Gram Of Fresh Weight Research Articles

Effect of malnutrition on experimental allergic encephalomyelitis

Summary One-month-old Lewis rats on low protein-isocaloric diets (malnutrition) since birth failed to develop experimental allergic encephalomyelitis (EAE), while all control animals showed severe EAE 14–21 days after injection of guinea pig spinal cord or guinea pig basic protein emulsion in complete Freunds adjuvant. Two- or 3-month-old or adult malnourished animals were not protected from EAE. Weights of brains and spinal cords of malnourished animal were reduced by a factor of 15–30%, but myelin yielding per gram of fresh weight and myelin proteins were similar in control and malnourished animals. Qualitative differences in myelin proteins of malnourished and control animals were not detected on polyacrylamide gel electrophoresis. It remains to be determined whether changes of myelin encephalitogenic proteins, immune suppression or both factors are responsible for the profound temporary inhibitory effect of malnutrition on EAE.

5-Hydroxytryptamine and Dopamine in Biomphalaria glabrata

5-hydroxytryptamine (5-HT) and dopamine (DA) have been isolated and identified in the tissues of the snail, Biomphalaria glabrata. The brain contained approximately 15 tAg, the cephalopedal region 2 ,ug, and the mantle region 1 jug of 5-HT per gram of fresh weight. The concentrations of DA in the brain and the cephalopedal region were of the same order of magnitude as those of 5-HT, and 5 times lower in the mantle region. Neither 5-HT nor DA were detectable in the hepatopancreas-ovotestis region. The distribution of these 2 biogenic amines was also studied by the histochemical fluorescence technique of Falck and Owman (1965). Only green (catecholamine) fluorescent neurons were observed in the buccal ganglia; they are tentatively considered as DA neurons. Neuropile areas probably contain a mixture of 5-HT and DA. The nerve fibers emanating from the ganglia predominantly contain DA. With the exception of the buccal ganglia, 5-HT neurons were more numerous and comparatively large in the other ganglia. Green catecholamine fluorescence was detected in areas nearest to the epithelium of the foot. The presence of two biogenic amines, 5hydroxytryptamine (5-HT) and dopamine (DA), has been demonstrated in a variety of gastropods (Carpenter et al., 1971; Cottrell and Maser, 1967; Dahl et al., 1966; Gerschenfeld, 1971; Sweeney, 1963; Twarog, 1968; Walker et al., 1968; Kerkut and Cottrell, 1963; Kerkut et al., 1966). These amines are localized predominantly in the nervous system of this class of animals, and evidence for their function as neural transmitters has been reported (Carpenter et al., 1971; Dahl et al., 1966; Gerschenfeld, 1971; Gerschenfeld and Stefani, 1968; Sweeney, 1963; Twarog, 1968). The gastropod Biomphalaria glabrata is an intermediate host of the parasitic trematode, Schistosoma mansoni. 5-HT and norepinephrine have been identified as constituents of the adult form of this parasite (Bennett et al., 1969; Bennett and Bueding, 1971). Furthermore, recent evidence indicates the presence of dopamine receptors in the longitudinal muscle of adult S. mansoni, a function of 5-HT as an excitatory neuromuscular transmitter in the parasite. (T. Tomosky et al., 1974), and a high affinity uptake Received for publication 2 November 1973. * This investigation was supported by NIH training grant AI-149, and research grants AI-03515 and AI-08022. t Present address: National Institute of Child Health and Human Development, Gerontology Research Center, Baltimore City Hospitals, Baltimore, Maryland 21224. mechanism for 5-HT providing a neurotransmitter which the adult worm cannot synthesize de novo. The question arises whether biogenic amines play a role in the development of the larval stages of schistosomes in their intermediate host; this, in turn, requires information about the distribution of these amines in B. glabrata. The present study is concerned with this problem. MATERIALS AND METHODS Biomphalaria glabrata with shell diameters of 9 to 14 mm were used. Determination of biogenic amines The tissues were dissected, quickly frozen in liquid nitrogen, and homogenized in a solution containing perchloric acid (0.4 M), ascorbic acid (10 mM), and EDTA (5.4 mM) (Anden and Magnusson, 1967) in a motor-driven all-glass homogenizer at 4 C. One ml of solution was used per 100 mg tissue. The mixture was transferred into a centrifuge tube and, after washing of the container with a measured volume of the same solution, was centrifuged at 10,000 g for 15 min at 4 C. The pH of the supernatant solution was adjusted to 5 to 6 by addition of 0.5 ml of 2 M potassium phosphate buffer (pH 6.5) and a measured volume of 2 N KOH. After centrifugation (10,000 g, 15 min, 4 C) the supernatant solution was used for the determinations of 5-HT and of DA.

Studies on the Mechanism of Glycerate 3-Phosphate Synthesis in Tomato and Maize Leaves

The net carbon incorporation in maize (Zea mays) and tomato (Lycopersicum esculentum) leaves was mainly the result of the carboxylation of ribulose 1,5-diphosphate. In both of these organisms synthesis of glycerate 3-phosphate was studied during short chase experiments (2 or 3 seconds in (14)CO(2) then 8 to 27 seconds in unlabeled CO(2)). Changes in the radioactivity in the individual carbon atoms of glycerate 3-phosphate, malate, and aspartate are consistent with the formation, in both leaves, of 2 molecules of glycerate 3-phosphate for each CO(2) molecule incorporated. The CO(2), before reacting with ribulose 1,5-diphosphate, is first incorporated in an intracellular CO(2) pool which has a different composition according to the species. This pool is constituted in tomato by volatile compounds (50 nanomoles per gram of fresh weight) more or less in equilibrium with atmospheric CO(2). In maize the pool consists of carbon atoms 4 of malate and aspartate (for at least 80% of the pool) and volatile compounds which correspond, in all, to 540 nanomoles per gram of fresh weight where atmospheric CO(2) enters through an irreversible reaction.

Effect of DMSO and Surfactant Combinations on Tissue Concentrations of Picloram

Over a 2-year period no treatment differences were noted in 4-amino-3,5,6-trichloropicolinic acid (picloram) concentrations recovered from grass and yaupon(Ilex vomitoriaAit.) tissues treated with 1.12 kg/ha of picloram in mixture with dimethyl sulfoxide (DMSO) and surfactant (X-77).4Less than 1 μg of picloram per gram of fresh weight of grass or yaupon was present in aerial tissue 6 months after treatment, in yaupon stem tissues 1 month after treatment, and in yaupon root tissue 5 days after treatment. Tissues sampled 1 year after treatment were devoid of picloram residue; tissues sampled 1 year after retreatment had levels ranging from 0.04 to 0.26 μg/g. The April application of 1.12 kg/ha of picloram plus 5.0% X-77 plus 10.0 or 25.0% of DMSO produced more effective canopy reduction of yaupon 1 year after treatment than did other herbicide treatments or dates of treatment. Increased canopy reduction by retreatment the second year suggests that X-77 rather than DMSO was the effective component in the spray mixtures.

The Effect of Nitrogen Deficiency On the Growth of Meloidogyne Javanica At Different Population Levels

The rates of growth of M. javanica at different population levels have been measured in tomatoes grown on either full nutrient or in the absence of nitrogen. At low inoculation levels (40 larvae/plant) there is an acceleration of growth in nitrogen deficient plants. At higher inoculation levels (400 larvae/plant) this rate of growth declines and is significantly less than in plants grown on full nutrient. At higher inoculation levels (4000 larvae/plant) the rates of growth of the nematodes in both treatments is considerably reduced. Males were found in the treatments in which the ratios of number of nematodes in inoculum per gram of fresh weight of plant were highest. At the highest inoculation levels the nematodes significantly influenced the rates of growth of tomato plants grown either on full nutrient or in the absence of nitrogen, although this was more pronounced in the absence of nitrogen. The hypothesis is advanced that the rate of growth of M. javanica is related to the degree of stress to which it is subjected. A little stress leads to an acceleration in the rate of growth and further stress leads to the production of males and a slowing down of the overall rate of growth of the particular population under consideration.

Chemical Composition of Potatoes. I. Preliminary Studies on the Relationships Between Specific Gravity and the Nitrogenous Constituents

SUMMARYKatahdin potatoes (1959 crop) were placed in storage at 38°F. Monthly samples were removed and separated into three specific‐gravity levels‐‐‐high, intermediate, and low. Total solids changed but little in storage, indicating that shrinkage is due to a loss of both solids and water in the ratio in the original composition. Total and soluble nitrogen analyses over 10 months demonstrated an inverse relationship between total solids and these constituents when calculated on a moisture‐free basis. The nitrogen per gram of fresh weight shows no significant difference between samples of different solids contents. Therefore, the apparent inverse relationship on a moisture‐free basis is due to the storage of other constituents, presumed to be principally starch, in the case of high‐solids potatoes. About 60‐62% of the nitrogen is extracted by 70% by weight ethanol. Subsampling of large lots of potatoes for specific‐gravity studies is extremely difficult. All data should be checked for variations from sampling error.

EFFECT OF AGE OF LEAVES UPON THE RATE OF PHOTOSYNTHESIS IN SOME CONIFERS

Information regarding the relationship between photosynthesis and the complex of internal factors encompassed by the term, age, may be of interest either from the point of view of basic science or of practical application. The literature on this subject appears to be rather meager. Singh and Lal (2) working with different aged leaves of flax, sugar cane, and wheat found that the rates of photosynthesis were slow for young leaves, increased to a maximum for mature leaves, and then decreased with increasing age. From studies on aging effects in Chlorella cultures, Winokur (5) reported that the rate of photosynthesis, expressed either per unit number of cells or per unit dry weight, increased during the first few days of a culture and then declined with increasing age of the culture. It would appear that those conifers which maintain their leaves for several years would be especially appropriate for the study of the effects of aging on processes in the leaves. St?lfelt (3) investigated the rates of photosynthesis in spruce and pine with respect to age of needles and light intensity. He concluded for spruce that the rate of photosynthesis, when calculated per gram of fresh weight of needles, appeared to decrease with increasing age of the needles only because the weight of the needles increased with age; whereas actually the rate per unit number of leaves increased with increasing age for five years before declining. The results were most marked at about 30% of full sunlight but were quite evident both below and above this light intensity. For pine, in 30% of full sunlight, he found a similar increase in the amount of photosynthesis per unit number of leaves with increasing age up to three years, the oldest used; but in full sunlight the rate was approximately the same for leaves of all ages. From this review of literature, one may conclude that for some plants the peak photosynthetic capacity is reached at the time of maturity of the photosynthetic organ or structure, but in conifers the peak is not reached until the leaves are several years old. The purpose of the research reported in this paper was to obtain further data regarding the rates of photosynthesis in conifer leaves of varying age.

Riboflavin Content of Blood and Muscle in Normal and in Malnourished Humans.

Summary and Conclusions1. The blood riboflavin values of 20 normal subjects ranged between 0.35 and 0.45 μg per ml, with an average value of 0.42 μg per ml. The same range of riboflavin values was found in a group of 35 patients with varying degrees of riboflavin deficiency. The average value for this group was 0.40 μg of riboflavin per ml.2. The muscle riboflavin values of 9 control subjects ranged between 2.2 and 3.5 μg per gram of fresh weight with an average value of 2.9 μg per gram. The muscle riboflavin values for 30 pellagrins lay within the same range with an average value of 2.8 μg per gram of fresh muscle.3. From these results we have concluded that a determination of blood and muscle riboflavin values is of little significance in the evaluation of a state of riboflavin deficiency in man.

UREASE DISTRIBUTION IN CANAVALIA ENSIFORMIS

Urease activity is expressed in urease units. A urease unit (U.U.) is a quantity of urease which will produce 1 mg. of ammonia per minute when acting upon urea under the experimental conditions employed (2). The indicator method is not as sensitive as the quantitative method, and tissues containing less than 0.02 U.U. per gram of fresh weight are reported as negative with this method. Tissues containing less than 0.0001 U.U. are reported as negative with the quantitative method. The hypocotyl is that part of the axis between the cotyledonary node and the external collet.