Toxoplasma gondii infections in chickens - performance of various antibody detection techniques in serum and meat juice relative to bioassay and DNA detection methods.

Chickens, especially if free-range, are frequently exposed to Toxoplasma gondii, and may represent an important reservoir for T. gondii. Poultry products may pose a risk to humans, when consumed undercooked. In addition, chickens are regarded as sensitive indicators for environmental contamination with T. gondii oocysts and have been used as sentinels. The aim of the present study was to determine the suitability of commonly used antibody detection methods, i.e. the modified agglutination test (MAT), IFAT and ELISA to detect T. gondii-infected chickens. Samples of experimentally and naturally infected chickens were used. The infection state of all chickens was determined by Magnetic-Capture (MC-) real-time PCR (RT PCR). Naturally exposed chickens were additionally examined by mouse bioassay and conventional RT PCR on acidic pepsin digests (PD-RT PCR). Blood serum and meat juice of various sources were tested for antibodies to T. gondii. In naturally infected chickens, there was substantial agreement between the mouse bioassay and MC-RT PCR or the mouse bioassay and conventional PD-RT PCR. PD-RT PCR was slightly more sensitive than MC-RT PCR, as all (26/26) bioassay-positive chickens also tested positive in at least one of the tissues tested (heart, drumstick). By MC-RT PCR, 92.3% (24/26) of the naturally infected bioassay-positive chickens were positive. The diagnostic sensitivity of MC-RT PCR was clearly related to the organ examined. Based on a quantitative assessment of the MC-RT PCR results in experimentally infected chickens, brain and heart tissues harbored an at least 100 times higher parasite concentration than breast, thigh or drumstick musculature. In naturally infected chickens, only three out of 24 birds, which were MC-RT PCR-positive in heart samples, also tested positive in drumstick musculature. Under experimental conditions, the agreement between MC-RT PCR and the serological techniques revealed 100% diagnostic sensitivity and specificity. Under field conditions, examinations of sera by ELISA, IFAT and MAT showed good performance in identifying chickens that were positive in either a mouse bioassay, MC-RT PCR, or PD-RT PCR as illustrated by diagnostic sensitivities of 87.5%, 87.5% and 65.2%, respectively, and diagnostic specificities of 86.2%, 82.8% and 100%, respectively. The examination of meat juice samples from breast, drumstick or heart musculature revealed similar or even better results in the ELISA. The results in the MAT with meat juice from breast musculature were less consistent than those of ELISA and IFAT because a number of negative chickens tested false-positive in the MAT. The MAT performed similar to ELISA and IFAT when applied to test meat juice samples collected from heart, thigh or drumstick musculature.

[Occupational skin cancer : Prevention and recommendations for UV protection as part of the treatment approved by the public statutory employers' liability insurance]. / Beruflicher Hautkrebs : Prävention und UV-Schutzempfehlungen im berufsgenossenschaftlichen Heilverfahren.

In Germany, approximately 2 to 3 million employees work in outdoor professions. They are exceptionally exposed to solar ultraviolet (UV) radiation for a large part of their daily working time. Cumulative UV exposure is associated with a significantly increased risk of skin cancer for outdoor workers from various occupational groups (e. g. landscape and horticulture, agriculture and forestry, fisheries and seafaring, construction and trade, as well as sports teachers, lifeguards and mountain guides). Since 1 January 2015, squamous cell carcinoma and multiple actinic keratosis due to natural UV radiation can be recognised as occupational disease No. 5103 by the German statutory social accident insurance. Reducing cumulative UV exposure is the main prevention aspect of this type of skin damage. Therefore, technical, organisational and personal UV protection measures should be implemented in the professional and private environment. Moreover, they have to be regularly used in an appropriate way. In addition to guideline-oriented therapy, training and counselling of patients with already existing actinic skin damage or a recognised occupational disease No. 5103 is therefore of particular importance. The focus should be on improving the individual UV protection behaviour. This article gives an overview of current recommendations for UV protection in the professional environment. It outlines possible solutions for patient counselling in terms of UV protection in everyday practice.

High seroprevalence of Toxoplasma gondii and probability of detecting tissue cysts in backyard laying hens compared with hens from large free-range farms.

Serological assays are commonly used to determine the prevalence of Toxoplasma gondii infection in livestock, but the predictive value of seropositivity with respect to the presence of infective tissue cysts is less clear. The present study aimed at the identification of seropositive and seronegative free-range laying hens from organic and backyard farms, and the relationship with the presence of viable tissue cysts. In addition, potential risk and protective factors on the selected farms were investigated. An in-house T. gondii surface antigen (TgSAG1, p30, SRS29B) ELISA was validated with sera from experimentally infected chickens and used to examine 470 serum samples collected from laying hens from large organic and small backyard farms at the end of their laying period. A total of 11.7% (55/470) of all chickens tested positive, and another 18.9% (89/470) of test results were inconclusive. The highest seroprevalences were observed on small backyard farms with 47.7% (41/86) of chickens being seropositive while another 20.9% (18/86) of test results were inconclusive. Twenty-nine seropositive, 20 seronegative and 12 laying hens which yielded inconclusive ELISA results, were selected for further examination. Hearts and limb muscles of these hens were examined for T. gondii tissue cysts in a bioassay with IFNÉ£-knockout or IFNÉ£-receptor-knockout mice. Viable T. gondii was isolated from 75.9% (22/29) of the seropositive, 25.0% (3/12) of the inconclusive, and 5.0% (1/20) of the seronegative chickens. All 26 chickens tested positive in heart samples, while drumstick muscles (i.e. limb muscles) tested positive only in three. Data on putative risk and protective factors were collected on the farms using a standard questionnaire. Generalised multilevel modelling revealed farm size, cat related factors ('cats on the premise', 'cats used for rodent control'), hen house/hall related factors ('size category of hen house/hall', 'frequency category of cleaning hen house/hall', 'service period') as significantly associated with seropositivity to T. gondii in hens. The final model, which included the age of the birds as an effect modifier and farm as a random effect variable, revealed that the use of cats for rodent control and an area available per hen in the chicken run of ≥10sqm were statistically significant risk factors for T. gondii seropositivity. Overall this study showed that exposure to T. gondii is common in small backyard farms but is rare on large organic farms with a high density of free-range hens, even when cats were present on the premises.

Persistence of Toxoplasma gondii tissue stages in poultry over a conventional fattening cycle.

Toxoplasma gondii is a widely spread protozoon in humans, mammals and poultry. Regarding the latter, nothing is known yet about the duration of T. gondii persistence and distribution over a conventional fattening cycle of turkeys and chickens. Twenty-four turkeys and 12 broiler chickens were infected intravenously with 1×10(6) T. gondii tachyzoites (strain NED). Serum antibody levels were determined weekly by ELISA (turkeys) or immunofluorescent antibody test (chickens). Turkeys were slaughtered at 4, 8, 12 and 16 weeks post-infection (p.i.), and chickens 5 or 10 weeks p.i. (n = 6 per group). Sixteen different tissue samples per bird were analysed for T. gondii by PCR. All infected animals showed seroconversion. In turkeys, 15.9% of all samples were tested positive for T.-gondii-DNA. Among the edible tissues (drumstick, thigh, breast muscle, heart, liver and gizzard) 7.8% tested positive. Among poultry slaughtered after different periods of time after infection no significant differences (P>0.05) regarding the number of positive samples were observed. Only 4 out of 192 samples (2.1%) from infected chickens contained detectable T. gondii DNA.The PCR findings suggested that T. gondii may persist in poultry. Particularly in turkey it was shown that edible tissues stay infected for at least 16 weeks p.i. which indicates a potential risk for consumers of undercooked turkey meat whereas chickens appear less susceptible to T. gondii infection.

Effects of pH, sodium chloride, and curing salt on the infectivity of Toxoplasma gondii tissue cysts.

Toxoplasma gondii is one of the most common zoonotic parasites in the world. The parasite causes no or mild symptoms in immunocompetent humans. However, a high potential hazard exists for seronegative pregnant women and immunocompromised patients. The consumption of meat containing tissue cysts or oocyst-contaminated vegetables and fruits or the handling of cat feces poses a high risk of infection with T. gondii. It is known that raw minced meat, raw fresh sausages, and locally produced raw meat products are possible causes of T. gondii infection. The infectivity of T. gondii tissue cysts in meat products depends, among other factors, on the pH and the salt concentration. Therefore, the impact of these two factors on the tissue cysts was examined. For this purpose, dissected musculature and brain from experimentally infected mice (donor mice) were placed in a cell culture medium (RPMI 1640). The medium was adjusted to different pH values (pH 5, 6, and 7) with lactic acid and to different salt concentrations (2.0, 2.5, and 3.0%) with sodium chloride (NaCl) or nitrite-enriched curing salt (NCS) for the various tests. After storage at 4°C for different time periods, the materials were fed to bioassay mice. Later, the brains were examined for presence of T. gondii to assess the infectivity. The data show that T. gondii tissue cysts have a high pH tolerance. Cysts were infectious in the muscle for up to 26 days (pH 5). In contrast to their tolerance to pH, cysts were very sensitive to salt. Muscle cysts survived at an NaCl concentration of up to 2.0% only, and for no longer than 8 days. At NaCl concentrations of 2.5 and 3.0%, the cysts lost their infectivity after 1 day. When NCS instead of NaCl was used under the same conditions, T. gondii muscle cysts retained infectivity for only 4 days at 2.0%. Consequently, NCS (NaCl plus 0.5% nitrite) has a stronger effect on T. gondii cysts than does common table salt. Sausages produced with low NaCl concentration and short contact times pose a potential risk for susceptible individuals.

Experimental Toxoplasma gondii oocyst infections in turkeys (Meleagris gallopavo).

Toxoplasma (T.) gondii is a protozoan parasite with a broad range of intermediate hosts. Humans are often infected by ingestion of tissue cysts in raw or undercooked meat or meat products. Turkeys as food-producing animals can also serve as intermediate hosts. The aim of the present study was to investigate occurrence and predilection sites of T. gondii infection in turkeys after oral infection with oocysts. Experimental infections with different doses of T. gondii oocysts were performed in 36 turkeys to mimic natural infection. Systemic distribution of parasitic stages was investigated by screening 14 different tissues including the edible tissues heart, liver, thigh, breast and drumstick muscle. Parasite detection was based on a conventional nested polymerase chain reaction (PCR). Animals were sacrificed 6-12 weeks after infection. Results demonstrated parasite spreading over the whole organism after oral infection by oocysts. Most frequently affected tissues were brain (47.2% of all brains were positive for T. gondii) and thigh muscle (25.0% positive samples). Other muscles were regularly T. gondii-positive, all other sampled tissues were positive at least once. Thus, edible tissues are one of the predilection sites of T. gondii in turkeys which renders raw or undercooked turkey meat a potential risk for parasite transmission to humans. Data were compared to results from previous parenteral turkey infections with tachyzoites. With the exception of brain, liver and breast muscle affection, no significant differences were observed between both infection routes. Both infection models could be used for research purposes with certain advantages and disadvantages.

Tissue tropism of Toxoplasma gondii in turkeys (Meleagris gallopavo) after parenteral infection.

Turkeys are known to be natural hosts for the zoonotic protozoan parasite Toxoplasma gondii. The objective of the present study was to gain further knowledge of possible predilection sites of T. gondii infection in this species after parenteral application of tachyzoites. A total of 38 turkeys were infected with different doses of T. gondii tachyzoites. Birds were killed either 6 to 8 or 10 to 12 weeks after the experimental infection. Fourteen different tissues per bird were investigated by a nested polymerase chain reaction (PCR) for the presence of the parasites' DNA. T. gondii DNA was found in any type of tissue analysed; in 86.1 % of all infected birds, at least one sample was tested positive. Over all intravenously infected birds, 15.4 % of all analysed samples contained T. gondii DNA. Most frequently affected tissues were liver (43.3 % positive samples), breast muscle (26.7 % positive samples) and heart (20.0 % positive samples), while the brain was less frequently positive (6.7 %). The number of positive tissues varied from zero to seven tissues per animal with at least one T. gondii-positive edible tissue sample in 80 % of all intravenously infected birds. Still, the results did not indicate defined target tissues or a cyst distribution pattern. Nonetheless, edible organs were most frequently parasitised. The number of positive findings did not differ between the early and the late examination time points. Therefore, a persistence of the tissue stages until the end of the study (12 weeks after infection) is concluded.

Examinations on the prevalence of footpad lesions and breast skin lesions in B.U.T. Big 6 fattening turkeys in Germany. Part II: Prevalence of breast skin lesions (breast buttons and breast blisters).

This project involves the prevalence of breast skin alterations (breast buttons, blisters, purulent bursitis) in male and female fattened turkeys (British United Turkeys Big 6) from conventional intensive farming. In this case, 24 turkey farms across Germany and 11,860 turkeys (5,740 toms, 6,120 hens) were clinically examined, and 16,200 birds (8,400 hens, 7,800 toms) were evaluated on slaughter lines at 7 turkey abattoirs. Each turkey farm included examination of at least 3 consecutive fattening cycles. Especially in the meat examinations, breast skin alterations were a frequent discovery, particularly in the form of breast buttons. The turkey toms exhibited a prevalence of 27.15%, and the toms were affected significantly more frequently (P < 0.001) by these variations than the turkey hens (7.77%). It is possible that the higher BW of the male specimens leads to increased lying times and is therefore connected with more severe strain on the breast region. The increased fattening period of the turkey toms (slaughtering at wk 21 to 22 of life) vs. the female specimens (slaughtering at wk 15 to 17 of life) must be discussed as a cause. Breast blisters and bursitis sternalis were discovered with a prevalence of 7.36 and 1.24% in toms and more seldom in hens, at 0.30% and 0.15%. Large differences in prevalence were partially recognizable between individual farms as well as between the 3 fattening cycles on a farm. Breast buttons and breast blisters are pathological skin variations for which the etiology is multifactorial. Clear correlations between the prevalence of breast skin alterations and the manner of rearing the birds were not able to be determined. An improvement in this situation, which is considered very problematic from the perspective of bird protection and economics, may be achieved only via cooperation to achieve optimized rearing methods, management, and breeding practices.

Examinations on the prevalence of footpad lesions and breast skin lesions in British United Turkeys Big 6 fattening turkeys in Germany. Part I: prevalence of footpad lesions.

The present study demonstrates the prevalence of footpad lesions in turkeys and their level of expression in both live birds and in carcasses. In clinical investigations of 11,860 turkeys (5,740 males, 6,120 females) of the strain British United Turkeys Big 6, individuals of all the observed flocks showed alterations to the plantar skin. In general, the degree and severity of skin alterations were higher in the 16th week of life than in the 6th or 11th week of life. Epithelial necrosis, however, was already apparent in about 45% of individuals in the 6th week of life. At this point, deep lesions on the footpad surface were still rare findings. In the 11th week of life, such skin changes were apparent in 14.7% of males and 25.7% of hens. In general, the feet of male turkeys were less affected by footpad damage than those of females in the subsequent fattening period. In hens, the prevalence of lesions of the footpads at wk 16 of age was 60.0%, almost twice as high as in males of the same age group (33.8%). A comparison of the findings from the right and left feet showed that the state of the 2 extremities was correlated (Spearman correlation: r = 0.830). During the visual inspection of 16,200 slaughtered turkeys (7,800 males, 8,400 hens), almost all carcasses studied showed alterations to the footpad skin. Only 2.1% of males and 0.6% of females were without lesions. The most frequently observed lesions measured up to 2 cm in diameter (males: 59.2%; hens: 57.7%). Pronounced skin lesions of the footpad (males: 21.1%; females: 29.5%) and necrosis of the superficial epithelium (males: 17.5%; females: 12.1%) were less common. Foot abscesses were diagnosed only sporadically (males: 0.1%; females: 0.1%).

Cytosolic and ER J-domains of mammalian and parasitic origin can functionally interact with DnaK.

Both prokaryotic and eukaryotic cells contain multiple heat shock protein 40 (Hsp40) and heat shock protein 70 (Hsp70) proteins, which cooperate as molecular chaperones to ensure fidelity at all stages of protein biogenesis. The Hsp40 signature domain, the J-domain, is required for binding of an Hsp40 to a partner Hsp70, and may also play a role in the specificity of the association. Through the creation of chimeric Hsp40 proteins by the replacement of the J-domain of a prokaryotic Hsp40 (DnaJ), we have tested the functional equivalence of J-domains from a number of divergent Hsp40s of mammalian and parasitic origin (malarial Pfj1 and Pfj4, trypanosomal Tcj3, human ERj3, ERj5, and Hsj1, and murine ERj1). An in vivo functional assay was used to test the functionality of the chimeric proteins on the basis of their ability to reverse the thermosensitivity of a dnaJ cbpA mutant Escherichia coli strain (OD259). The Hsp40 chimeras containing J-domains originating from soluble (cytosolic or endoplasmic reticulum (ER)-lumenal) Hsp40s were able to reverse the thermosensitivity of E. coli OD259. In all cases, modified derivatives of these chimeric proteins containing an His to Gln substitution in the HPD motif of the J-domain were unable to reverse the thermosensitivity of E. coli OD259. This suggested that these J-domains exerted their in vivo functionality through a specific interaction with E. coli Hsp70, DnaK. Interestingly, a Hsp40 chimera containing the J-domain of ERj1, an integral membrane-bound ER Hsp40, was unable to reverse the thermosensitivity of E. coli OD259, suggesting that this J-domain was unable to functionally interact with DnaK. Substitutions of conserved amino acid residues and motifs were made in all four helices (I-IV) and the loop regions of the J-domains, and the modified chimeric Hsp40s were tested for functionality using the in vivo assay. Substitution of a highly conserved basic residue in helix II of the J-domain was found to disrupt in vivo functionality for all the J-domains tested. We propose that helix II and the HPD motif of the J-domain represent the fundamental elements of a binding surface required for the interaction of Hsp40s with Hsp70s, and that this surface has been conserved in mammalian, parasitic and bacterial systems.

Complementary DNAs encoding eukaryotic-type cytidine-5'-diphosphate-diacylglycerol synthases of two plant species.

Cytidine diphosphate (CDP)-diacylglycerol synthase (cytidine triphosphate:phosphatidate cytihyltransferase, EC 2.7.7.41) catalyzes the formation of CDP-diacylglycerol, which is the precursor of phosphatidylinositol, phosphatidylglycerol, and cardiolipin. We report the first cloning, to our knowledge, of two plant cDNAs, StCDS1 and AtCDS1, coding for CDP-diacylglycerol synthase from potato (Solanum tuberosum) and Arabidopsis thaliana, respectively. The two proteins belong to the eukaryotic type of CDP-diacylglycerol synthase and contain eight predicted transmembrane-spanning domains. We analyzed gene expression in shoot and root tissues of potato plants and demonstrated enzyme activity by expression of N-terminally truncated, recombinant StCDS1 in Escherichia coli.

[Percutaneous drainage of renal and perirenal abscesses. 2 case reports]. / Perkutane Drainage von renalen und perirenalen Abszessen. Zwei Falldarstellungen.

Undetected and untreated renal and perinephritic abcesses are associated with high morbidity and mortality rates. Thanks to the technique of ultrasonography and computed tomography, it is now possible to identify a suspected abscess early on. As treatment, percutaneous drainage has proved both effective and associated with only few side effects. Two cases are reported, one with renal, one with perinephritic abscess, both of which were successfully treated with percutaneous drainage.

Toxic quinones produced by mammalian defense cells--causative agents for autoimmune reactions?

Multiple sclerosis is a disease both of the CNS compartment in which a localized immune response occurs, and of the peripheral immune compartment. The causative agent is unknown, though viruses are suspected to be among the candidates. Here a hypothesis is proposed, that apart from viruses, also activated granulocytes of the host might trigger a sensitization against self, insofar as they are suited to modify self-proteins. The modification results from the action of endogenous o-quinones which are generated by activated granulocytes. o-quinones are chemically reactive and couple to proteins producing new epitopes. Modified self-proteins then may sensitize the immune system or break the immune tolerance. Granulocytes thus not only effectively eliminate pathogens, but cause damage to tissues of the host, by proteinases as described in inflammation, or by endogenous o-quinones as proposed here for multiple sclerosis and its models.

[Extracorporeal shockwave lithotripsy in the treatment of pediatric urolithiasis]. / Extrakorporale Stosswellenlithotripsie in der Therapie der kindlichen Urolithiasis.

The 2nd generation lithotripter LITHOSTAR plus was used for extracorporeal shock wave lithotripsy of 9 kidney stones, 2 ureteral calculi and 2 bladder stones in 10 children 15 months to 17 years old. Ultrasonic stone localization was used in 2 children, x-ray guided stone localization in 8 children. General anesthesia was necessary in 6 children. A stone free rate of 60% was achieved after 1 treatment. Except for one 14-year old boy no adjuvant procedures like percutaneous nephrostomy or ureteral stents were applied. No major complications were encountered.

[Extracorporeal shockwave lithotripsy with combined ultrasound and roentgenologic calculus localization. Initial clinical experiences with the Lithostar plus]. / Extrakorporale Stosswellenlithotripsie mit kombinierter sonographischer und röntgenologischer Steinortung. Erste klinische Erfahrungen mit dem Lithostar plus.

Since the introduction of extracorporeal shock wave lithotripsy for non-invasive treatment of renal and ureteral stones, lithotripter units have relied on either fluoroscopic or ultrasound stone localization. While ultrasound stone localization reduces X-ray exposure and facilitates treatment of radiolucent renal stones, fluoroscopic stone localization is superior in the detection of ureteral stones. Since April 1989 we have been using the Lithostar plus, a new lithotriptor system, which provides both fluoroscopic and ultrasound stone localization. After treatment of 108 patients, the initial data suggest that this system combines the advantages of both localization principles, while being as efficient as other second-generation lithotriptor units in bringing about the disintegration of renal and ureteral stones.

Abscisic acid and water transport in sunflowers.

The role of abscisic acid (ABA) in the transport of water and ions from the root to the shoot of sunflower plants (Helianthus annuus) was investigated by application of ABA either to the root medium or to the apical bud. The exudation at the hypocotyl stump of decapitated seedlings was measured with and without hydrostatic pressure (0-0.3 MPa) applied to the root. All ABA concentrations tested (10(-10)-10(-4) mol·l(-1)) promoted exudation. Maximal amounts of exudate (200% of control) were obtained with ABA at 10(-6)·mol·l(-1) and an externally applied pressure of 0.1 MPa. The effect was rapid and long-lasting, and involved promotion of ion release to the xylem (during the first hours) as well as an increase in hydraulic conductivity. Abscisic acid applied to the apical bud had effects similar to those of the rootapplied hormone. Increased rates of exudation were also obtained after osmotic stress was applied to the root; this treatment increased the endogenous level of ABA in the root as well as in the shoot. Water potentials of the hypocotyls of intact plants increased when the roots were treated with ABA at 5°C, whereas stomatal resistances were lowered. The results are consistent with the view that ABA controls the water status of the plant not only by regulating stomatal transpiration, but also by regulating the hydraulic conductivity of the root.

Leucine aminopeptidase in intracytoplasmic membranes of Acinetobacter calcoaceticus.

Cells of Acinetobacter calcoaceticus strain 69-V contain an aminopeptidase that cleaves L-leucine amide, leucylglycine or leucine hydrazide with high efficiency. Leucine 4-nitroanilide and hydrazide are hydrolyzed to less than 0.1% and 1%, resp. of leucine amide. Grown on acetate-NH4+ medium the activity of the enzyme in the cytoplasm is increased 5-fold compared with cells grown on a casamino acid medium or on yeast extract. In these cases the specific activity of the unpurified enzyme is about 5 nkat/mg for the cytoplasmic and membrane-bound enzyme species as well. Up to 30% of the aminopeptidase activity were found mainly in intracytoplasmic membranes, less in cytoplasmic membranes and only traces in outer membranes, presumably as contaminations. It is solubilized by detergents but not by high salt concentrations. An addition of antipain or Z-Ala2-Phe-CH3 before cell rupture did not change the distribution of the enzyme. A mixture of EDTA and 1.10-phenanthroline diminished the membrane-bound enzyme from 11.4% to 4.3% and leupeptin or E-64 increased it to 20%. The enzyme is regarded as leucine aminopeptidase (LAP) bound to intracytoplasmic membranes.

Effect of abscisic acid on the transport of assimilates in barley.

The effect of abscisic acid (ABA) on assimilate transport in barley was investigated in two parallel experiments. First, the effect upon [(14)C]sucrose transport from the flag leaf to the ear of a single ABA application made at different stages of growth of the fruits was investigated; the effect was measured 24 h after treatment. Second, the effect of a single application of ABA made at the same stages of growth as above on grain weight of the mature plant was investigated. In both types of experiments ABA was applied once to the ear of different plants as an aqueous solution (10(-3)-10(-5) M), one to five weeks after anthesis. [(14)C] sucrose was applied by means of agar blocks. Parallel to these experiments, the endogenous content of ABA was investigated in the developing grains. When ears were treated with ABA two or four weeks after anthesis, an increase of up to 70% in the (14)C-transport from the flag leaf to the ear was observed within a 24-h period after treatment (short duration experiments). At these growth stages the endogenous concentrations of ABA were low. In sharp contrast, ABA, especially in a concentration of 10(-3) M, decreased (14)C-import from the flag leaf when applied three weeks after anthesis. At this stage the endogenous ABA content had reached its maximum. Long duration experiments with a single application of ABA to the car two weeks after anthesis resulted in a marked increase of weight per thousand kernels. ABA applications made earlier or later than two weeks after anthesis either reduced the grain weight or had no effect. It is concluded that ABA is involved in the regulation of assimilate transport from the leaves to the grains, possibly by influencing the unloading of sieve tubes in the ears. Promotion or inhibition of assimilate import by exogenously applied ABA may depend on the developmental stage of the grains and on the endogenous ABA level.

[Characterization of a protease from Thermoactinomyces vulgaris (thermitase). 3. Substrate specificity and properties of partially purified thermitase]. / Charakterisierung einer Protease aus Thermoactinomyces vulgaris (Thermitase). 3. Substratspezifität und einige Eigenschaften der teilgereinigten Thermitase.

During the process of cultivation of Th. vulgaris several proteases are formed. In the present investigation the extensively purified major component was used. The substrate specificity was determined by means of 7 proteins, 7 amino acid esters, 5 fatty acid esters and 15 amino acid 4-nitroanilides. Among the protein substrates tested, urea denaturated hemoglobin was split best, followed by gelatin, casein, field bean protein, serum albumin and gluten. The weakest rate of hydrolysis was observed with elastin. In contrast to this acetyl-(L-ala)3-methylester, that is a substrate for elastase, was split best from all the esters tested. Only 8% of this activity could be found with the chymotrypsin substrates acetyl-L-tyr-ethylester and acetyl-L-phe-ethylester and 1% of the above activity with the trypsin substrates tosyl-L-arg-methylester and benzoyl-L-arg-methylester. The fatty acid esters and the p-nitroanilides were hydrolyzed much more slowly. The pH-optimum of thermitase was found in the weakly alkaline region of pH 7 to 9. There were only small differences between the individual high and low molecular substrates. The temperature optimum was between 60 and 75 degrees C for esters and p-nitroanilides as substrates and at 90 degrees C for casein. It should be mentioned that the enzyme was quickly inactivated at temperatures above 70 degrees C.