Citric Acid Secretion Research Articles

Oxygen and temperature effect on continuous citric acid secretion in Candida oleophila

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Continuous citric acid secretion by a high specific pH dependent active transport system in yeast Candida oleophila ATCC 20177

Continuous citric acid secretion by a high specific pH dependent active transport system in yeast Candida oleophila ATCC 20177

Continuous citric acid secretion by a high specific pH dependent active transport system in yeast Candida oleophila ATCC 20177

Financial support: Part of the work that has been carried out at the Institute of Biotechnology 2 of Research Centre Julich (Germany) was financed by Haarmann and Reimer, a daughter company of the company Bayer, Leverkusen, Germany.

Responses of eucalypt species to aluminum: the possible involvement of low molecular weight organic acids in the Al tolerance mechanism.

Aluminum (Al) tolerance mechanisms in crop plants have been extensively researched, but our understanding of the physiological mechanisms underlying Al tolerance in trees is still limited. To investigate Al tolerance in eucalypts, seedlings of six species (Eucalyptus globulus Labill., Eucalyptus urophylla S.T. Blake, Eucalyptus dunnii Maiden, Eucalyptus saligna Sm., Eucalyptus cloeziana F. J. Muell. and Eucalyptus grandis w. Hill ex Maiden) and seedlings of six clones of Eucalyptus species were grown for 10 days in nutrient solutions containing Al concentrations varying from 0 to 2.5 microM (0 to 648 microM Al3+ activities). Root elongation of most species was inhibited only by high Al3+ activities. Low to intermediate Al3+ activities were beneficial to root elongation of all species and clones. Among the species tested, E. globulus and E. urophylla were more tolerant to Al toxicity, whereas E. grandis and E. cloeziana were more susceptible to Al-induced damage. Although E. globulus seedlings were tolerant to Al toxicity, they were highly sensitive to lanthanum (La), indicating that the tolerance mechanism is specific for Al. Fine roots accumulated more Al and their elongation was inhibited more than that of thick roots. In E. globulus, accumulation of Al in root tips increased linearly with increasing Al concentration in the nutrient solution. The majority of Al taken up was retained in the root system, and the small amounts of Al translocated to the shoot system were found mainly in older leaves. No more than 60% of the Al in the thick root tip was in an exchangeable form in the apoplast that could be removed by sequential citrate rinses. Gas chromatography/mass spectrometry and ion chromatography analyses indicated that root exposure to Al led to a greater than 200% increase in malic acid concentration in the root tips of all eucalypt species. The increase in malate concentration in response to Al treatment correlated with the degree of Al tolerance of the species. A small increase in citric acid concentration was also observed in all species, but there were no consistent changes in the concentrations of other organic acids in response to Al treatment. In all eucalypt species, Al treatment induced the secretion of citric and malic acid in root exudates, but no trend with respect to Al tolerance was observed. Thus, although malate and citrate exudation by roots may partially account for the overall high Al tolerance of these eucalypt species, it appears that tolerance is mainly derived from the internal detoxification of Al by complexation with malic acid.

Correlation between blood plasma levels of free and total testosterone and concentrations of some seminal markers in adult Manchego rams

The purpose of this study was to examine the relationships between blood plasma free and total testosterone (FT and TT) and some seminal markers. Semen ejaculates and blood samples were collected early in the morning at weekly intervals for 2 years from 10 Manchego rams. The semen ejaculated were tested for sperm concentration (SC), seminal plasma samples were analyzed for fructose (F) and citric acid (CA) concentrations and blood plasma samples were assayed for free testosterone and total testosterone concentrations. The relationship between the two types of testosterone and sperm concentration, fructose and citric acid was investigated. The coefficients of correlation between maximum values of free testosterone and total testosterone and the values of fructose, citric acid and sperm concentration, corresponding to 0, 1 and 2, until 13 weeks after testosterone peaks were observed. Plasma testosterone peaked in the second week of September and this week was defined as week 0. Maximum coefficients of correlation between free testosterone and fructose, sperm concentration and citric acid were 0.98 ( P < 0.001), 0.44 ( P < 0.01) and 0.89 ( P < 0.001), respectively. These values were observed to occur following the free testosterone peak after 7 (fructose and sperm concentration) and 5 (citric acid) weeks, between mid-October and early November. Maximum coefficients of correlation between free and total testosterone and fructose, sperm concentration and citric acid were 0.98 ( P < 0.001), 0.24 ( P < 0.05) and 0.82 ( P < 0.001), respectively. These values, like those of free testosterone, were observed to occur following the total testosterone peak after 9 (fructose and sperm concentration) and 11 (citric acid) weeks between mid and late November. Results demonstrate that both free testosterone and total testosterone influence fructose and citric acid secretion even within the breeding season, and that the chemical composition of seminal plasma depends on the type of circulating testosterone that is considered. There were no significant effects of either free testosterone or total testosterone on sperm concentration.

White lupin ( Lupinus albus L.)

White lupin ( Lupinus albus L.) is an annual legume traditionally cultivated around the Mediterranean and along the Nile valley where it is used for human consumption, green manuring and as forage. The composition of the grain and especially the high protein content makes white lupin highly suitable for ruminant diets as a protein-rich product in intensive farming systems. The absence of anti-nutritional factors makes possible a direct on-farm use of white lupin in self-sustained systems. Being mainly self-pollinating, commercial varieties are pure lines bred through pedigree selection. The major diseases are Pleiochaeta setosa for which selection among autumn-sown genotypes was effective, Uromyces lupinicolus causing early defoliation under warm and dry summers and Colletotrichum gloeosporioides (anthracnose). Anthracnose is a major threat because this seed-borne disease induces an early plant death through stem breakage. No genetic resistance is presently available. More breeding effort should be devoted to this disease in the future. Frost tolerance of the autumn-sown crops depends on the root size, the state of the apex and the hardening ability of the vegetative organs. Major improvements were achieved through earlier sowing and through selection of winter hardy genotypes with marked vernalization requirements. The susceptibility of white lupin to high pH and free lime expressed by iron deficiency is due to the root functioning with nutrient uptake under normal conditions enhanced by citric acid secretion. The recent identification of lime- and high pH-tolerant populations offers new possibilities for breeding and for physiological study. The elaboration of the lupin mainstem is described (leaf primordia production and vernalization) and the relationship between mainstem and branches is analyzed. The indeterminate growth habit due to the production of successive branch levels induces late maturation, allows high potential biomass production, but may lead to poor seed yields because of low harvest index. Poor yield stability seems inherent to the indeterminacy. In the autumn-sown background, determinacy under monogenic recessive control strongly modifies the branch structure, separates the vegetative growth and the reproductive growth and results in better yield stability. Determinate cultivars yield well under early sowing conditions because they produce greater biomass, but may then suffer from lodging. Introduction of dwarfism significantly reduces internode length and favors dry matter allocation to the pods. Breeding is now oriented towards the selection of dwarf determinate varieties. Development of molecular biology and transformation techniques offers new prospects in white lupin breeding.

Specific Secretion of Citric Acid Induced by Al Stress in Cassia tora L.

A rapid and sensitive assay method for Al-chelating activity was established to screen Al-chelating substances secreted from roots of Al-resistant species in response to Al stress. From one Al-resistant species, Cassia tora L., an Alchelating substance was detected in the root exudates when they were exposed to SO fM Al in 0.5 mM CaCl2 solution at pH 4.5; the dominant component was identified as citric acid. The secretion of citric acid was very low during the first 4 h after initiation of Al treatment, but increased markedly thereafter. A 3-h pulse with 50 //M Al also induced significant secretion of citric acid after 6 h. The lag between Al addition and secretion of citric acid suggests that inducible processes are involved. A dose-response experiment showed that the amount of secreted citric acid increased with increasing external concentrations of Al. Eight-d treatment of P deficiency did not induce the secretion of citric acid. Exposure to 50 //M of either lanthanum (La3*) or ytterbium (Yb3+) did not induce the secretion of citric acid either. These findings indicate that the secretion of citric acid is a response specific to Al stress in C. tora and constitutes a mechanism of Al resistance.

Starch Hydrolysate, an Optimal and Economical Source of Carbon for the Secretion of Citric Acid by Yarrowia lipolytica (DS‐1)

AbstractUsing Yarrowia lipolytica (DS‐1), secretion of citric acid is studied as a function of carbon sources such as glucose, fructose, hydrol, sucrose, cane sugar molasses, kerosene (all available commercially) and tapioca starch hydrolysate, invert sucrose and invert cane sugar molasses (all prepared in laboratory). On the basis of their acceptability by DS‐1 for citric and isocitric acid secretion, it is concluded that (a) sucrose and cane sugar molasses (with/without inversion) served as poor carbon sources, (b) fructose, hydrol, impure tapioca starch hydrolysate (96 DE w/w) and invert sucrose served as relatively better carbon sources and (c) purified tapioca starch hydrolysate (96 DE w/w) was the best carbon source to substitute glucose by giving comparable (75%) efficiency of conversion and economical advantage.

1,25-Dihydroxyvitamin D3 increases citrate secretion from osteosarcoma cells.

Rat osteosarcoma cells respond to 1,25-dihydroxyvitamin D3 with a 6- to 10-fold increase in the secretion of citric acid. The time required to attain a half-maximal response is 12 h, a time course which is consistent with the postulated steroidal hormone action of this vitamin D metabolite. The citrate response is achieved by physiological concentrations of 1,25-dihydroxyvitamin D3, with half of the maximal response at a vitamin concentration of 0.03 ng/ml. Both the time course and the dose dependence of the citrate response closely parallel the previously reported stimulation of bone Gla protein synthesis by 1,25-dihydroxyvitamin D3 in these cells. Citrate and bone Gla protein bind avidly to bone mineral and are numerically the most abundant organic acid and protein in bone. The parallel secretion of both in 1,25-dihydroxyvitamin D3-treated osteoblastic cells suggests that they may act in tandem to mediate an action of this vitamin D metabolite on the mineral phase of bone.

Dissociation of organic acid secretion from macrophage mediated bone resorption

A prevailing concept in the literature on bone resorption suggests that the removal of calcium crystals from the bone matrix is the result of the secretion of lactic and/or citric acid. In the present study, we have reassessed this concept using an in vitro bone resorption system consisting of thioglycolate elicited rat peritoneal macrophages co-cultured, for up to 96 hours, with devitalized 45Ca-labeled bone particles. In these combined cultures, medium lactate concentration increased linearly for the first 48 hours of culture and remained at a plateau thereafter. Medium citrate concentration, on the other hand, remained constant and at very low levels throughout incubation. In contrast to both citrate and lactate, bone resorption, measured as 45Ca release, began a few hours after the onset of culture and increased at a constant rate for the balance of the 96-hour culture period. Alteration of resorptive activity by the addition of 10−6M cortisol (which stimulates 45Ca release) or the interposition of a filter between cells and bone (which inhibits resorption) was not paralleled by similar shifts in lactate or citrate concentration. These experiments indicate that mobilization of the bone mineral can occur in the absence of a concurrent, generalized release of lactic and citric acid by sesorbing cells. On the other hand, the data do not exclude a possible role for these compounds under circumstances where they are secreteo into a “closed” compartment at the cell-bone interface or, in the case of lactate, during the initial period of resorptive activity.

SYNERGISTIC EFFECTS OF TESTOSTERONE AND OESTROGENS ON ACCESSORY SEX GLANDS AND SEXUAL BEHAVIOUR OF THE BOAR

Summary. The effects of oestrogens on the activity of accessory sex glands were studied in castrated boars receiving testosterone continuously. Diethylstilboestrol (DES), 17\g=b\-oestradiol(E2) and oestrone (E1) were administered successively for 6-week periods which alternated with treatments of testosterone alone. Semen was collected twice each week and measurements were made of the total, the strained and the gel volumes. Citric acid and fructose contents of the seminal plasma were also determined. Highly significant (P<0\m=.\01)differences between boars were observed for all criteria in a series of collections made before castration. Castration resulted in reduction in the total quantities of secretory products of the accessory sex glands. Subsequent treatment with testosterone alone for a period of 12 weeks had only a slight effect on their secretions. Supplementary treatment with DES, E2 or E1 significantly (P<0\m=.\01)increased the secretory activity of these glands from the levels in the respective preceding periods with testosterone alone. After withdrawal of oestrogens, the elevated levels of citric acid secretion remained high or increased further, while the amounts of seminal plasma and fructose continued at the higher levels or declined. Oestrogens also had a synergistic effect with testosterone on improving the libido of castrated boars. The reaction time was decreased by 45% (P<0\m=.\01)during supplementary treatment with oestrone for 12 weeks. The results of these experiments suggest that oestrogens act synergistically with testosterone on the accessory sex glands and on the sexual behaviour of the boar.

The effect of nutrition and androgens on the composition of bovine blood plasma and seminal plasma at puberty.

1. Experiments on three pairs of male identical twin calves have shown that underfeeding at 2.5–6 months of age, i.e. during the critical stage of sexual maturation, considerably delayed the process of puberty, as regards testicular androgen production as well as secretion of fructose and citric acid by the seminal vesicles.2. There was no marked difference in the blood-plasma content of non-protein nitrogen, vitamin A and carotene at 6 months, as between twins on a normal (N) and low (L) plane of nutrition, although the L-twins were growing and maturing more slowly. However, the blood-plasma content of glucose and of most of the free amino acids, was slightly reduced as a result of underfeeding.3. When at the age of 6 months two twin-pairs were castrated and injected with either testosterone or androstenedione (50 mg every 3rd day, for 2 months), the L-twins of both pairs and the N-twin of one pair grew at a faster rate. Moreover, the concentration of nitrogen in blood plasma increased, the rise being particularly evident in the content of indispensable amino acids. This effect, however, was more pronounced in the N- than in the L-twins.4. Testosterone treatment enhanced libido in the N-twin but not in the corresponding L-twin. Androstenedione had no effect on libido in either the N-twin or the L-twin. Thus, although testosterone and androstenedione both effectively promoted growth and nitrogen metabolism, androstenedione, unlike testosterone, was devoid of androgenic activity.

Role of prolactin in the growth and secretory activity of the prostate and other accessory glands of mammals

Experimental evidence in support of the role of prolactin in the growth and secretory activity of the prostate and other accessory glands of mammals is reviewed. Special attention has been focused on the recent evidences based on the use of chemical indices of secretory activity of the prostate gland. The observed strain differences of the prostate in response to prolactin in rats and the paucity of data in other species is emphasized. The need for studies on mammals with compact prostate gland is stressed. Prolactin synergizes with androgen in stimulating fructose and citric acid secretion by the accessory glands in the Indian palm squirrel. In spite of our basic understanding of the synergistic effects of prolactin, its mechanism of action is still enigmatic. The importance of the use of organ culture techniques in the study of the effects of prolactin has been underscored.

Puberty in Suffolk and cross-bred rams.

Summary. Changes during puberty were studied in the live ram lamb by collecting electro-ejaculates and measuring fructose and citric acid concentration and sperm density and morphology. Fructose and citric acid secretion preceded spermatogenesis. Sperm motility improved with decreasing numbers of abnormal spermatozoa. Observations are included on the separation of the penis from the prepuce. In addition, the influence of season of birth on lamb ejaculates was studied. Reproductive development in lambs born in late summer was delayed, androgen secretion being more markedly affected than spermatogenesis. The results of these studies support the view that the onset of male puberty coincides with the time when the testes become androgenically active, the accessory glands begin to secrete fructose and citric acid, and the animal exhibits characteristic male behaviour.

BENZOIC ACID DERIVATIVE IN THE SECRETA OF THE GENITAL EPITHELIUM OF THE COW.

The secretion of citric acid by the bovine female genital epithelium has been investigated by Gaspar & Cseh (1963). In 60% of cases no citric acid was present, but in the secreta of 40% of the cows, quantities corresponding to spots of 1 ·5 to 40 μg could be demonstrated. In 30% of the investigated cases one unidentified spot, usually accompanied by citric acid and showing Rf values from 0·78 to 0·80, also appeared on the chromatogram. We have been trying to identify more closely the compound forming this spot. It was diffusible and remained unhydrolysed in 1 n-sulphuric acid for 2 hr and was in character acid. Although the unknown compound was generally accompanied by citric acid, it could not be identified either with lactic acid, pyruvic acid and the components of the

Effect of nutrition on the onset of male sex hormone activity and sperm formation in monozygous bull-calves.

The effect of a reduced food intake on the onset of androgenic activity and the appearance of spermatozoa was studied in maturing bull-calves. Three pairs of identical twin-calves were used. In each instance, one twin was reared on a ‘high plane’ of nutrition, consisting of normal feeding, and the other on a ‘low plane’ of reduced food intake. Semen was collected from the twin-calves by the electric stimulation method, and analyzed for sperm density, fructose and citric acid. The appearance of fructose and citric acid in semen was taken as an indicator of the onset of secretory function in the seminal vesicles, which depends on the presence of the male sex hormone. Fructose and citric acid appeared in electrically-discharged semen from the normally fed bull-calves several months before the first spermatozoa. This suggested that the male sex hormone began to act in the young animal several months before the appearance of the first spermatozoa. Restriction of food intake had a marked delaying influence on the onset of fructose and citric acid secretion, and a smaller delaying effect on the appearance of spermatozoa. The delaying effect of underfeeding on the secretory function of the bull seminal vesicles as reflected in the diminished output of fructose and citric acid, appeared to be the result of an inadequate stimulation of the gonads by the gonadotrophic hormone. Injections of gonadotrophin were found to elicit a prompt appearance of both fructose and citric acid in the semen. Alterations in the composition of semen caused by underfeeding were shown to run parallel to histological changes in the testes and male accessory organs. Low-plane feeding retarded the differentiation of the seminiferous tubules and of the interstitial tissue in the male gonads. The histological changes in the seminal vesicles induced by underfeeding corresponded closely to the diminished secretory output of fructose and citric acid in these glands.

On the presence and role of inositol and certain other substances in the seminal vesicle secretion of the boar.

meso-Inositol was identified as a major chemical constituent of the seminal vesicle secretion in the boar, and isolated in pure crystalline state. The concentration of inositol in the vesicular secretion exceeds considerably the amounts hitherto recorded for material of either plant or animal origin. The fluid secreted by boar seminal vesicles contains 2 to 3 g inositol in 100 ml. The dry matter of the fluid is about 15 g/100 ml., one-third of which is dialyzable; of this between 40 and 70% is composed of inositol. Two methods are described by means of which it is possible to obtain several grams of pure crystalline inositol from the seminal vesicle secretion of a single animal. Certain other characteristic features of the boar vesicular secretion are described, including the occurrence of substances such as fructose as well as an hitherto unidentified carbohydrate, also of ergothioneine and potassium citrate; and an almost complete absence of sodium chloride. One of the functions of inositol and citrate appears to be the maintenance of the osmotic pressure in the seminal vesicle secretion, and probably also in the semen of the boar. The secretion of inositol, ergothioneine, fructose and citric acid, by the seminal vesicles, sets in at an early stage of the development of the boar, a considerable time before the maturation of spermatozoa.

Some metabolic effects of androgenic substances.

IT was previously shown that the secretion of both fructose and citric acid in the male accessory organs of reproduction is governed by, and responds readily to, the fluctuations in the level of the male sex hormone. This close relationship made it practical to use the estimation of fructose and citric acid, either in semen or in the accessory glands, as a 'chemical indicator test' for the male hormone1'2'3. Recently, in the course of a metabolic study of transplants from accessory glands of the rat, it was found that when small pieces of male glands were dissected from young rats and transplanted subcutaneously into male or female hosts, such transplants grew readily in response to testosterone propionate or normally secreted testis hormone, and when fully developed exhibited a high content of fructose and pitric acid4,5.

Secretion of Fructose and Citric Acid in Transplants of Rat Seminal Vesicle and Coagulating Gland.

SummarySubcutaneous transplants of coagulating gland and seminal vesicle in rats, were capable of producing fructose and citric acid when grown a) in normal males, b) castrated testosterone-treated males, and c) testosterone-treated non-spayed or spayed females.