Effect of high-oxygen and high-carbon-dioxide atmospheres on strawberry flavor and other quality traits

The effect of high-oxygen atmospheres on strawberry flavor was studied. Strawberry fruits (Fragariax ananassa Duch. cv. Camarosa) were stored at 8 degrees C in four different atmospheres: air, 5% O(2)/20% CO(2), 80% O(2)/20% CO(2), and 90% O(2)/10% CO(2). Changes in several quality parameters were evaluated. Atmospheres combining high O(2) and high CO(2) were the most effective in preventing fungal growth and enhancing strawberry firmness. Other quality parameters such as color, titrable acidity, sugars and organic acids distribution, off-flavor development, and aroma were only mildly affected by superatmospheric O(2) levels. After one week of storage, unexpected high contents of off-flavor related compounds were found in the 80% O(2)/20% CO(2) and 90% O(2)/10% CO(2) atmospheres. Evidence of an altered ester biosynthesis was also found in fruits stored under these high-O(2) atmospheres. Data obtained suggest that stress induced by high CO(2) and stress induced by high O(2) have an additive effect on strawberry flavor alteration.

Cytosolic aldolase is a ripening related enzyme in strawberry fruits (Fragaria x ananassa)

Two aldolase isoenzymes have been isolated from ripe strawberry fruits (Fragaria x ananassa cv. Camarosa and Elsanta) and partially purified by DEAE anion exchange and Sephacryl size exclusion chromatography. The isoenzymes were identified as class I cytosol and plastid aldolase on the basis of their chromatographic behavior on DEAE-cellulose columns, native molecular weight, pH optimum pattern, Km value for D-fructose-1,6-bisphosphate, tendency to be inactivated by lower pH values and SDS-PAGE subunit determination of 40 and 38 kDa, respectively. Total aldolase activity and distribution of both aldolase isoenzymes was also investigated at different stages of strawberry fruit ripening. Strawberries in the green and white ripening stage showed the same ratio of the two isoenzymes as green leaves with 15 and 8% cytosol aldolase activity, respectively. During strawberry fruit development the overall total aldolase activity decreased until the pink ripening stage and then increased due to a rise of cytosol aldolase yielding up to 75% in red strawberries. A cDNA putatively encoding the cytosolic form of aldolase in strawberry was cloned during the course of this study. Both microarray and RNA gel blot analyses showed that the cytosolic aldolase gene expression is induced during ripening as detected for the cytosolic aldolase enzyme. We suggest that induction of the cytosolic aldolase both at the levels of transcription and translation might be part of a ripening related stress response in the receptacle tissue.

Optimizing headspace temperature and time sampling for identification of volatile compounds in ground roasted Arabica coffee

Equilibration time and temperature were the factors studied to choose the best conditions for analyzing volatiles in roasted ground Arabica coffee by a static headspace sampling extraction method. Three temperatures of equilibration were studied: 60, 80, and 90 degrees C. A larger quantity of volatile compounds was extracted at 90 degrees C than at 80 or 60 degrees C, although the same qualitative profile was found for each. The extraction of the volatile compounds was studied at seven different equilibration times: 30, 45, 60, 80, 100, 120, and 150 min. The best time of equilibration for headspace analysis of roasted ground Arabica coffee should be selected depending on the chemical class or compound studied. One hundred and twenty-two volatile compounds were identified, including 26 furans, 20 ketones, 20 pyrazines, 9 alcohols, 9 aldehydes, 8 esters, 6 pyrroles, 6 thiophenes, 4 sulfur compounds, 3 benzenic compounds, 2 phenolic compounds, 2 pyridines, 2 thiazoles, 1 oxazole, 1 lactone, 1 alkane, 1 alkene, and 1 acid.

A model of the health and economic impact of posttransfusion hepatitis C: application to cost-effectiveness analysis of further expansion of HCV screening protocols

BACKGROUND

Cost-effectiveness analyses are needed to decide the value of further expansion of the screening protocols for HCV in blood donors. However, such analyses are hampered by imperfect knowledge of the health and economic repercussions of posttransfusion hepatitis C (PTHC).

STUDY DESIGN AND METHODS

A Monte Carlo simulation of a Markov model representing the outcomes of patients transfused with HCV-infective blood was used to estimate the health and economic impact of PTHC and to calculate the cost-effectiveness ratio of various HCV screening methods.

RESULTS

Median survival for hypothetical patients with PTHC and for controls without hepatitis was 11.25 and 11.75 years, respectively. Overall, 12.3 percent of patients receiving HCV-infective blood will develop chronic hepatitis, 9.3 percent will progress to liver failure, and 9. 25 percent will eventually die of liver disease after a median time of 20.75 years (range, 6-70). Ninety-one percent of the infected blood recipients had no reduction in life expectancy due to PTHC, and the average loss per patient was 0.754 years. The present value of the lifetime health costs incurred by patients with PTHC is $6330 per case. HCV antibody testing increases the patients' life expectancy by 20.4 hours per blood collection tested, and it results in net savings by decreasing the number of patients that will require treatment for liver disease in the future. Adding HCV NAT increases the patients' life expectancy by 0.08 hours per blood collection tested, at a cost-effectiveness ratio of $1,829,611 per QALY gained.

CONCLUSION

PTHC has low health benefits because of the advanced age of many blood recipients. Testing donors for HCV antibodies results in net savings for the health care system, despite low health benefits. Adding HCV NAT would produce little additional gain at a very high cost.

Photokilling mechanisms induced by zinc(II)-phthalocyanine on cultured tumor cells

The photosensitizing effects of liposomal zinc(II)-phthalocyanine (ZnPc) on HeLa cells, with emphasis on morphological changes and mechanisms for cell death, have been studied. No dark toxicity for ZnPc alone was found. Incubation for 1 h with ZnPc followed by red light irradiation induced a variable decrease in the surviving of cells, which was related to both drug concentration and irradiation time. A lethal photodynamic effect (100% of the cells are killed: LD100) was induced by 5 x 10-6 M ZnPc and 5-min irradiation, whereas a sublethal effect (60% of the cells are killed: LD60) was detected with 10 7 M ZnPc and 3 min of red light. Toluidine blue and Hoechst 33258 staining showed characteristic alterations of cell morphology. Numerous bubbles on the plasma membrane were found immediately after an LD100 treatment, and a necrotic morphology appeared 24 h later. On the contrary, severe cell shrinkage with nuclear fragmentation. characteristic of apoptosis. was observed 8 and 24 h after LD60 treatments. In this case, propidium iodide-acridine orange labeling and the TUNEL assay confirmed the occurrence of apoptosis. The highest amount of apoptotic cells appeared 24 h after LD60 treatments, particularly in detached cells, as revealed by cell counting and DNA electrophoresis. Both apoptotic and necrotic mechanisms for cell death occur in HeLa cells in dependence on the experimental protocol of ZnPc photodynamic treatments.

Specific and rapid induction of the proapoptotic protein Hrk after growth factor withdrawal in hematopoietic progenitor cells

Hrk is a newly described proapoptotic member of the Bcl-2 family that is mainly expressed in hematopoietic tissues and cultured neurons. In this study we have examined the expression and activity of Hrk in hematopoietic progenitors. To address these issues, we used 3 growth factor-dependent murine hematopoietic cell lines, HCD-57, FDCP-Mix, and FL5.12. The expression of Hrk was undetectable in cells cultured with growth factors, but it was rapidly up-regulated on growth factor withdrawal. In contrast, the expression of Bcl-x(L) decreased and that of proapoptotic Bax, Bad, and Bak was unchanged or down-regulated after removal of growth factors. This pattern of expression correlated with the induction of apoptosis. Hrk was also up-regulated in human cell lines and in bone marrow-derived CD34(+) cells cultured in the absence of growth factors. In addition, the levels of Hrk were up-regulated after treatment with the chemotherapeutic drug etoposide. Expression of prosurvival Bcl-x(L) or Bcl-2 proteins blocked the induction of Hrk. Hrk was induced in FDCP-Mix cells treated with ionomicin in the presence of IL-3, suggesting that cytosolic calcium may regulate the expression of this proapoptotic protein. Furthermore, ectopic expression of Hrk induced cell death of hematopoietic progenitors in the presence of IL-3. Thus, Hrk is specifically and rapidly induced in hematopoietic progenitors after growth factor deprivation or treatment with chemotherapeutic drugs, and this may be sufficient to induce apoptosis in these cells. (Blood. 2000;95:2742-2747)

c-Raf regulates cell survival and retinal ganglion cell morphogenesis during neurogenesis

The signaling cascade Ras/Raf/mitogen-activated protein kinases modulates cell proliferation, differentiation, and survival, all key cellular processes during neural development. To better define the in vivo role of Raf during chick retinal neurogenesis, we interfered with Raf-dependent signaling during days 4.5 to 7.5 of embryonic development by expressing a dominant negative mutant of c-Raf (DeltaRaf), which blocks Ras-dependent Raf activation, and by overexpressing wild-type c-Raf. DeltaRaf expression induced an increase in cell death by apoptosis, whereas it did not affect overall cell proliferation and differentiation. In parallel, the number of Islet-1/2-positive and TUJ1-positive retinal ganglion cells were diminished in their definitive layer, whereas there was an increase in the number of mislocated Islet-1/2-positive cells. This disturbed morphogenesis correlated with a disruption of the optic fiber layer. Conversely, c-Raf overexpression caused moderate opposite effects on apoptosis. These results frame in vivo early neurogenesis processes in which c-Raf is essential.

Fourier transform infrared evidence for early deprotonation of Asp(85) at alkaline pH in the photocycle of bacteriorhodopsin mutants containing E194Q

The role of the extracellular Glu side chains of bacteriorhodopsin in the proton transport mechanism has been studied using the single mutants E9Q, E74Q, E194Q, and E204Q; the triple mutant E9Q/E194Q/E204Q; and the quadruple mutant E9Q/E74Q/E194Q/E204Q. Steady-state difference and deconvoluted Fourier transform infrared spectroscopy has been applied to analyze the M- and N-like intermediates in membrane films maintained at a controlled humidity, at 243 and 277 K at alkaline pH. The mutants E9Q and E74Q gave spectra similar to that of wild type, whereas E194Q, E9Q/E194Q/E204Q, and E9Q/E74Q/E194Q/E204Q showed at 277 K a N-like intermediate with a single negative peak at 1742 cm(-1), indicating that Asp(85) and Asp(96) are deprotonated. Under the same conditions E204Q showed a positive peak at 1762 cm(-1) and a negative peak at 1742 cm(-1), revealing the presence of protonated Asp(85) (in an M intermediate environment) and deprotonated Asp(96). These results indicate that in E194Q-containing mutants, the second increase in the Asp(85) pK(a) is inhibited because of lack of deprotonation of the proton release group. Our data suggest that Glu(194) is the group that controls the pK(a) of Asp(85).

Role of diffusible and transcription factors in inner ear development: implications in regeneration

Organogenesis involves a dynamic balance of the mechanisms regulating cell division, differentiation and death. The development of the chicken embryo inner ear offers a well-characterised model at the morphological level to study which signals are implicated in the modulation of cellular activation and commitment. The early developmental decisions that control the origin of the inner ear elements are just beginning to be identified by complementary in vivo and in vitro studies. Insulin-like growth factor-I (IGF-I) and nerve growth factor (NGF) are among the best characterised diffusible factors acting during inner ear development. Although the cellular actions of these factors are beginning to be understood, the signalling pathways triggered by them still remain largely unknown. In this context, viral vehicles can be used to deliver genes and then analyse their functional roles during inner ear development. A model is proposed where the actions of IGF-I and NGF contribute to the combinatorial expression of Jun and Fos family members in particular domains of the otic vesicle. Some of these mechanisms may be also implicated in otic regeneration.

Relative sensitivity of direct antiglobulin test, antibody's elution and flow cytometry in the serologic diagnosis of immune hemolytic transfusion reactions

BACKGROUND AND OBJECTIVE

Current immunohematology practice dictates that serologic diagnosis of immune hemolytic transfusion reactions (IHTR) is based on the finding of a positive post-transfusion direct antiglobulin test (DAT). However, since DAT may fail to detect antibody-coated cells when they constitute a minor population amid a large number of non-sensitized ones, we investigated whether antibody detection in eluates or by flow cytometry is more sensitive than DAT in this context.

DESIGN AND METHODS

Ten samples of red blood cells sensitized with allo- or autoantibodies were diluted in non-sensitized red blood cells to final concentrations ranging from 10% to 0.1%. DAT, antibody detection in eluates, and immunofluorescence by flow cytometry were performed on each mixture.

RESULTS

DAT failed to detect sensitized cells in all but two cases in that only the 10% dilution yielded a positive DAT. Antibody detection in eluates and by flow cytometry was able to detect up to 1% sensitized cells in most cases.

INTERPRETATION AND CONCLUSIONS

Antibody detection in eluates and by flow cytometry is more sensitive than DAT for detecting minor populations of IgG-coated cells. These techniques should be included in the routine investigation of suspected cases of IHTR.

Depression and body fat deposition in Mexican pregnant adolescents

BACKGROUND

The objective of this study was to assess the effect of maternal depressive symptomatology on fat deposition in a group of pregnant adolescents.

METHODS

A case-control study was performed with 85 pregnant women (45 adolescents and 40 adults) who attended a prenatal care course at a teaching hospital in Mexico City. During the second and third trimesters of gestation, a test proposed by Zung was applied to measure depressive symptoms. Weight and skinfolds (i.e., triceps, biceps, suprailiac, subscapular, and thigh) were measured in all women beginning at week 20 of gestation through 4 weeks postpartum. Monthly evaluations were performed.

RESULTS

At the 28th week of gestation, nearly 40% of pregnant adolescents showed scores above the cut-off points in the depression test, while among the adults this proportion corresponded to 15%. In the adolescents, depression status was related to self-esteem. Percentage of body fat in adult women tended to be relatively constant, while in adolescents a tendency toward increased body fat was found. In adolescents, depressive symptomatology and especially lack of self-esteem and weight gain during pregnancy were the variables that better predicted the fat-increment pattern during gestation, while in adults no variable was found that predicted fat deposition.

CONCLUSIONS

Depression status is a risk factor for excessive fat deposition during pregnancy in Mexican adolescents.

Pattern of expression of the jun family of transcription factors during the early development of the inner ear: implications in apoptosis

Jun transcription factors have been implicated in the regulation of cell proliferation, differentiation and apoptosis. We have investigated the relationship between Jun expression and cell death in the developing chicken inner ear. c-jun and junD transcripts were expressed in the epithelium of the otic placode and otic vesicle. c-jun expression was restricted to the dorsal area of the otic pit (stages 14–17), dorsal otic vesicle and cochleo-vestibular ganglion (stages 18–20). junD expression was transient and occurred in the dorsal and upper medial aspects of the otic pit and otic cup, but it was down-regulated in the otic vesicle. A parallel TUNEL analysis revealed that expression of c-jun co-located within areas of intense apoptosis. Furthermore, phosphorylation of c-Jun at serine-63 by Jun amino-terminal-kinases was detected in the dorsal otic pit, otic vesicle and cochleo-vestibular ganglion. c-Jun protein exhibited DNA binding activity, as assessed by gel mobility shift assays. The association between c-Jun and apoptosis was further demonstrated by studying nerve growth factor-induced apoptosis in cultured otic vesicles. Nerve growth factor-induced cell death and c-Jun phosphorylation that were suppressed by insulin-like growth factor-I and by viral-mediated overexpression of Raf, which had survival effects. In conclusion, the precise regulation of the expression and activity of Jun proteins in the otic primordium suggests that it may operate as a fundamental mechanism during organogenesis.

An enzyme-linked immunosorbent assay applicable to screen blood donors for IgA deficiency

BACKGROUND AND OBJECTIVE

In order to build panels of IgA deficient blood donors, an assay is described that is sensitive, inexpensive and easily adaptable to the automated sample processors and turnaround times of blood banks.

DESIGN AND METHODS

We developed a two-step enzyme-linked immunosorbent assay (ELISA) carried out in microwell plates coated with rabbit anti-human IgA antibody. Captured IgA was revealed with the same antibody conjugated to horseradish-peroxidase. The assay was adapted to the automatic pipetting system and ELISA processors used in routine blood donor screening.

RESULTS

The assay sensitivity was 0.1 microg/mL. Intra-assay coefficient of variation (CV) for IgA concentrations between 0.1 and 100 microg/mL ranged from 0.69% to 3.80%. The median interassay CV was 3.05% (range: 1.2-7.9%). Coated plates can be stored frozen for at least 3 months without any loss in performance. The assay takes around 80 min to be performed. By using this ELISA we found 32 IgA-deficient individuals among 20,000 blood donors (prevalence 1:625).

INTERPRETATION AND CONCLUSIONS

The ELISA has a good sensitivity, is reproducible, precise and timesaving. It is easily adaptable to the automated sample processors and operating procedures used in blood banks. This facilitates the building of panels of IgA-deficient blood donors.

Erythropoietin can induce the expression of bcl-x(L) through Stat5 in erythropoietin-dependent progenitor cell lines

Erythropoietin (Epo) initiates its cellular response by binding to the Epo receptor, which triggers the activation of signal transducer and activator of transcription (Stat) 5 protein. Cell culture studies of erythroid progenitors have suggested that Epo functions as a survival factor by repressing apoptosis at least in part through Bcl-x(L), an anti-apoptotic protein of the Bcl-2 family. In this report, we examine whether Stat5 can induce transactivation of the bcl-x gene in response to Epo. Two Epo-responsive progenitor cell lines, HCD-57 and Bcl-2-transfected Ba/F3-Epo receptor (Ba/F3-EpoR-Bcl-2), were used in this study. After Epo stimulation, we observed a correlation between expression of bcl-x(L) and activation of Stat5 as assessed by the expression of oncostatin M, a direct target of Stat5, and the phosphorylation and nuclear translocation of Stat5. Moreover, a Stat binding element in the bcl-x promoter was found to be active in response to Epo, a finding that was further confirmed because mutagenesis of this sequence motif abrogated its promoter activity and overexpression of a dominant negative Stat5 protein blocked transactivation. When DNA-protein binding analyses were performed, we found that Stat5, not Stat1 or Stat3, was the protein bound to the bcl-x promoter in response to Epo. These data suggest that Epo-dependent activation of Stat5 is a transcriptional pathway that can be used by Epo-responsive progenitor cells to induce the expression of bcl-x(L) and consequently to inhibit apoptosis.

Opening the Schiff base moiety of bacteriorhodopsin by mutation of the four extracellular Glu side chains

The quadruple bacteriorhodopsin (BR) mutant E9Q+E74Q+E194Q+E204Q shows a lambda(max) of about 500 nm in water at neutral pH and a great influence of pH and salts on the visible absorption spectrum. Accessibility to the Schiff base is strongly increased, as detected by the rapid bleaching effect of hydroxylamine in the dark as well as in light. Both the proton release kinetics and the photocycle are altered, as indicated by a delayed proton release after proton uptake and changed M kinetics. Moreover, affinity of the color-controlling cation(s) is found to be decreased. We suggest that the four Glu side chains are essential elements of the extracellular structure of BR.

Effects of ozone treatment on postharvest strawberry quality

The effect of ozone treatment on the postharvest quality of strawberry was evaluated. Strawberry fruits (Fragaria x ananassa Duch. cv. Camarosa) were stored at 2 degrees C in an atmosphere containing ozone (0.35 ppm). After 3 days at 2 degrees C, fruits were moved to 20 degrees C to mimic retail conditions (shelf life). The changes in several quality parameters such as fungal decay, color, sugar and acids distribution, and aroma were evaluated during the strawberries' shelf life. Ozone treatment was ineffective in preventing fungal decay in strawberries after 4 days at 20 degrees C. Significant differences in sugars and ascorbic acid content were found in ozone-treated strawberries. At the end of cold storage, the vitamin C content of ozonated strawberries was 3 times that of control fruits. A detrimental effect of ozone treatment on strawberry aroma was observed, with a 40% reduced emission of volatile esters in ozonated fruits.

Biosynthesis of 4-hydroxy-2,5-dimethyl-3(2H)-furanone and derivatives in in vitro grown strawberries

The biosynthesis of 2,5-dimethyl-4-hydroxy-3(2H)-furanone (Furaneol) and its methyl ether and glucoside derivatives has been studied in strawberries. An in vitro system was used for growing this fruit, showing that the presence in the incubation medium of sucrose or hydroxyquinoline hemisulfate has no effect on the bioformation of these compounds. Strawberries in vitro grown showed an increase in furanone content with time, especially between the second and fourth days, to the same extent as field-grown fruits but at a higher rate. Among the precursors added to the incubation medium, D-fructose gave rise to an increase in furaneol and its glucoside derivative of 42. 6% and 26.3%, respectively. D-fructose 6-phosphate seems to be the precursor of furaneol in strawberries since, when present in the incubation medium, it produced an average increase of 125% in all furanones contents with respect to control fruits.

Involvement of insulin-like growth factor-I in inner ear organogenesis and regeneration

The verterbrate inner ear is an excellent model system to study signalling mechanisms in embryonic development. During the last years, insulin-like growth factor-I (IGF-I) has attracted attention in relation to the regulation of inner ear ontogenesis. IGF-I and its high-affinity tyrosine-kinase receptor are expressed during early stages of inner ear development. IGF-I is a powerful mitogen for the otic vesicle, where it stimulates cell-division and mitogenic signalling cascades. Later in development, IGF-I also promotes survival and neurogenesis of the otic neurones in the cochleovestibular ganglion (CVG). The actions of IGF-I are associated with the generation of lipidic messengers and the activation of Raf kinase, which results in the rapid induction of the expression of the proliferative cell nuclear antigen (PCNA) and the nuclear proto-oncogenes c-fos and c-jun. Regulation of organogenesis involves a dynamic balance of the mechanisms regulating cell division, differentiation and death. A model is proposed where this balance is the consequence of the action of IGF-I and NGF, which converge in Raf activation or suppression. The combinatorial expression of jun and Fos family members in particular domains of the otic vesicle would be the final result of such cascade. Some of these mechanisms may be also implicated in otic regeneration.

Strict regulation of c-Raf kinase levels is required for early organogenesis of the vertebrate inner ear

Regulation of organogenesis involves a dynamic balance of the mechanisms regulating cell division, differentiation and death. Here we have investigated the pattern of expression of c-Raf kinase in the inner ear during early developmental stages and the consequences of manipulating c-Raf levels by misexpression of c-raf viral vectors in organotypic cultures of otic vesicle explants. We found that otic vesicles expressed c-Raf and its level remained constant during embryonic days 2 and 3 (E2-E3). c-Raf activity was increased in response to insulin like growth factor-I (IGF-I) and the activation by IGF-I of the c-Raf kinase pathway was a requirement to turn on cell proliferation in the otic vesicle. Overexpression of c-raf in E2.5 explants increased the proliferative response to low serum and IGF-I and blocked differentiation induced by retinoic acid. The increase in c-Raf levels also prevented nerve growth factor (NGF)-dependent induction of programmed cell death. Consistent with these results, the expression of a dominant negative c-Raf mutant potentiated retinoic acid action and decreased the rate of cell proliferation. We conclude that a strict control of c-Raf levels is essential for the co-ordination of the biological processes that operate simultaneously during early inner ear development.

Use of Temporary and Semipermanent Enrichment Objects by Five Chimpanzees

At the Chimpanzee and Human Communication Institute, caregivers provide the 5 chimpanzees who reside there with many different forms of social, food, habitat, and object enrichment. In this study, we examined the chimpanzees' use of both semipermanent and temporary objects. Semipermanent objects included cargo nets, climbing structures, a treat mound, and other objects that were present at the chimpanzees' enclosure throughout the duration of this study. Each day, 50 temporary objects were placed in the chimpanzees' outdoor enclosure or indoor exercise rooms. Frequency of use was examined in 2 conditions: rotated and same. In the rotated condition, temporary objects were replaced with different temporary objects after 3 hr. In the same condition, temporary objects were presented for the entire day. Focal and scan sampling were used to record the chimpanzees' use of enrichment objects. Observers collected focal sample data to record the chimpanzees' initial reaction to objects when entering the indoor exercise rooms, outdoor enclosures, or both at 9:00 a.m. and 1.00 p.m. A total of 35 hr of focal data and 156 hr of scan data were collected over an 8-week period. Temporary object rotation increased the overall frequency of temporary object use both in the initial 15 min of focal sample data and during the following 6 hr of scan sample data for 4 of the chimpanzees. All of these chimpanzees used both semipermanent and temporary objects throughout the day. Each chimpanzee's pattern of use was unique. The results of this study emphasize the importance of temporary object rotation and presentation of both temporary and semipermanent objects to captive chimpanzee environments.

Lipoxygenase and hydroperoxide lyase activities in ripening strawberry fruits

The enzymes lipoxygenase and hydroperoxide lyase have been identified in strawberry (Fragariax ananassa Duch.) var. Camarosa. Their subcellular localization, substrate preference, and product specificity were determined in mature strawberry fruits. The activity of both enzymes was located mainly in the microsomal fraction. Linolenic acid was the preferred substrate for strawberry lipoxygenase, forming 13- and 9-hydroperoxides of this acid in the proportion 70:30. The strawberry hydroperoxide lyase cleaves 13-hydroperoxide of linoleic (13% relative activity) and linolenic (100% relative activity) acids to form hexanal and (3Z)-hexenal, respectively. Both enzyme activities and endogenous content of volatile aldehydes formed by sequential action of lipoxygenase-hydroperoxide lyase were evaluated during strawberry development and ripening. A sequential enzymatic pathway for the formation of green odor compounds in strawberry is proposed.

Endothelin mediated nitric oxide effects in ischemia--reperfusion associated with pancreas transplantation

Formation of nitric oxide (NO) in ischemia-reperfusion (I-R) associated with pancreas transplantation could modulate the inflammatory response. In this sense, previous studies have demonstrated the action of NO on vasoactive substances like prostacyclin or endothelin. The present study was designed to evaluate the contribution of endothelin to the inflammatory events induced by NO in the I-R process associated with pancreas transplantation. For this purpose, pancreatic levels of endothelin, neutrophil infiltration, and prostacyclin were evaluated in an experimental model of pancreas transplantation after inhibition of NO synthesis or after NO inhibition plus addition of endothelin. Results show significant posttransplantation increases in endothelin, neutrophil infiltration, and prostacyclin production. These increases were prevented by NO inhibition. Endothelin administration plus nitric oxide inhibition reversed this effect, resulting in an increase in myeloperoxidase and 6-keto-prostaglandin F1alpha. These results suggest that the proinflammatory effects of NO in I-R associated with pancreas transplantation are mediated by the induction of endothelin generation.

Induction of cell growth by insulin and insulin-like growth factor-I is associated with Jun expression in the otic vesicle

The present report investigates the cellular mechanisms involved in the regulation of cell proliferation by insulin and insulin-like growth factor-I (IGF-I) in the developing inner ear. The results show that insulin and IGF-I stimulate cell proliferation in the otic vesicle. This effect is associated with the induction of the expression of the nuclear proto-oncogene c-jun. The temporal profile of Jun expression coincided with the proliferative period of growth of the otic vesicle. IGF-I promoted the hydrolysis of a membrane glycosyl-phosphatidylinositol, which was characterised as the endogenous precursor for inositol phosphoglycan (IPG). Both purified IPG and a synthetic analogue, 6-O-(2-amino-2-deoxy-alpha-D-glucopyranosyl)-D-myoinositol-1,2-cyclic phosphate (C3), were able to mimic the effects of IGF-I on Jun expression. Anti-IPG antibodies blocked the effects of IGF-I, which were rescued by the addition of IPG or its analogue. These results suggest that the sequence involving the hydrolysis of membrane glycolipids and the expression of c-jun and c-fos proto-oncogenes is part of the mechanism that activates cell division in response to insulin and IGF-I during early organogenesis of the avian inner ear. The implications of these observations for otic development and regeneration are briefly discussed.