Showing papers by "University of Hohenheim published in 1990"

Lactic acid bacteria in meat fermentation

Abstract: The main fermented meat products are fermented sausages in which lactic acid bacteria (LAB) are the essential agents of the ripening process. During indigenous fermentations Lactobacillus curvatus and L. sake are the dominating LAB. Their application as starter organisms ensures the dominance of the starter during the whole ripening process. The suppression of the competing fortuitous LAB depends on the quality of the raw materials and on technological factors. The physiological properties of lactic starters do not suffice to ensure a sensory quality which can be found in traditionally produced dry fermented sausages. Additional activities required are present in micrococci and yeasts which, therefore, are further components of starter culture preparations. Some strains of meat-borne lactobacilli exhibit the essential activities like nitrate reductase, nitrite reductase, catalase, lipase, and protease, respectively. To create the optimal starter cultures composed of lactobacilli, these activities have to be studied and optimized in strains of high competitiveness in the fermenting substrate.

Genotypical differences among graminaceous species in release of phytosiderophores and uptake of iron phytosiderophores

Abstract: Graminaceous species can enhance iron (Fe) acquisition from sparingly soluble inorganic Fe(III) compounds by release of phytosiderophores (PS) which mobilize Fe(III) by chelation. In most graminaceous species Fe deficiency increases the rate of PS release from roots by a factor of 10–20, but in some species, for example sorghum, this increase is much less. The chemical nature of PS can differ between species and even cultivars.

Bean pathogenesis-related (PR) proteins deduced from elicitor-induced transcripts are members of a ubiquitous new class of conserved PR proteins including pollen allergens.

Abstract: We have searched for induced transcripts in a cDNA library derived from bean cell suspension cultures treated with an elicitor fromColletotrichum lindemuthianum. Six independently isolated cDNAs corresponding to rapidly induced small mRNAs have been classified by their DNA sequence and slightly different induction behaviour into two groups. 5′- and 3′-untranslated regions exhibit little similarity, but the deduced small acidic proteins designated PvPR1 and PvPR2 are 89% identical. No relationship was found with the well-characterized PR1 proteins from tobacco. However, the PvPR proteins are closely related to pI49 in pea (64% identity), pSTH2 in potato (41 % identity) and PcPR1-1 in parsley (39% identity), which are also induced in response to elicitor or microbial attack. Moreover, a major pollen allergen in birch (Betv1) has a 44% identity with PvPR1 proteins. These similarities establish a ubiquitous class of conserved defense-related proteins and suggest a common yet still unknown function. Southern blot analysis indicates that PvPR protein gene organization is highly complex with an estimated copy number of more than 12 genes.

HPLC separation of DL-amino acids derivatized withN2-(5-fluoro-2,4-dinitrophenyl)-L-amino acid amides

Abstract: Neutral, acidic, and basic protein DL-amino acids (DL-AA) have been separated by HPLC as diastereomeric derivatives obtained after derivatization withN2-(5-fluoro-2,4-dinitrophenyl)-L-alanine amide (FDNP-Ala-NH2, “Marfey's reagent”). HPLC was performed on 3 μm Spherisorb ODS II as the stationary phase with gradient elution using mixtures of triethylammonium phosphate buffer (pH 3) and acetonitrile. The differences in retention times (ΔtR) of diastereomers were compared with those obtained by derivatization of DL-AA with the novel FDNP-reagents FDNP-Val-NH2, FDNP-Phe-NH2, and FDNP-Pro-NH2. FDNP-reagents were synthesized by reaction of 1,5-difluoro-2,4-dinitrobenzene with 0.5 equivalent of the respective L-AA amide in mixtures of aqueous NaHCO3 and acetone at 40–50°C. All FDNP-reagents made possible the resolution of DL-AA. However, FDNP-Val-NH2, gave the largest ΔtR-values in most cases. Large ΔtR-values mainly arise by the formation of an intramolecular hydrogen bond between the carboxy and carboxamide group in the L-L diastereomers and the non-formation of this hydrogen bond in the D-L diastereomer (the first letter refers to the configuration of the AA to be analysed, the second to that of the reagent AA amide) as well as by the low conformational freedom of amino acid residues in diastereomers.

Bacterial starter cultures in food production

Abstract: The scientific approach to bacterial starter cultures has now a history of one century. Dairy science started the application of these cultures and has still the highest standard in culture technology. Progress in substituting the fortuitious food fermentation processes by starters can be observed in meat technology, sour dough production, wine making and fermentation of vegetable juices. However, some processes are still performed by spontaneous fermentation, e.g. vinegar production or sauerkraut fermentation. Lactic acid bacteria are the most important ingredients of starter preparations. The improvement of our knowledge of the physiology, genetics and ecology of the organisms is characteristic for the most recent studies of starter cultures.

Glutamine-Containing Dipeptides in Parenteral Nutrition

Abstract: Of the total pool of muscle free intracellular amino acids, glutamine represents about 60%. During catabolic stress, a marked reduction (50%) of this pool occurs; the depletion is not reversible by therapeutic efforts or conventional nutritional means. If maintenance of the intracellular glutamine pool promotes conservation of muscle protein, there is a theoretical case for use of glutamine supplements in the parenteral nutrition of patients with injury and infection. Glutamine is too unstable and poorly soluble for addition to existing preparations in its native form, but this drawback can be overcome by the use of synthetic stable and highly soluble glutamine-containing dipeptides. In vivo studies in humans and animals provide firm evidence that a synthetic glutamine-containing dipeptide, L-alanyl-L-glutamine (Ala-Gln), is readily hydrolyzed following its intravenous administration. The results also indicate a safe and efficient use of Ala-Gln as a source of free glutamine in parenteral nutrition. In clinical studies, nitrogen balance was more positive in catabolic patients receiving a peptide-supplemented solution than in control patients given isonitrogenous, isoenergetic total parenteral nutrition. Muscle glutamine concentrations were markedly decreased in the control groups. The intracellular concentrations were not influenced following severe injury, but were maintained in postoperative trauma. It is inferred that the increased intestinal requirement and cellular demand for metabolic fuel during catabolic stress is matched by an enhanced demand on muscle glutamine, resulting in intracellular glutamine depletion. Thus, the delivery of adequate amounts of glutamine is essential to maintain the integrity of intestinal mucosa and rapidly proliferating cells, to preserve the muscle glutamine pool, and to improve overall nitrogen economy during conditions of stress.

Growth enhancement by silicon in cucumber (Cucumis sativus) plants depends on imbalance in phosphorus and zinc supply

Abstract: Based on results from water culture experiments with tomato and cucumber plants where severe leaf chlorosis and depression in flower and fruit formation occurred without silicon (Si) supply, Miyake and Takahashi (1978; 1983) concluded that Si is an essential mineral element for these two plant species. Using the same nutrient solution which is high in phosphorus (P) but low in zinc (Zn) we could confirm these results. Severe chlorosis occurred in cucumber when Si was omitted, and the addition of Si prevented these visual symptoms. Simultaneously the concentrations of P drastically decreased in the leaves and the proportions of water extractable Zn increased. Normal growth and absence of chlorosis were, however, also obtained without the addition of Si when either the external concentration of P was lowered or of Zn was increased. Short-term experiments revealed that Si has no direct effect on uptake or translocation of P to the shoot. According to these results, the experimental evidences so far are insufficient for the classification of Si as an essential mineral element for cucumber. Instead, Si may act as beneficial element under conditions of nutrient imbalances, for example, in P and Zn supply and corresponding P-induced Zn deficiency. The mechanism by which Si increases the physiological availability of Zn in leaf tissue is not yet clear.

Physiological role of seminal components in the reproductive tract of the female pig.

Abstract: In many species the appearance of oestrus is sufficient to ensure that the time of ejaculation, sperm transport and capacitation are balanced with the time of ovulation. In the pig these phenomena vary considerably and require additional regulatory mechanisms which are partly explained by seminal components. Boar semen is rich in oestrogens (up to 11.5 micrograms/ejaculate). Infusion of saline with the addition of oestrogens in physiological amounts increased the myometrial contraction frequency up to 2.5-fold. This effect is explained by a release of PGF-2 alpha immediately after oestrogen infusion. Such an infusion also raises peripheral oestrogen concentrations and an effect on LH release can be demonstrated. Additionally, PGF-2 alpha is measurable in uterine vein plasma after oestrogen infusion and is transferred into the follicular fluid. The effect of oestrogens on LH and follicular PGF-2 alpha is likely to contribute to the timing of ovulation in response to mating. A specific protein of Mr 100,000-110,000 has been detected in boar seminal plasma and it exerts a strong immunosuppressive effect. This protein may be involved in a protection of spermatozoa but also of early embryos against female immunological attack. The addition of such specific compounds to AI doses, in which seminal plasma is diluted, may improve prolificacy.

Effect of a Test Meal, without and with Protein, on Muscle and Plasma Free Amino Acids

Abstract: 1. The effect of a protein-free meal and a protein-rich meal on the concentration of free amino acids in plasma and muscle tissue was studied in eight healthy subjects. The energy content of the protein-free meal was 3800 kJ. The protein-rich meal was identical in composition except that 50 g of bovine serum albumin was added. Plasma and samples from the quadriceps femoris muscle (percutaneous muscle biopsy) for amino acid determination were collection before and at 1, 3, 5 and 7 h after the meal. 2. After the protein-free meal the concentrations of most essential amino acids and of some non-essential amino acids in plasma decreased continuously below basal levels at 5-7 h. The muscle concentration of essential amino acids fell too, reaching its nadir 3-5 h after the meal. The decrease in plasma amino acid concentration was smaller than the decrease in muscle concentration for all essential amino acids except phenylalanine. 3. The concentrations of most amino acids in plasma increased transiently 1 and 3 h after the protein-rich meal; histidine and several non-essential amino acids fell below the basal levels at 5-7 h after the meal. In muscle, threonine, valine, leucine, lysine and alanine were increased at 1 and 3 h after the protein-rich meal; isoleucine, serine and glycine fell below the basal level after 5 and 7 h. For the essential amino acids except threonine and lysine, the increase in plasma concentration was greater than the increase in muscle concentration.(ABSTRACT TRUNCATED AT 250 WORDS)

Decrease in nitrate uptake and increase in proton release in zinc deficient cotton, sunflower and buckwheat plants

Abstract: The effect of varied Zn supply on the pH of the nutrient solution and uptake of cations and anions was studied in cotton (Gossypium hirsutum L), sunflower (Helianthus annuus L) and buckwheat (Fagopyrum esculentum Moench) plants grown under controlled environmental conditions in nutrient solutions with nitrate as source of nitrogen With the appearance of visual Zn deficiency symtoms, the pH of the nutrient solutions decreased from 6 to about 5 whereas the pH increased to about 7 when the plants were adequately supplied with Zn In Zn deficient plants the pH decrease was associated with a shift in the cation-anion uptake ratio in favour of cation uptake Of the major ions, uptake of Ca2+ and K+ was either not affected or only slightly lowered whereas NO3 - uptake was drastically decreased in Zn deficient plants Although the Zn nutritional status of plants hardly affected the NO3 - concentrations in the plants, the leakage of NO3 - from roots of Zn deficient plants into a diluted CaCl2 solution was nearly 10 times higher than that of plants adequately supplied with Zn In contrast to Zn deficiency, Mn deficiency in cotton plants neither affected NO3 - uptake nor the pH of the nutrient solution The results indicate that, probably as a consequence of the role of Zn in plasma membrane integrity and nitrogen metabolism, when Zn is deficient in dicotyledonous species net uptake of NO3 - is particularly depressed which in turn results in an increase in cation-anion uptake ratio and a corresponding decrease in external pH The ecological relevance of this rhizosphere acidification is discussed

Aspartic and Glutamic Acid as Ligands to Alkali and Alkaline‐Earth Metals: Structural Chemistry as Related to Magnesium Therapy

Abstract: Magnesium and other alkaline-earth and alkali metals play an important role in the biochemistry of virtually all living organisms. In contrast to “trace elements” these “common metals” are distributed in most cells and tissues, often in considerable concentrations, and a constant supply is indispensable for unrestricted performance of biological functions. In contemporary medicine, various forms of magnesium therapy are recommended in order to compensate for magnesium deficiency due to certain dysfunctions as well as to loss from excessive transpiration. In addition, there are numerous indications for prophylaxis. Magnesium is usually administered orally in the form of “complexes” with “natural” anions derived from I-aspartic, L-glutamic, L-pyroglutamic (pidolic), citric, and orotic acid. Analytical, electrochemical, and spectroscopic investigations of aqueous solutions of these Pharmaceuticals, together with X-ray diffraction studies of crystalline samples, have given a detailed knowledge of these coordination compounds. Only certain combinations can be addressed as magnesium complexes, whereas others are only present as aquo complexes both in aqueous solutions and in the solid state. Thus, a delicate balance of metal complexation and hydrogen bonding exists for the components of the drugs, which is relevant for the metal carrier functions of the organic ligands. Compared with the more flexible stereochemistry of Ca, Sr, Ba, MnII, Zn, Li, Na, and K complexes, which have coordination numbers between 4 and 9, octahedral hexacoordination is found exclusively for magnesium, the most stereoselective of these metals.

Effect of pH and nitrogen source on aluminium tolerance of rye ( Secale cereale L.) and yellow lupin ( Lupinus luteus L.)

Abstract: Soluble aluminium (Al) is a major factor limiting plant growth in acid mineral soils. Aluminium concentrations in soil solutions are mainly determined by soil pH. However, pH also affects the ratio between activities of protons and cationic Al species and the equilibrium between mono-and polynuclear hydroxy-Al species. The phytotoxicity of these species is not yet clear. The objective of the present study was to clarify the role of minor changes of pH in the rhizosphere on Al phytotoxicity in two Al-tolerant plant species by direct control of the pH in the nutrient solution (4.1, 4.3, 4.5) and in addition by varying the pH in the root apoplast using either nitrate or ammonium as N source. The plants were grown in solution culture at constant external pH. Whereas the Al-sensitive plant species barley and horse bean were damaged at very low Al supplies (1.85 μM and 9.3 μM respectively), 222 μM had to be applied to rye and yellw lupin for a comparable inhibition of root elongation. Yellow lupin was initially severely inhibited in root growth by Al, but then gradually recovered from this ‘Al shock’ within 3 days. In contrast to lupin, rye was hardly affected by Al initially, and it took about 16 h until maximum inhibition of root elongation. In the presence of nitrate, raising the pH from 4.1 to 4.5 aggravated root-growth depression by Al in rye and lupin. Whereas rye roots were severely damaged by ammonium especially at low pH, lupin was rather indifferent to the N source. Aluminium toxicity was less severe in presence of ammonium compared to nitrate N. This effect was less clear with rye at lower pH, because of it's higher proton sensitivity compared to lupin. Less Al injury at lower pH and in presence of ammonium was related to lower Al concentrations in the 1 cm root tips. The results are compatible with data showing high phytotoxicity of mononuclear and polynuclear hydroxy-Al species. However, they could also be interpreted in the light of proton amelioration of Al toxicity owing to competition for Al-sensitive binding sites in the root apoplast.

Hypothesis: the effect of oral nitrite on blood pressure in the spontaneously hypertensive rat. Does dietary nitrate mitigate hypertension after conversion to nitrite?

Abstract: Increasing doses of nitrite (3.7-14.8 mg/kg BW) were administered via intragastric intubation to 64 spontaneously hypertensive Sprague-Dawley rats. Systemic blood pressure, measured in conscious animals with the tail cuff method, significantly decreased in a dose-related manner 16 and 32 minutes later, and pulse rate slightly increased. Since orally ingested nitrate may be partially converted to nitrite, it seems worthwhile to study correlations between dietary nitrate and blood pressure in experimental animals and man.

Autofertility and rate of cross-fertilization: crucial characters for breeding synthetic varieties in faba beans (Vicia faba L.).

Abstract: To increase the level and stability of yield in faba beans (Vicia faba L.), heterosis must be exploited. Hybrids are not available because of the instability of male sterility. Synthetic varieties can and should be bred. Thus, we studied the reproductive behavior of this partially allogamous, insect-pollinated crop. Autofertility (AF) and the rate of cross-fertilization (C) were measured in 36 inbred lines and 28 crosses in F1, F2, and F3 generations for 3 years at Hohenheim, Stuttgart, FRG. Heterozygosity strongly increased AF and decreased C. AF was negatively correlated with C. AF varied from 1% to 98%, and C varied from 7% to 82%. Heritability for both characters was high. For an optimum exploitation of heterosis, breeders should utilize lines with high C as variety components. It is often labor-intensive to multiply such lines, due to low AF. Hence, breeders tend to use autofertile lines with rather limited C. We showed that even in this case about 50% of the total heterosis, which equals a yield increase of at least 25% over the inbred line level, is realized. An increase in yield stability due to heterogeneity will occur simultaneously.

Formation of histamine and tyramine by lactic acid bacteria in decarboxylase assay medium

Abstract: A modified decarboxylase assay medium (DCA medium) was used for studying the production of biogenic amines by Leuconostoc oenos DSM 20252 and two strains of Lactobacillus buchneri (Lb14 and St2A). The DCA medium contained histidine, lysine, ornithine and tyrosine as precursors of the respective biogenic amines. Under the experimental conditions both strains of Lact. buchneri produced > 90% of the maximum amount of histamine within 24 h. Only tyramine was produced by Leuc. oenos DSM 20252. accountine for 88% of the maximum theoretical amount within 24 h.

Effects of ileal infusions of nutrients on motor patterns of canine small intestine.

Abstract: In the present study, effects of ileal infusions of nutrients on motor patterns of the proximal small intestine and on gastric emptying were investigated in dogs. An acaloric meal was administered orally, and equicaloric loads of amino acids, oleate, and glucose were infused into the ileum at different doses (0.3, 0.6, and 0.9 kJ/min). The computerized analysis of motor patterns was focused on the differentiation between stationary and propagated contractions recorded by closely spaced extraluminal strain gauges. All three nutrients exerted inhibitory effects on gastric emptying and on contraction force and frequency of the proximal small intestine. Additionally, the propulsive motor pattern induced by the acaloric meal was modulated by reducing the number of contraction waves and their length of spread. All the effects were dose dependent. Among the three nutrients, glucose significantly changed motility at lower doses compared with amino acids and oleate. We conclude that in dogs the ileal brake mechanism is induced by all three nutrients and that it influences not only contraction force and frequency but also the motor patterns of the proximal small intestine.

Extensive sequence similarity of the bean CAD4 (cinnamyl-alcohol dehydrogenase) to a maize malic enzyme.

Abstract: Michael H. Walter, ~ Jacqueline Grima-Pettenati, 2 Claude G r a n d , 3 Alaln M. B o u d e t 2 and Christopher J. Lamb 4 ~ Institut fiir Pflanzenphysiologie -260-, Universitiit Hohenheim, P.O. Box 70 05 62, D-7000 Stuttgart 70, FRG; 2 Centre de Physiologie Vdg~tale, Universit~ Paul Sabatier, 118 route de Narbonne, F-31062 Toulouse Cedex, France; 3 R.A.G.T., B.P. 326, F-12003 Rodez Cedex, France; 4plant Biology Laboratory, The Salk Institute for Biological Studies, P.O. Box 85800, San Diego, CA 92138-9216, USA

Evaluation of the dietary interaction of calcium and phosphorus in the high producing laying hen.

Abstract: 1. In a 6 x 7 factorial experiment using 2688 22-week-old laying hens of the Lohmann-SL strain kept in cages (4 birds/cage), diets containing six calcium (20, 25, 30, 35, 40, 45 g calcium/kg) and seven phosphorus concentrations (3.2, 4.2, 5.2, 6.2, 7.2, 8.2, 16.2 g total phosphorus/kg (Pt)) were combined orthogonally. The resulting 42 treatments were replicated 8 times so that a replicate consisted of a double cage of 2 x 4 hens. The experiment lasted 40 weeks (10 x 28 days). 2. The experimental diets, based on maize and soyabean meals contained 11.5 MJ metabolisable energy/kg and 175 g/kg protein. Different dietary calcium and phosphorus contents were obtained by substituting oat hulls with limestone and dicalcium phosphate. 3. Mortality, egg production, egg weight, egg mass, food intake and food conversion efficiency were determined as well as the breaking strength, thickness of shells and the percentage of eggs with defective shells. 4. All responses measured were significantly influenced by the variance sources (calcium, phosphorus, interaction). Most of the production traits responded asymptotically to increasing dietary phosphorus concentration, the greatest increases or decreases generally being seen between 3.2 and 5.2 g Pt/kg. Further but weaker increases were seen between 5.2 and 8.2 or 16.2 g Pt/kg. 5. Increases in dietary calcium content always resulted in curvilinear responses. In all cases optimal effects were obtained with diets containing 25 g calcium/kg and the worst values at 45 g calcium/kg. The interaction between calcium and phosphorus was recognised by strong performance depressions and a high mortality at combinations of the lowest phosphorus concentration (3.2 g/kg) with high calcium contents (35 to 45 g/kg). These were largely offset by increasing dietary phosphorus. Thus, between 7.2 and 16.2 g Pt/kg and 25 and 45 g Ca/kg a plateau was formed where only small differences in egg production were observed. 6. From the three egg shell characteristics measured, breaking strength and shell thickness responded differently to the percentage of eggs with defective shells. While breaking strength and shell thickness were respectively negatively and positively influenced by increasing dietary phosphorus and calcium contents, both elements affected the proportion of eggs with defective shells.(ABSTRACT TRUNCATED AT 400 WORDS)

Microbial metabolism of quinoline and related compounds. VI. Degradation of quinaldine by Arthrobacter sp.

Abstract: Quinaldine catabolism was investigated with the bacterial strain Arthrobacter sp., which is able to grow aerobically in a mineral salt medium with quinaldine as sole source of carbon, nitrogen and energy. The following degradation products of quinaldine were isolated from the culture fluid and identified: 1H-4-oxoquinaldine, N-acetylisatic acid, N-acetylanthranilic acid, anthranilic acid, 3-hydroxy-N-acetylanthranilic acid and catechol. 3-Hydroxy-N-acetylanthranilic acid was not further metabolized by this organism. A degradation pathway is proposed.

Influence of mating and intra-uterine oestradiol infusion on peripheral oxytocin concentrations in the sow.

Abstract: Oxytocin concentrations were measured radioimmunologically in sows on the day of standing oestrus over a 6-h period (controls, n = 6) or 1 h before and 5 h after mating (n = 5) or transcervical infusion of either 100 ml saline (0.9% (w/v) NaCl, n = 7) or saline plus 10 micrograms oestradiol (simulation of seminal oestrogens, n = 5). In the controls, oxytocin was low, at around 1.0 pmol/l, throughout the investigation period. Similarly, saline infusion did not lead to a noticeable change in oxytocin concentrations in six out of seven sows. In one sow, however, infusion led to a maximum of 86 pmol/l at 1 min after infusion. Oestradiol led to no immediate increase in oxytocin concentrations. Later in the post-treatment period (2-5 h) they were only slightly increased (1 pmol/l vs 3 pmol/l). All mated sows reacted with a rapid and clear increase in oxytocin. Maximal concentrations (42.0 +/- 5.1 pmol/l; mean +/- S.E.M.) appeared 2 min after the onset of ejaculation. Clearly increased concentrations were found for 40 min. It was concluded that mating specifically leads to a rise in oxytocin, probably due to both mechanical and pheromonal stimuli provided by the boar.