Content Of Nitrogenous Substances Research Articles

The influence of shelf life on the chemical composition of hulless barley

The feed value of grain undergoes changes during storage. During the post-harvest ripening of grain: polysaccharides, proteins, fats finish forming, the proportion of soluble carbohydrates, non-protein nitrogen decreases, the quality of gluten improves, the lipid content increases. The activity of enzymes decreases to the level characteristic of well-ripened grain. The purpose of the research was to study the influence of shelf life on the chemical composition of grain of hulless barley varieties. Studies have also been devoted to identifying changes in the feed value of varieties of hulless barley during storage. It has been found as a result of the research that Nudum 95 variety of hulless barley surpassed the pigmented analogue of Granal 32 variety in terms of the content of crude protein in the dry matter by 1,19 abs.% and was inferior in the content of crude ash by 0,09 abs.%, crude fat by 0,33 and nitrogen-free extractive substances by 0,78 abs.%. When storing grain of hulless barley, the content of nitrogenous substances in it increased slightly. For example, the content of crude protein in the dry matter of barley grains of the variety Nudum 95 increased by 0,71 abs.% during the first 6 months of storage, in the variety Granal 32 it increased by 0,44 abs.%. It has been found that the content of nitrogen-free extractive substances in barley grain decreased during the first months due to the consumption of carbohydrates for respiration. Thus, in the variety Granal 32 in the first month of storage, the amount of nitrogen-free extractive substances decreased by 0,59 abs.%, in the variety Nudum 95 for 3 months by 1,11 abs.%. The amount of raw fat during post-harvest ripening increased in the grain of variety Granal 32 by 0,26 abs.%, the variety Nudum 95 by 0,24 abs.%, then the decrease was observed.

Feed Parameters Influencing the Breeding of Mealworms (Tenebrio molitor)

With the growing public interest in edible insects, breeders are forced to increase the volume of production and shorten the life cycle of farmed insects. The exact composition of the feed is the know-how of each manufacturer. The aim of this work was to determine the general impact of individual conventional types of feed (bran, whey, raw ware potatoes) on the life cycle rate of Tenebrio molitor (TM), larval mortality and the content of fats, fatty acids and nitrogenous substances in larvae and their excrements. For the reasons of sustainability of the state of nature and waste disposal, polystyrene foam was added to the experiment as feed. The experiment was performed in two phases—rearing for 21 weeks and 5 weeks. The nitrogen content was determined using the Kjeldahl method (ISO 1871: 2009), the fat content by the Soxhlet method and the fatty acid profile using a gas chromatograph with a flame ionization detector (FID). The results of the work show that the basis of the TM feed is wheat bran, not only due to the observed low larval mortality (45% over 21 weeks) and their optimal nutritional value (nitrogenous substances 53.6% DM, fat 37.1% DM, the highest total fatty acid content) but also due to the higher speed of TM development. Lower larval mortality during rearing was found when feeding dried whey and raw ware potatoes, but the development cycle rate was low. This confirmed that the bran as a feed allowed a fast life cycle with good larval nutritional parameters. From a nutritional and reproductive point of view, TM appeared to be a suitable alternative to animal production. Polystyrene as a feed, tested for biodegradation by TM larvae, caused the highest larval mortality (75% in 21 weeks). However, the content of nitrogenous substances in the larvae increased to 69.77%, in the excrement, it even increased to 82.68%, and there was no cannibalism among the larvae. The work thus demonstrated the possibility of biodegradation of polystyrene using TM larvae with an increase in nitrogenous substances in both larvae and excrement.

A Way to Increase Protein and Magnesium Content in Dairy Products

The paper describes the results of research devoted to solving such a relevant problem as a lack of protein and its incomplete precipitation when obtaining protein dairy products. The possibility of using magnesium to forfeit coprecipitate with a chelated form of the microelement has been considered. Magnesium deficiency is currently experienced by up to 80 % of the population; the deficiency symptoms are such common problems as cardiovascular system disorders, arrhythmias, angina pectoris, hypertension. Given the urgency of these issues and the growing deficit of magnesium in the diet, the study is devoted to the isolation of whey proteins by thermal precipitation with calcium and magnesium salts to obtain a product containing a high amount of animal protein and the magnesium micronutrient. Optimal salt ratios for more complete precipitation of milk proteins have been determined. Their effect on the protein-free whey parameters, the mass fraction of casein and whey proteins, the content of nitrogenous substances, and the total protein yield has been studied. It is shown that protein coprecipitates obtained by thermal precipitation can be used as a protein additive in the manufacture of fortified dairy products. According to experimental data, it can be concluded that the coprecipitate obtained by thermocoagulation with calcium chloride and magnesium sulfate contains more calcium and magnesium. The product dispersion degree and exposure to proteolytic digestive tract enzymes have been studied. The content of the calcium and magnesium micronutrients in the coprecipitate obtained by thermocoagulation has been determined. It has been proven that this technique allows better using the milk proteins that traditionally pass into the whey.

Tenebrio molitor (Coleoptera: Tenebrionidae)-Optimization of Rearing Conditions to Obtain Desired Nutritional Values.

The present study dealt with the influence of temperature and feed on the nutritional value of Tenebrio molitor, especially on the content of crude protein, amino acids, fat, and fatty acid profile. Tenebrio molitor larvae were kept in 15, 20, and 25°C and fed with wheat bran, lentil flour, and mixture. The parameters were analyzed by international standard methods. Generally, with an increase of the lentils in the feed, the crude protein content increased. The changes in the temperature and the feed were most pronounced on the essential amino acids Val, Arg, and Leu. The highest average fat content was determined at 20°C in insects fed with wheat bran. The lowest fat content was determined at 15°C in bran-fed insects. The dependency of fat content on the temperature in feeding with lentil flour and a mixture of wheat bran and lentil flour was statistically insignificant (P > 0.05, Kruskal–Wallis, Mann–Whitney post hoc tests). The highest content of polyene fatty acids was achieved at a rearing temperature of 15°C and the bran diet. It was concluded that a higher proportion of protein diet could increase the content of crude protein in the insects. An increase in the temperature generally leads only to a slight increase in the content of nitrogenous substances. The influence of feed on this nutritional parameter is therefore much more significant than the effect of the rearing temperature. In general, it can be stated that the feed and the temperature also significantly affect the fat content.

Влияние условий замачивания ячменя на содержание белковых веществ в солоде

Introduction. Malt production requires low-protein barley. Unfortunately, bad environmental conditions often lead to higher protein content than specified in the related standards. The research objective was to study the effect of barley steeping conditions on the level of albuminous substances in malt and to assess the possibility of reducing nitrogenous substances by changing the steeping regime. 
 Study objects and methods. The research featured two varieties of barely, namely “Primorsky 89” and “Primorsky 98”. Both varieties were harvested in 2013, 2015, and 2016 in the Primorye Region of Russia. The protein content in the grain of each variety differed significantly, depending on the year of harvest, and ranged from 1.75% to 2.5%. Two micromalting modes differed only in the steeping time and were performed at 17°C. The malt samples were analyzed for total protein content, total soluble nitrogen, Kolbach Index, and free amino nitrogen. 
 Results and discussion. The “Primorsky 89” variety proved insensitive to a longer steeping time, thus maintaining the same characteristics of the malt. The decrease in the protein level in the malt compared to the raw material was approximately the same for each mode and amounted to 0.3%. The Kolbach Index ranged between 30.31% and 35.1%. The experiment failed to produce the desired degree of dissolution, while the difference in this indicator under various modes was less than 1%. The long steeping mode proved optimal for the “Primorsky 98” variety. An increase in the steeping time made it possible to reduce the content of nitrogenous substances in the malt by 1%, compared to the raw material. Higher initial protein content in the grain resulted in lower content of nitrogenous substances during malting. The long steeping mode also resulted lowered the Kolbach Index by 3%: it was 34.7% – 39.5% for the long steeping mode and 31.1–36.8% for the short steeping mode. 
 Conclusion. The barley variety and the malting method affected the dynamics of nitrogenous substances. For some varieties, a longer steeping period proved to reduce the content of nitrogenous substances in the malt and increase the Kolbach Index.

System for the evaluation of malting quality of wheat varieties

A new system for the calculation of malting quality of wheat varieties was designed. The malting parameters affected by a variety more than by a year or a site were used in the system. These parameters include wort viscosity, soluble nitrogen content, free amino nitrogen content, diastatic power, final attenuation of wort, and extract of malt. The system was used to assess the malting quality in 38 wheat varieties. The point value of each parameter was calculated using the regression equations, and the total value of the malting quality of wheat was determined by the modified “superiority measure” method. The results of the assessment of the wheat malting quality showed considerable differences between the varieties. Several varieties exhibited a more pronounced tendency to accumulate nitrogenous substances in grain. Some varieties, even with a slightly higher content of nitrogenous substances, provided above average malt quality. The set included the varieties that exhibited the optimal content of nitrogenous substances in grain, yet they did not give malt of good quality. Spring wheat varieties Alondra, Anabel, and Seance achieved significantly above average malting quality. Dagmar, Evina, Sultan, Rumor, Sailor, and Brokat exhibited slightly above average malting quality. The proposed system for monitoring malting quality of wheat varieties can help find the varieties suitable for the production of quality wheat malt.

A gravimetric method for the quantitative determination of soluble β-glucan content in oat grain

Background. Oat (Avena sativa L.) is one of the most important sources of protein, oil, starch and dietary fibers, in particular β-glucans. Dietary fiber serves as a source of nutrition for the intestinal microflora and significantly affects not only its composition, but also the normal functioning of the intestine as a whole. In connection with the increased interest in β-glucans as a food component and dietary supplement, there is a need in a convenient and inexpensive method for determination of β-glucans content in grain. The article provides an overview of the existing methods for the isolation and determination of soluble β-glucans in cereals: enzymatic, alkaline, alkaline-enzymatic, colorimetric; their advantages and disadvantages are noted. The main disadvantages of some methods are the complexity and duration of execution, significant cost of the required reagents, and the inability to determine the exact content of β-glucans due to their insufficient purification from various impurities.Results. This study used the example of naked and covered oat cultivars to demonstrate applicability of the gravimetric method that we developed by modifying the alkaline method. Whole grain oat flour was pretreated with a 50% ethanol solution to inactivate β-glucanase and remove free sugars, some lipids, proteins, and other substances. β-glucans were released from the aleurone layer and the endosperm with a 5% sodium hydroxide solution, and finally extracted with a 70% ethanol solution. Β-glucans floated to the surface in the form of a bunch of fibers, which was then dried at a temperature about 100-102°C to constant weight and weighed. The content of β-glucans was calculated from the dry weight (%). The isolated β-glucans were checked for the presence of accompanying substances: the content of nitrogenous substances was determined by the Kjeldahl method, and the presence of starch was determined by a qualitative reaction with Lugolʼs reagent.Conclusions. The content of β-glucans in the grain of the studied samples ranged from 3.12±0.18 up to 4.65±0.17% of the dry weight. As a result of the study, the optimal conditions of β-glucans isolation were selected: the extraction mixtures ratios, as well as the modes of centrifugation, sedimentation and drying were established. It has been shown that this method makes it possible to isolate β-glucans with a minimum impurity of nitrogenous substances (0.07-0.12%) and no traces of starch. One of the advantages of the described method is its availability for mass analysis when studying a collection of grain crops.

Effect of the timing of water deficit on the must amino acid profile of Tempranillo grapes grown under the semiarid conditions of SW Spain

Must nitrogen is very important for successful fermentation. Irrigation can influence vine nitrogen availability, and therefore must nitrogen content and wine quality. The aim of this work was to assess the effect of vine water status on the nitrogen concentration of cv. Tempranillo grown under semiarid conditions. A rainfed and two regulated deficit irrigation (RDI) strategies, late (LDI) and early deficit irrigation (EDI) were applied during pre- and post-veraison respectively periods over two seasons in Badajoz (Spain). Twenty-eight amino acids, amines and ammonia were determined by high performance liquid chromatography (HPLC) in the must. Results showed an effect of the pre-veraison vine water status on the must amino acid concentration. Higher values of nitrogenous indices were reached in musts from LDI treatments, mainly in the dry year. Significant correlations between pre-veraison stem water potential and 19 amino acid concentrations were observed. Therefore, LDI was a more suitable strategy for increasing the content of nitrogenous substances in the must.

Kvalita zrna sladovnického ječmene v České republice, sklizeň 2017

The quality parameters of 277 samples of malting barley from crop 2017 were assessed according to the standard CSN 46 1100-5. The average content of nitrogenous substances was 12.2% and starch content 62.6%. Sieving fractions over 2.5 mm achieved the average value of 88.2% and average germination capacity was 98.6%. Average content of grain admixtures unusable for malting was 1.7% and admixtures partly unusable for malting 5.2%.

Sladovnická kvalita odrůd ozimé pšenice (Triticum aestivum L.)

In the course of three testing years (2013 – 2015), a set of 243 winter wheat samples (27 varieties from three testing sites) were analyzed. Basic technological parameters, and some special characters (wort color, color after boiling, wort haze, polyphenol content and dimethyl sulfide precursors) were studied. Winter wheat varieties gave sufficiently high extract contents, the average value of this parameter was 83.5% at the average content of nitrogenous substances of 11.6%. Final attenuation was low (79.8%). Proteolytic modification given by the value of Kolbach index was on average 35%. Content of soluble nitrogen was 704 mg/100 g, of which ca 14% was made up by free amino nitrogen. Cytolytic modification was evaluated mainly by wort viscosity (1.864 mPa.s). Malt friability and β-glucan content in wort were very low. Average arabinoxilan content in wort varied about 1524 mg/l.

Исследование влияния ферментации сахарины японской на химический состав комбикормов для молоди трепанга

Enzymatic processing of laminaria Saccharina japonica by industrial enzymes of proteolytic, mixed and amylolytic (cellulosolytic) action (CelloLux-F, Viscoflu MG, Allzyme РТ, Allzyme Vegpro, and Allzyme BG) is investigated. Alginase activity of enzyme preparations was measured by spectrophotometry with an anthrone reagent. Chemical composition of algae and fodder was determined by standard research methods. Total content of nitrogenous substances in the raw materials was determined by Kjeldahl method on the Kjeltec auto 10 SO Analyzer (Tecator, Japan). Alginic acid content was determined by titration method. Total lipid content was determined by Blight-Dayer method. The content of easily hydrolysable polysaccharides was determined by titration according to Bertrand. In the experiment, CelloLux-F had the highest alginase activity and Allzyme РТ had the lowest activity. Activity of other enzymes lowered in the order: Viscoflu MG > Allzyme BG > Allzyme Vegpro. The alginase activity of enzyme preparations determines their concentrations necessary for hydrolysis. Following to recommendations of the enzyme preparations manufacturers and cited information on their usage, the raw alga materials was processed during 6 hours under pH 6, gm 1 : 10-1 : 12 and temperature 55 о C and 60 о C. Under the processing, the main changes occur in quantitative composition of carbohydrates, namely the alginic acid content is reduced in 17.2-25.3 %, the fiber content is reduced in 38.5-74.0 % and the amount of easily hydrolyzable carbohydrates is increased in 2.7-3.7 times. Degree of the polysaccharides hydrolysis after processing with different enzyme preparations has lowered in the order: Allzyme BG (36.9 %) > CelloLux-F (35.5 %) > Allzyme Vegpro (34.6 %) > Viscoflu MG. The fermented algae were introduced into the mixed fodder formula. Using the processed alga instead of natural one allows to increase the content of easily hydrolyzable polysaccharides and to decrease the content of high-molecular polysaccharides as alginic acid and cellulose. Food efficiency of the mixed fodder was examined by biological testing with using pigmented sea cucumber juveniles with weigh 40-90 mg as the test-objects; the testing was conducted on the basis of aquaculture research complex Zapovednoe in the Kievka Bay (northwestern Japan Sea). The mixed fodder with natural laminaria from the Kiyevka Bay was used as a control in examination. Value of the mixed fodder was estimated by gain in body weight of test-objects. The tests showed the 3-5 times higher gains of the sea cucumber juveniles fed by the mixed fodder with fermented laminaria in compare with the control mixed fodder based on unprocessed algae.

Morphological and biochemical blood values of fattening young rabbits

Meat of rabbits is considered to be a valuable dietary product. It is a source of complete protein, minerals and vitamins. It is second only to meat of turkey by the content of nitrogenous substances. It is known the blood composition is a symptomatic reflection of the intensity of metabolic processes that take place in the animal’s body under the influence of certain feeding factors. Testing of new feed additives in animal diets should be accompanied by in–depth blood analysis. Thus, the purpose of this research is to investigate, along with the performance, the effect of feeding different doses of Prebiolact–Cr on the morphological and biochemical blood values of fattening young rabbits. The research was conducted in four groups of young rabbits selected by the principle of analogues. The basic period of the experiment lasted for 42 days; it was divided into six sub–periods lasting for seven days. Animals of the second group, together with complete granulated mixed feed, received Prebiolact–Cr in the amount of 1.5 g, the third – 2.0 g and fourth – 2.5 g per rabbit daily. During this scientific experiment, young rabbits were kept in two–high cage batteries with five animals in each rabbit hutch, females and males were kept separately. Morphological and biochemical blood values were within their physiological norm when prebiotic preparation Prebiolact–Cr was introduced into the diet of young rabbits at the doses of 1.5, 2.0 and 2.5 g per rabbit daily. Prebiolact–Cr dose of 2.0 and 2.5 g per rabbit daily leads to haemoglobin increase by 4.63% in the third group and 9.5% in the fourth group. Studied feed additive at the dose of 1.5 g per head daily causes the increase of segmented neutrophils by 6.1%, reduction of monocytes by 0.9%, compared to the control group. Glucose content in the blood of experimental rabbits increased by 5.9%, 10.3% and 7.4% when the dose of the preparation became higher. Prebiotic preparation facilitates the increase of iron, potassium, calcium, magnesium and phosphorus content in blood and maintains the immune system of rabbits.

VLIV VEGETAČNÍHO STADIA VOJTĚŠKY SETÉ NA CHEMICKÉ SLOŽENÍ A IN SACCO STRAVITELNOST ORGANICKÉ HMOTY

The influence of the stage of maturity of alfalfa on the chemical composition and in sacco digestibility was studied in a laboratory experiment. Alfalfa plants were analysed in 8 vegetation stages harvested in regular intervals before the beginning of bud setting until the fall of blossoms. The contents of nitrogenous substances, fat, crude fibre, ADF, NDF, Ca, P, Na, K and Mg were determined in the samples, and using the in sacco method also the organic matter digestibility in the rumen. Further we assessed the energy content and calculated the N−free extractives (BNLV) value. In some stages the chemical changes were monitored in the whole plant. It was discovered that during vegetation there was a statistically significant increase in the crude fibre content and in the ADF and NDF fractions and a reduction in nitrogenous substances. A strong negative correlation was detected between the stage of maturity of alfalfa and content of crude protein and net energy for lactation (r = −0.97 and r = −0.92, respectively). In the individual stages of vegetation the differences in the content of nitrogenous substances, fibre and fat were statistically significant (P < 0.05). The statistically highest content of crude protein (28.97%) was detected in the first stage before bud setting and the lowest (11.97%) in the stage after the fall of blossoms. Later vegetation also had a stronger depressive effect on the content of fat and NEL. The organic matter digestibility (P < 0.05) was the lowest in alfalfa in the last stage of sampling (62.6%) when it reached a mere 85.99% of the digestibility at the beginning of bud setting. The highest organic matter digestibility (72.80%) was detected in a sample of young alfalfa prior to bud setting. In the experiment we confirmed a strong and negative correlation (r = −0.97) between the crude fibre content and organic matter digestibility. The correlation was also strong between the stage of maturity of alfalfa and the content of magnesium (Mg).

The effect of applications of various forms of sulfur on the yields and quality of grass forage

The objective of our study was to assess the effect of soil application of sulfur in ammonium sulfate and gypsum and of either soil or foliar application of elemental sulfur on yield of grass forage and its qualitative parameters. The effect of various forms of sulfur on the yields of grass forage and its qualitative parameters was explored in the form of a small plot experiment in the Bohemian-Moravian Uplands in 2004–2006 involving the following variants: 1) sulfur unfertilised control; 2) ammonium sulfate; 3) elemental sulfur; 4) gypsum; 5) foliar elemental sulfur. Sulfurous fertilisers and foliar elemental sulfur were applied to the soil in doses of 40 kg and 8 kg S per ha, respectively. Nitrogen applied in ammonium sulfate was added to all the other variants in the form of ammonium nitrate. Application of the fertilisers was repeated at the beginning of each vegetation season. The stand was cut twice in the course of vegetation. In the harvested biomass we assessed the content of sulfur, nitrogenous substances, and net energy of lactation. The effect of various forms of sulfur on the grass biomass yields was not significant in either of the two cuts. Yields increased after sulfur fertilisation only in the 1st cut, especially after the application of sulfate sulfur and gypsum, and/or after foliar application of elemental sulfur. In the individual years the sulfur content in the biomass gradually increased significantly (0.17–0.23–0.29%). In the first year the sulfur content did not reach the critical deficiency limit (0.2%). Sulfur fertilisation increased the S concentration in grass forage in all the fertilised variants; the highest S content was detected in the variant where gypsum was applied (0.27%). No significant correlation was established between the values of water-soluble sulfur in the soil and the sulfur content in grass forage. Sulfur fertilisation had no significant effect on the N/S ratio, but was the highest in the variant not fertilised with sulfur and the lowest in the gypsum variant. The content of nitrogenous substances and net energy of lactation were significantly the highest after fertilisation with elemental sulfur and was related, among others, to the lowest yields of this variant. Sulfurous fertilisers did not significantly affect the exchangeable soil reaction and the highest content of water-soluble sulfur after the 2nd cut was seen in the gypsum-applied variant.

Production process in Salicornia europaea plants as a prospective phototrophic constituent in bioregenerative life support systems

Plant productivity of a common glasswort Salicornia europaea L. was investigated in relation to the type of nitrogen nutrition and as a function of macronutrient concentrations mimicking the mineral composition of human urine. The source of nutrient nitrogen had no substantial effect on productivity of Salicornia europaea. In plants grown on media with amide as a nitrogen source, the content of nitrogenous substances, including glutamic and aspartic amino acids, was higher than in plants grown with nitrate. In plants grown on media with mineral composition analogous to that of human urine, the shoots accumulated Na and K in almost equally high amounts, on the background of high and nearly equal Na and K concentrations in the nutrient media.

Chemical composition of flesh of diploid and triploid population of tench (Tinca tinca, Linnaeus 1758)

The objective of this study was to determine differences in relevant parameters of the basic chemical composition of flesh (descriptors: dry matter – DM, crude proteins – CP, net proteins – NP and net muscle proteins – NMP, fat – F, ash – A) of communal stock of diploid (2n) and triploid (3n) tench (Tinca tinca L.) of the same origin, in relation to sex (F: female vs. M: male) and age (T<sub>3</sub>: 36 months, after overwintering vs. T<sub>3+</sub>: 42 months, after one summer in the pond). Altogether 137 siblings of tench were studied. The basic chemical composition of flesh of 2n and 3n tench of T<sub>3</sub> age was found to be nearly the same. The only significant difference (P < 0.05) was found in DM content in diploids (5.7% higher DM content in females). Marked changes in the basic chemical composition were related to the increasing age of tench: after one summer in the pond (from T<sub>3</sub> to T<sub>3+</sub>) the DM content increased significantly in all groups of tench (by 5.4% in 2n females, P < 0.05; by 6.5% in 2n males, 9.9% in 3n females and by 7.4% in 3n males, all at P < 0.01). The content of nitrogenous substances was found to increase significantly (P < 0.01) in flesh of 2n males: CP by 3.2%, NP by 4.2% and NMP by 3.3% and in flesh of 3n males: CP by 7.0%, NP by 6.6% and NMP by 7.3%. Muscles of 3n females contained 107.3% higher fat content (P < 0.05). The proportion of ash decreased in 2n and 3n by 2.5% and 1.7%, respectively (P < 0.05). The flesh quality of T<sub>3+ </sub>tench after one summer in the pond was higher if compared with that of T<sub>3 </sub>tench after overwintering. Related to the ploidy level, more favourable chemical composition of flesh and more favourable flesh quality were found for triploids of T<sub>3+</sub> age.  

Increasing the purity of polyuronic sorbents

The method of elution ion-exchange chromatography was applied to increase the purity of polyuronic sorbents (apple, carrot and sunflower pectins). The columns is packed with the adsorbent to be purified. Organic solvents e.g., methanol, ethanol and acetone containing HCl are used for the elution at 20, 40 and 50°C. Elimination of mineral substances and nitrogen-containing compounds and an increase in the polyuronic acid content were observed. It was found that efficient purification of pectic substances is possible under the adopted conditions. Partial de-esterification was observed with increase in the pectin purity and the reaction speed was increased by increasing the temperature. Protein—peptide admixtures removed from these pectins, the greatest decrease in the content of nitrogenous substances being observed with carrot pectin.

GROWTH AND ORGANIZED DEVELOPMENT OF CULTURED CELLS. VII. CELLULAR VARIATION

Variation in long‐continued cultures of Haplopappus gracilis and Daucus carota has been investigated. A strain of carrot tissue was isolated that grew with a compact habit, in contrast to the highly friable habit of the parent strain. Its dividing cells were arranged quite differently than in the parent strain. Earlier work had shown that Haplopappus cultures could be reversibly altered in their pigmentation and form, by changing the culture medium. This was confirmed, and it was further shown that pronounced changes in nitrogenous compounds also occurred in response to factors in the medium. However, strains of Haplopappus were isolated which differed persistently from the parent strain, even when they were maintained under the same conditions. The variant strains, grown in the same medium, showed differences in their content of nitrogenous compounds. Stock cultures also changed spontaneously with time with respect to their content of nitrogenous substances. Acriflavine, at low concentration, inhibited the growth and formation of colonics by cells plated on nutrient agar, but, by prolonged exposure to sublethal amounts of the drug, resistant strains were isolated. Certain of the spontaneous variant strains were found to differ from each other and from the parent strain in their chromosome complements in ways that are described and to which the observed changes in morphology and metabolism of the cultures may be attributed. The variations that may occur in the free cells in culture are contrasted with the greater uniformity of the cells as they exist in the plant body.

Growth and Organized Development of Cultured Cells. VII. Cellular Variation

Variation in long-continued cultures of Haplopappus gracilis and Daucus carota has been investigated. A strain of carrot tissue was isolated that grew with a compact habit, in contrast to the highly friable habit of the parent strain. Its dividing cells were arranged quite differently than in the parent strain. Earlier work had shown that Haplopappus cultures could be reversibly altered in their pigmentation and form, by changing the culture medium. This was confirmed, and it was further shown that pronounced changes in nitrogenous compounds also occurred in response to factors in the medium. However, strains of Haplopappus were isolated which differed persistently from the parent strain, even when they were maintained under the same conditions. The variant strains, grown in the same medium, showed differences in their content of nitrogenous compounds. Stock cultures also changed spontaneously with time with respect to their content of nitrogenous substances. Acriflavine, at low concentration, inhibited the growth and formation of colonics by cells plated on nutrient agar, but, by prolonged exposure to sublethal amounts of the drug, resistant strains were isolated. Certain of the spontaneous variant strains were found to differ from each other and from the parent strain in their chromosome complements in ways that are described and to which the observed changes in morphology and metabolism of the cultures may be attributed. The variations that may occur in the free cells in culture are contrasted with the greater uniformity of the cells as they exist in the plant body.