First histopathological study in kidneys of rodents naturally infected with Leptospira pathogenic species from Yucatan, Mexico

Objective: To report the renal histological lesions in synanthropic rodents, Mus musculus and Rattus rattus, naturally infected with Leptospira spp., captured in a rural community in Yucatan, Mexico. Methods: Kidney samples of synanthropic rodents were collected from a rural community in Yucatan, Mexico. Polymerase chain reaction was used to detect Leptospira spp. infection. Tissue kidney was fixed in 10% buffered formalin, processed according to the usual techniques for paraffin inclusion, cut and stained with hematoxylin and eosin, and examined using a conventional electronic microscope. Results: A total of 187 rodents were captured. Nine individuals(4.8%) were positive for Leptospira spp. in the molecular analysis. All renal lesions observed in the histopathological study had been reported previously for Leptospira spp. infection. Conclusions: The histopathological lesions are present in the kidneys, plus the results of the polymerase chain reaction confirm that these rodents are true carriers of Leptospira spp.

Evaluation of Multiple-Use Cover Crops under Rainfed during Two Seasons in Yucatan, Mexico

The aim of the study was assessing seven legumes as cover crops during cropping seasons of the years 2000 and 2001 in the central region of the Yucatan. An experimental design of randomized blocks with arrangement of split plots was used;where treatment was the legume, and sub-treatment, was the management of defoliation, 90 days after sowing (DAS) or after harvesting the grain (AHG). Treatments were: short-cycle seed white lima bean (Phaseolus lunatus), long-cycle seed white lima bean (Phaseolus lunatus), cowpea (Vigna unguiculata), dwarf velvet bean (Mucuna pruriens var. utilis), ash velvet bean (Mucuna pruriens var. utilis), sword bean (Canavalia ensiformis) and red rice bean (Vigna umbellata). It was collected data on coverage and biomass production, grain, leaf litter and stubble yields, biomass and relative frequency of weeds, pH, total nitrogen, organic matter (OM), potential anaerobic mineralization of nitrogen (MPAN) and soil CO2 evolution. Coverage varied from 70% to 90%;and biomass from 1900 to 2500 kg·DM·ha-1 at 90 DAS in ash velvet bean (AVB) and sword bean (SB). Stubble yielded from 800 to 2200 kg·DM·ha-1. The SB reached ~3200 kg·DM·ha-1 of grain yield in the first cropping season and it was reduced in the second cropping season. AVB and SB reduced the biomass of weeds from 890 to 780 kg·DM·ha-1. The OM of soil reached 14.9% in AVB. NH4, pH, and soil CO2 evolution remained without significant changes by effect of legumes.

Physicochemical characterization of chia (<i>Salvia hispanica</i>) seed oil from Yucatán, México

A physicochemical characterization of oil from chia seeds was carried out. Proximate composition analysis showed that fat and fiber were the principal components in the raw chia flour. Physical characterization showed that chia oil has a relative density from 0.9241, a refraction index of 1.4761 and a color with more yellow than red units. Chemical characterization showed that chia oil registered an acidity index of 2.053 mg KOH/g oil, a saponification index of 222.66 mg KOH/g oil, a content of unsaponifiable matter of 0.087%, an Iodine index of 193.45 g I/100 g oil and a peroxide index of 17.5 meq O2/kg oil. Chia oil showed a higher content of α and β linolenic and palmitic acids. Chia oil is the vegetable source with the highest content of essential fatty acids.

First Serological Evidence of Borna Disease Virus in Healthy Horses from Yucatan, Mexico

Borna Disease Virus (BDV) causes a progressive non-suppurative meningoencephalitis that sometimes occurs in mortality;this disease has been reported for over two centuries ago in horses, sheep and cats in Central Europe and some regions of Asia. Currently, it is known that it causes neurological symptoms in various species of vertebrates including human beings. In Yucatan, Mexico, there is a single serological report about the circulation of BDV in schizophrenia patients;however, nothing is known about the circulation in animals. We obtained serum samples of 100 horses without apparent clinical signs caused by BDV infection, from various sites in the region. Antibodies against BDV were detected by electrochemiluminescence immunoassay (ECLIA) method with three recombinant proteins: BDV p24, BDV p40 and BDV p10 as antigens;obtaining a high seroprevalence of 44% (44/100). This study generates the first report of the probable activity of the BDV in healthy horses in Mexico and has expanded the infiltration area of BDV in the world. Nevertheless, several molecular investigations are required to detect BDV-RNA circulating and find sequences for clarification of the origin of BDV in Mexican horses.

Intra-Domiciliary Transmission of Chagas’ Disease in Rural Areas of Yucatan Mexico

With the objective to describe the relationship between T. cruzi infection in humans and sinantropic reservoir and vectors in the rural conditions a study was performed in municipalities of the Yucatan state in Mexico. Blood samples from humans, dogs and opossum were taken from the households. Vectors were also collected and the infection and infestation indexes were calculated. Serum samples were evaluated by indirect hemagglutination (IH) and indirect immunofluorescence (IFI) to determine IgG antibodies against Trypanosoma cruzi. The polymerase chain reaction (PCR) was also performed in the samples taken from humans and reservoirs. Blood smears were performed in reservoirs. Sampled humans underwent to an electrocardiographic study to identify functional and conduction alterations of the heart. Household building characteristics were noted. A total of 367 blood samples were collected from people. The presence of IgG antibodies was 16.6% and 71.0% at PCR. Electrocardiographic studies revealed that 31% of patients seropositive to T. cruzi have a medical condition. 20.0% of dogs were seropositive and 68.5 positive to PCR. At the direct detection 13.6% resulted positive. In opossum 29.1% were seropositive and 72.9% positive to PCR. A total of 269 triatomineos were captured and 52.7% were infected with T. cruzi. The infection and infestation index were 52.4% and 60.8% respectively. The presence of adult vectors and their nymph’s were more frequently found in households made with wattle roofs (45.2 and 73.9 % respectively) than other kind of building materials. Electrocardiographic abnormalities found in positive persons were: Incomplete right bundle branch block (55%), tachycardia (35%), old myocardial infarction (5%) and incomplete block of the left bundle (5%). This work highlights the importance of comprehensive studies on the transmission of T. cruzi in the Yucatan where the link between human infection in synanthropic reservoirs and vectors is established. This information is important to design programs for the epidemiological surveillance and control to break the chain of transmission of the disease.

Unexpected Metastatic Recurrent Myxofibrosarcoma: A Scenario That May Be More Common than You Think

Soft tissue sarcomas represent only 1% of all adult cancers;myxofibrosarcoma is the most common type that arises in adult extremities, particularly lower limbs (77%), other less common locations are the trunk (12%) and neck (3%). Usually presenting as a painless, subcutaneous, slow growing mass with tendency for recurrence, they are prone to have higher histological grade and metastatic potential after recurrence;even in optimal multidisciplinary settings patients can have incomplete resections, making metastatic disease more common after misdiagnosis. We present the case of a 69-year-old male patient with a right infraescapular tumor, presenting as a painless 15 × 8 cm, mobile mass, with a slow but progressive growth, history of a previous tumor excised at the same location 5 years prior without histopathological report.

Heavy Metals Removal from Swine Wastewater Using Constructed Wetlands with Horizontal Sub-Surface Flow

The removal efficiency of Cu and Zn from swine wastewater was evaluated as effected by three variables: the hydraulic retention time (HRT) (24, 48, 72 and 96 hours), two different plant species (Typha domingensis Pers. and Eleocharis cellulosa) and two different sizes of filter media (5 and 15 mm) using a horizontal sub-surface flow constructed wetland. From the results, a significant difference was observed in the removal efficiency of Cu and Zn with respect to different hydraulic retention times. The best results were obtained in the HRT of 96 hours for Zn where 96% removal of Zn with Typha domingensis Pers. specie with gravel of 15 mm (experimental unit 6) was achieved. For Cu, at 72 hours of HRT, the efficiency was nearly 100% in five of the six study units (1, 2, 3, 5 and 6). In contrast, in experimental unit 4 with gravel of 15 mm and without plants, only 86% Cu removal was achieved.

Adsorption Kinetics of Matter Contained in a Leachate Using Eggshell and Activated Carbon

The generation of highly polluting leachate from Sanitary Landfills has prompted the development of technologies applicable to treatment of these liquids. The aim of this study was to determine the kinetics of adsorption of organic and inorganic matter contained in pre-treated leachate (by advanced oxidation by the Fenton reaction);after two adsorbents were used, first eggshell and then activated carbon. To determine the content of organic and inorganic matter COD was measured;this was the parameter for monitoring the kinetics. The leachate was subjected to advanced oxidation treatment by the Fenton reaction, then the adsorption process was conducted by batch, in two consecutive steps, the first step was the use of eggshell and the second step activated carbon. Due to the oxidation treatment the pH value decreased to 2, after the adsorption eggshell the pH increased to 6.9 and this was maintained in the treatment with activated carbon. The kinetics of adsorption of organic and inorganic matter on eggshell was evaluated by models pseudo-first-order and pseudo-second-order, the better fitting was the latter. The adsorption process was adjusted to the model of Langmuir. The negative value of △Hads indicated that the adsorption process was exothermic, spontaneous and favorable. The separation factor RL of Langmuir Isotherm values indicated that the adsorption of the matter on the eggshell was favorable at different temperatures. Finally, the activated carbon adsorption of liquid obtained from treatment with eggshell was favored with the kinetic model of pseudo second order. With the oxidation process, eggshell adsorption and activated carbon adsorption, the removal COD was 98.6%. The final COD value was fulfilled with the Mexican standard NOM-001-SEMARNAT-1996.

Obstructive Sleep Apnea Syndrome Implications on Health and Adherence to CPAP Treatment

Respiratory disorders during sleep have as a general characteristic the alteration of the respiratory cycle while sleeping. The most outstanding characteristic of Obstructive Sleep Apnea Syndrome (OSA) is the partial (hypopnea) or total (apnea) obstruction of the upper airway that occurs repeatedly during sleep. The OSA is global public health issue. When it is not treated, OSA represents a cost two or three times higher of the institutional resources for health. Studies conducted in different countries indicate that the prevalence of the OSA goes from 2% to 10% in general population. The OSA is a serious sleep disorder that has negative implications on multiple systems of the organism. It is associated with hypertension, diabetes and the metabolic syndrome. When OSA coexists with a heart disease or ischemic heart disease, it significantly raises the probability of a heart failure. The use of Continuous Positive Airway Pressure (CPAP) is so far the most effective method for OSA treatment. Intervention at different levels (physiological, educational and psychological intervention) appears to be important in adherence to CPAP treatment.

ACE-I inhibitory peptide fractions from enzymatic hydrolysates of velvet bean (<i>Mucuna pruriens</i>)

The hydrolysis of velvet bean (Mucuna pruriens) protein in the presence of Alcalase?-Flavourzyme? and Pepsin-Pancreatin was investigated. The results showed that Alcalase?-Flavourzyme? (29.08%) sequential system catalyzed the hydrolysis most efficiently that Pepsin-Pancreatin (24.78%). In addition, the higher ACE-I inhibitory activity was achieved with the sequential system Alcalase?-Flavourzyme? (33.13%). Furthermore, the concentration of peptides employing an ultrafiltration (UF) system or their purification by gel filtration chromatography showed that the oligomeric peptides with lower molecular weight registered the highest ACE-I inhibitory activity. It has been demonstrated that Mucuna pruriens protein hydrolysates could serve as a source of peptides with ACE inhibitory activity and this activity can be attributed mainly to the mixture of short peptides in the hydrolysate.

Bioactivity and Kinetic Study of <i>Jatropha curcas</i>Essential Oil Extraction Using Supercritical CO₂

This study reports the extraction of Jatropha curcas leaves using supercritical CO2. Experiments were performed varying the pressure (13 and 20 MPa) and the temperature (50°C and 60°C). The model of Sovová for supercritical fluid extraction was fitted to the experimental kinetic extraction curves. Two cell sizes were used and scale up equations compared. GC analysis showed phytol, carvacrol, and hexahydrofarnesyl acetone as major compounds in all the experiments. A maximum yield of 0.95% dry-weight basis was obtained. It was observed a maximum yield (0.95% dry-weight basis) extract obtained at 20 MPa and 50°C. The results indicated that the mass yield increased with the increase of pressure. The bioassays showed that the extract of J. curcas possessed toxicity against Hyalomma lusitanicum.

Lima Bean(Phaseolus lunatus)Protein Hydrolysates with ACE-I Inhibitory Activity

Several protein sources can be used to produce bioactive peptides with angiotensin I-converting enzyme (ACE) inhibittory activity. Protein concentrates from ungerminated and germinated lima bean Phaseolus lunatus seed flours were hydrolyzed with Alcalase 2.4 L or pepsin-pancreatin sequential hydrolysis, and ACE inhibitory activity measured in the different hydrolysis treatments. Protein hydrolysate production was analyzed with a 23 factorial design with four replicates of the central treatment. Evaluated factors were protein concentrate source (ungerminated seeds, PC1;germinated seeds, PC2), enzyme/substrate ratio E/S (1/50 or 1/10) and hydrolysis time (0.5 or 2.0 h for Alcalase;1 or 3 h for pepsin-pancreatin). Degree of hydrolysis (DH) was high for the Alcalase hydrolysates (24.12% 58.94%), but the pepsin-pancreatin hydrolysates exhibited the highest ACE inhibitory activity (IC50 = 0.250 0.692 mg/mL). Under the tested conditions, the hydrolysates with the highest ACE inhibitory activity were produced with sequential pepsin-pancreatin using either PC1 at 1 h hydrolysis time and a 1/10 E/S ratio or PC2 at 1 h hydrolysis time and a 1/50 E/S ratio. Lima bean protein hydrolysates prepared with Alcalase or pepsin-pancreatin are a potential ingredient in the production of physiologically functional foods with antihypertensive activity.

Rapid HPLC Method for Determination of Rebaudioside D in Leaves of Stevia rebaudiana Bertoni Grown in the Southeast of Mexico

Stevia leaves contain glycosides on which biological activity and sweetening capacity has been reported. Besides the main glycosides—stevioside and rebaudioside A—there are minor glycosides that may contribute to the activity and thus it is important to quantify them. Rebaudioside D is one of the minor glycoside present in S. rebaudiana leaves and there are no reports of a validated method to quantify it. Therefore a simple and sensitive high performance liquid chromatography (HPLC) method was validated for the determination of rebaudioside D in leaves of Stevia rebaudiana B. grown in the southeast of México. HPLC method was performed using a C18 column (250 mm × 4.6 mm, 5 μm) and UV detector set at 210 nm. The mobile phase consisted of 32:68 (v/v) mixture of acetonitrile and sodium phosphate buffer (10 mmol/L, pH 2.6), set to a flow rate of 1.0 ml/min. The calculated parameters were: sensitivity, linearity, limit of detection (LOD), limit of quantification (LOQ), accuracy and precision. The retention time of rebaudioside D was found to be 3.47 min ± 0.04 (S.D.). The calibration curves were linear over the working range (25 - 150 μg/ml), with correlation coefficient ≥0.99 and determination coefficient ≥0.98. The calculated limit of detection (LOD) was 8.53 μg/ml, while the limit of quantitation (LOQ) was 25.85 μg/ml. The percent recoveries of fortified samples were 100% ± 10% and precision relative standard deviation was ≤2.79%. The criteria of validation showed accuracy, linearity, and precision;therefore the method is suitable for quantitative analysis of rebaudioside D in Stevia rebaudiana leaves. Rebaudioside D content (g/100g) in Morita II and Criolla varieties grown in the southeast of Mexico were 0.43 and 0.46, respectively with no significant differences (p > 0.05) between them.

Chemical Composition and Antioxidant DPPH Activity of the Floral and Leaves Essential Oils of cMontanoa speciosa</i>DC

The essential oils obtained by hydrodistillation from leaves and flowers of Montanoa speciosa collected in southeastern Mexico (Yucatan) were analyzed by GC-MS. A total of 71 and 79 components, representing 98.44% and 97.69% of the leaf and flower oils, respectively, were characterized. The main constituents found were β-caryophyllene (20.73%, 17.95%), δ-cadinene (9.88%, 9.28%), caryophyllene oxide (9.48%, 8.68%), and germacrene D (6.94%, 5.85%). The essential oils were screened for their antioxidant potentials by DPPH assay. The leaves oil exhibited higher DPPH scavenging capability (72.85 ± 0.28 mmol TE/g essential oil and 147.83 ± 0.41 mg/mL Vit C/g essential oil) than the floral oil (68.43 ± 0.10 mmol TE/g essential oil and 131.59 ± 0.87 mg/mL Vit C/g essential oil).

Physicochemical and Functional Characterization of <i>Mucuna pruries</i>Depigmented Starch for Potential Industrial Applications

Starch is a very important biopolymer in the food industry. The velvet bean (M. pruriens) is an excellent potential starch source containing approximately 520 g starch per kg. The objective of this study was to evaluate the physicochemical and functional properties of velvet bean depigmented starch. The starch granules appear oval and spherical shaped. The colour registered L*, a*, b* values of 44.9, 0.324 and 0.341 respectively. The chemical composition registered values of moisture, ash, fat, protein, fibre and NFE of 110.5, 5.8, 5.7, 0.0, 34 and 954.5 g/kg respectively, as well as amylose levels of 215.3 g/kg. Gelatinization onset (To), peak (Tp) and final (Tf) temperatures were of 74.23°C, 80.57°C and 86.39°C. The solubility (3.1% - 16.2%), swelling power (SP) (2.86% - 16.17%) and water absorption capacity (WAC) (2.67 - 15.95 g water/g starch) were directly correlated to temperature (60°C - 90°C). The enthalpy values (4.10 - 13.47 j/g) were directly correlated to the time (1 - 21 days). The retrogradation increased as time increased. The viscosity of M. pruriens depigmented starch decreased slightly during the heating stages and then increased during cooling and the refrigeration and freezing stability registered syneresis ranges from 17.65 to 23.18 mL/50mL and from 16.4 to 22.6 mL/50mL respectively, indicating that the depigmented starch was unstable in heating-cooling processes.

The<i>I</i>550<i>V</i>polymorphism in the renal human sodium/dicarboxylate cotransporter 1 (<i>hNaDC</i>-1) gene is associated with the risk for urolithiasis in adults from Southeastern, Mexico

Urolithiasis (UL) is an endemic disease in Southeastern, Mexico. In order to evaluate the association of I550V polymorphism in the hNaDC-1 gene with risk for hypocitraturia and/or for UL;139 adults with UL and 132 adults without UL, were included under a case-control association study. Citrate levels in 24-h urine were quantified (citraturia). The polymorphism I550V-hNaDC-1 was determined by PCR-RFLP. Statistical analysis was performed using the STATA10.2 software. Comparison of genotype and allele frequencies between subjects with and without UL showed significant differences for genotype bb (OR = 2.34, CI: 1.19-4.59, p = 0.01) and for allele b (OR = 1.62, CI: 1.15-2.28, p = 0.005), suggesting an association with the risk for UL. Comparison of genotype and allele frequencies between subjects with hypocitraturia and subjects with normocitraturia, did not show any significant difference (p > 0.05), suggesting that this polymorphism is not associated with the risk of hypocitraturia. Interestingly, the risk for UL was increased due to an additive effect of hypocitraturia with the genotype bb (OR = 6.6, CI: 2.38-18.28, p = 0.0002) or with the allele b (OR: 4.2, CI = 2.52-6.97,

Nitric oxide production is associated to increased lipoperoxidation and active caspase-3 in demyelinated brain regions of the taiep rat

We previously showed that the increase in nitric oxide (NO) levels and NO synthase (NOS) expression correlate with the progression of reactive astrocytosis and demyelination in the brains of 6-month-old taiep rats. Increased levels of NO can result in high concentration of peroxynitrite and thus cause tissue damage, which consists of lipoperoxidation of the cytoplasmic membrane, such as the myelin, and of apoptotic and necrotic cell-death. On this basis, we studied whether the increased NO production is associated with lipoperoxidation and cell death in the cerebellum and brainstem over the age (1, 3, 6, and 8 months) of taiep rats. The results were compared with those obtained in matched Sprague-Dawley (SD) rats. We measured the levels of nitrites (NO production), malonyldialdehyde, and 4-hydroxyalkenal (lipoperoxidation) in brain tissue homogenates. The three NOS isoforms and cleaved caspase-3 were evaluated by using ELISA and immunostaining techniques. Our results showed that NO production and lipoperoxidation increased in the cerebellum and brainstem as the age of the taiep rats increased compared to SD rats. The overexpression of nNOS and iNOS were in the Purkinje cells, magnocellular neurons, and in oligodendrocytes, whereas the glial cells showed strong cleaved-caspase-3 immunoreactivity. In summary our results suggest that NO plays a role in the demyelination and cell death in the taiep rat.

Mexican Guidelines for the Diagnosis and Treatment of Chronic Myeloid Leukaemia

Background: This document includes recommendations and guidelines issued by a group of Mexican researchers and specialists gathered in the First National Colloquium for the Diagnosis and Management of Chronic Myeloid Leukaemia (CML) by initiative of Instituto Nacional de Cancerología and with the support of the Leukaemia Department of the MD Anderson Cancer Center. Mexico lacks of updated information taken from its own reality on the diagnosis and treatment of CML and other haematological disorders;besides, there are no national guidelines. Aim: To publish a consensus document with guidelines for the management of CML adjusted to the national environment and overall characteristics. Method: The participants answered a DELPHI questionnaire about the overall aspects of the disease, aiming to target controversial topics, discuss them in the colloquium, and to agree on the best ones. After those meetings, a final document was drawn up. Results: The group presents recommendations for definition, diagnosis, prognosis, monitoring, and treatment of CML in Mexico. Conclusions: Having consensus guidelines for the clinical management of CML in our country will enable the consensual practice of Mexican specialists regarding the clinical approach to CML, as well as optimize the resources which allow the rational planning of the medical care strategies.

Comparison of Chemical and Functional Properties of Stevia rebaudiana(Bertoni)Varieties Cultivated in Mexican Southeast

The leaf powders from two varieties of Stevia rebaudiana (Bertoni) cultivated in Yucatan, Mexico were analyzed for their proximate composition, dietary fiber composition and functional properties. The leaf powders were a good source of carbohydrates (64.06%-67.98%), protein (12.11%-15.05%), and crudefiber (5.92%-9.52%). Total dietary fiber content in the S. rebaudiana leaf powders were 28.61 (Morita II) and 29.12 (Criolla) g/100g sample, with most of this content represented by insoluble dietary fiber 87.79% (Morita II) and 70.02% (Criolla). Neutral detergent fiber (NDF), acid detergent fiber (ADF) and acid detergent lignin (ADL) were higher in Criolla (19.29%, 17.77%, 8.98%) than Morita II variety (18.11%, 14.16%, 2.28%). Hemicellulose and cellulose were higher in Morita II (3.96%, 11.78%) than criolla variety (1.51%, 8.79%). Functional properties of leaf powder from Morita II and Criolla were, water-holding capacity (2.87-4.07 g/g sample), oil-holding capacity (6.49-6.79 g/g sample), water-absorption capacity (3.41-3.44 g/g sample), water-adsorption capacity (0.25-0.28 g/g sample), and organic molecule absorption capacity (1.13-1.81 g/g sample). These suggest that S. rebaudiana (Bertoni) leaf powders may be used as dietary supplement or as food additive.

Survival and growth of dominant tree seedlings in seasonally tropical dry forests of Yucatan: site and fertilization effects

Aims Seasonally tropical dry forests of the Yucatan Peninsula are typically found in sites with nutrient-poor soils because of the recent geologi-cal origin of the region.The landscape is dominated by extensive karstic plates that shape environments where vegetation regenera-tion through seed germination may be limited by the availability of suitable microsites.In this study,we documented the survival and growth of seedlings from three dominant tree species(Bursera simaruba,Piscidia piscipula and Lysiloma latisiliquum)in seasonally tropical dry forests in Yucatan.Specifically,we evaluated the effect of nutrient addition(N and P,separately and in combination)on seedling survival and growth across three sites with differing levels of precipitation.Methods We conducted a nutrient addition experiment,whereby we estab-lished 12 plots of dimensions 10×10 m(100 m^(2))at each site,from which three plots were randomly selected to receive one of four treatments:N addition,P addition,N and P addition and no nutri-ent addition(controls).Prior to treatment application,in each plot,we planted 10 seedlings of each species in October 2010 and sub-sequently conducted surveys of plant growth and survival every 20 days from November 2010 to April 2011.Important Findings Overall,nutrient addition increased seedling survival and the mag-nitude of this effect was similar among sites.We did not observe an additive effect of the N+P treatment on survival.Similarly,we observed a positive effect of nutrient addition on seedling growth,but this effect was contingent upon site;regarding survival,the effects of N and P on seedling growth were not additive.These results suggest that seedling recruitment and growth in the three dominant species of trees in Yucatan are limited by nutrient avail-ability but that the magnitude of this effect,particularly on seedling growth,is specific for species and site.