleaf, and translocation to various plant parts depended on theposition and age of the fed leaf. At the 4-leaf stage, whenthe terminal leaflet of the first trifoliate (oldest) was fed³²P, the plant absorbed 43 per cent of total radioactivity suppliedin 24 h. The percentages resulting from the feeding of trifoliates2, 3, and 4 (youngest) were 58, 71, and 73 respectively. Trifoliate1 retained 34 per cent of the total radioactivity, while trifoliate4 retained 68 per cent. Of the plant tissues, the root accumulatedthe greatest amounts of the P exported by the fed leaflet, withthe feeding of trifoliates 1, 2, or 3. With the feeding of trifoliate4, however, the root imported only 0.2 per cent of total radioactivity. When the plants had one set of flowers fully open at raceme1, the flowers imported 0.19 per cent of total radioactivityin the cultivar Adzuki, and 0.36 per cent in the cultivar EarlyRamshorn. When the raceme 1 flowers developed into fruits whilethe raceme 2 flowers were fully open, the raceme 1 fruit importof radioactivity was 2.61 per cent in Adzuki and 14.21 per centin Early Ramshorn. Raceme 1 fruits of Early Ramshorn thus accumulatedfive times as much P radioactivity as those of Adzuki. Whenracemes 1 and 2 both bore fruits, removal of the raceme 1 fruitsjust prior to ³²P feeding, led to the import by the raceme 2fruits of 0.25 per cent in Adzuki and 0.09 per cent in EarlyRamshorn. The raceme 1 fruits constituted a more potent sinkfor ³²P in Early Ramshorn than in Adzuki. The results are discussedin relation to the known patterns of premature abscission offlowers and young fruits in the two cultivars.     

Transient correction of genetic defects in cultured animal cells by introduction of functional proteins.

Material was introduced into cultures of cells by using the method of scrape loading, in which cells are simply rubbed from the surface of a plastic tissue culture dish by a rubber-tipped rod in the presence of a macromolecule of interest. The volume of solution introduced into cells was comparable to that generally injected in the direct microinjection method with glass capillaries, that is, about 50 to 100 fl per cell. Genetic defects (lack of hypoxanthine-guanine phosphoribosyltransferase and thymidine kinase) in several cell lines were transiently corrected by scraping the cells in the presence of crude cell extracts prepared from wild-type cells.     

Structure of the interstitial space and ground substance of the human articular cartilage

By means of transmissive and scanning electron microscopy (investigation of ultra-replicas) three-dimensional organization of the interstitial (interfibrillar) space of the articular cartilage has been demonstrated; it repeats, to some extent, construction of the fibrous base. By means of mercury porometry quantitative characteristics of various parameters of the interfibrillar space are obtained. Their specific volume is 0.96 cm3/g of the dehydrated cartilage, space with equivalent diameters from 300 up to 5 nm makes 94%. By means of the gas adsorption method it has been stated that the specific internal surface is 23.8 m2 per 1 g of the dehydrated articular cartilage. Transmissive and scanning electron histochemistry has revealed several various forms of structured proteoglycans, demonstrated their spatial organization and interconnection with collagenous fibrils. The methodical complex applied can be used for investigating the connective tissue interstitial spaces in other parts of the human locomotor apparatus.     

Loss of Viability in Lettuce Seeds and the Accumulation of Chromosome Damage under Different Storage Conditions

Loss of seed viability in lettuce (Lactuca sativa L.) duringstorage is associated with an increase in the frequency of cellsin the surviving seeds showing chromosome damage during firstmitoses. The relation is linear when probit of the frequencyof aberrant cells is plotted as a function of probit percentagenormal germination. The slope of the relation, however, variesaccording to moisture content so that the proportion of aberrantcells for any given loss of germination increases with decreasein moisture content over the range 13.0–5.5 per cent.At 3.3 per cent moisture content, however, the proportion ofaberrations was no greater than at 5.5 per cent moisture content;and at 18.1 per cent moisture content the proportion was noless than at 13.0 per cent moisture content. Despite these differences,the increase in chromosomal aberrations per unit time for agiven temperature was always less the lower the moisture content.Diplontic selection markedly reduced the frequency of chromosomalaberrations and eliminated the differences in these frequenciesbetween the different storage treatments. But even after fiveweeks' growth, root tips from aged seed still contained abouttwice as many aberrant cells as compared with similar root tipsderived from the original seed stock. Studies on the frequencyof recessive mutations indicated that excessive amounts of heritablemutations were not present in the progenies of aged seed, evenwhen stored at moisture contents as low as 5.5 per cent. Allthis and other evidence reinforces the view that orthodox seedsfor genetic conservation should be stored at not more than about5 per cent moisture content, and that even lower moisture contentsare worth considering. The results also emphasise the need formaintaining a high regeneration standard, i.e. the percentageto which seed viability is allowed to fall during storage beforethe seed stock is regenerated. Lactuca sativa, lettuce, seed storage, seed viability, chromosomal aberrations, phenotypic mutations     

Calcium equilibrium in muscle

1. A study of the calcium equilibrium in isolated frog muscle has been attempted. 2. When sartorius muscles were immersed in Ca(45) Ringer's solution, the surface phase took up the Ca(45) in about 1 minute; the extracellular water space and connective tissue in about 30 minutes; and the intracellular space in about 300 minutes. 3. The percentages of total calcium in the whole muscle immersed in Ringer's solution was as follows: 10 per cent in the surface phase; 12 per cent in the extracellular water space; 17 per cent in the dry connective tissue; 24 per cent in the intracellular space; and 37 per cent as non-exchangeable calcium. 4. The exchange constants of isolated frog sartorius muscle to calcium has been determined. The flux of intracellular calcium in the steady state was approximately 0.8 mM/(liter hr). 5. It appears that there is a calcium pump pushing calcium out of the cell against an electrochemical gradient of about 4 cal./mM of calcium. However, since the flux is low, the maximum energy required per hour to pump calcium out of the cell against this high gradient is only about 2 cal./kg. muscle or about 1 per cent of the resting energy.