Showing papers by "University of Córdoba (Spain) published in 1996"

Molecular biology of prostatic intraepithelial neoplasia.

Abstract: High-grade PIN is the most likely precursor of prostatic adenocarcinoma, according to virtually all available evidence to date. The clinical importance of recognizing PIN is based on its strong association with prostatic carcinoma. PIN has a high predictive value as a marker for adenocarcinoma. Its identification in biopsy specimens of the prostate warrants further search for concurrent invasive carcinoma. PIN is associated with progressive abnormalities of phenotype and genotype intermediate between normal prostatic epithelium and cancer, indicating impairment of cell differentiation and regulatory control with advancing stages of prostatic carcinogenesis. There is progressive gain or loss of a wide variety of biomarkers, including morphometric markers, differentiation markers, stromal markers, growth factors and associated receptors, oncogenes, tumor suppressor genes, and chromosomes. Abnormalities in expression of most biomarkers are amplified in the progression from high-grade PIN to localized cancer, metastatic cancer, and hormone-refractory cancer. Oncogenesis of prostatic carcinoma probably occurs through the selection of several genetic changes, each modifying the expression or function of genes controlling cell growth and differentiation. Further studies are needed to evaluate the function and prognostic value of oncogene expression in the normal, preneoplastic, and neoplastic prostate.

Long-Term Tillage, Crop Rotation, and Nitrogen Fertilizer Effects on Wheat Yield under Rainfed Mediterranean Conditions

Abstract: The combined long-term effects of tillage method and crop rotation on crop yield have not been studied in rainfed systems under Mediterranean climates. A field study was conducted from 1988 to 1994 to determine the effects of tillage (TILL), crop rotation (ROT) and N fertilizer on wheat (triticum aestivum L.) yield in a rainfed Mediterranean region. Tillage treatments include no tillage (NT) and conventional tillage (CT). Crop rotations were wheat-sunflower (Helianthus annuus L.) (WS), wheat-chickpea (Cicer arietinum L.) (WCP), wheat-fababean (Vicia faba L.) (WFB), wheat-fallow (WF), and continuous wheat (CW), with N fertilizer rates of 50, 100, and 150 kg N ha -1 . A split-split plot design with four replications was used. Differences in rainfall during the growing season had a marked effect on wheat yield. Amount of rainfall during the vegetative period for wheat (November-February) was highly correlated with yield because of the high water-retention capacity of Vertisols (Typic Haploxerert). In dry years, wheat yield was greater under NT than under CT ; the opposite was true in wet years. The TILL x ROT interaction was also significant in the drought years ; the wheat yield under NT was greater for CW and the WFB and WF rotations than under CT. Wheat yields ranked by crop rotation were : WFB > WF >> WCP > WS >> CW. Wheat did not respond to N fertilizer when rainfall was below 450 mm during the growing season. Using these results strategies can be developed for establishing the N fertilizer rate applied to wheat as a function of rainfall, the preceding crop, and residual N in soil in order to optimize wheat yield and reduce nitrate pollution to groundwater.

Role of Apoplastic and Cell-Wall Peroxidases on the Stimulation of Root Elongation by Ascorbate.

Abstract: Elongation of onion (Allium cepa L.) roots was highly stimulated by ascorbate (ASC) and its natural precursor I-galactone-[gamma]-lactone (GL). When incubation media were supplemented with lycorine (Lyc), an inhibitor of the ASC biosynthesis, root growth was negligible even in the presence of ASC or GL. ASC completely inhibited in vitro guaiacol peroxidase activities that were isolated from both the apoplast and the cell wall. However, ferulic-acid-dependent peroxidase from the cell wall was partially inhibited by ASC, whereas ferulic acid peroxidase activity from the apoplastic fluid was completely inhibited by ASC as long as ASC was present in the assay medium. ASC content in cells was increased by preincubations with ASC or GL, whereas Lyc reduced it. On the other hand, ASC or GL treatments decreased both apoplast and cell-wall-bound peroxidase activities, whereas Lyc had a slight stimulating effect. These results are discussed on the basis of a possible control of root elongation by ASC via its action on peroxidases that are involved in the regulation of cell-wall extensibility.

Report on the progress of standardization of the G-Banded canine (canis familiaris) karyotype

Abstract: Karyotyping of dog chromosomes is a difficult task owing to the high diploid number of chromosomes (2n=78) and the similar morphology of autosomes, all of which are acrocentrics. In this report 22 of the 39 G-banded chromosome pairs and their corresponding ideograms have been standardized. The ideogram comprises altogether 235 bands. The need for the introduction of molecular techniques such as chromosome painting and physical mapping of genetic markers for the identification of small acrocentrics is discussed.

Immunohistochemical Characterization of Canine Transmissible Venereal Tumor

Abstract: The collective immunohistochemical expression of human lysozyme, human alpha-1-antitrypsin, human CD3 antigen, calf vimentin, human keratins, human lambda light chains,canine immunoglobulins IgG, IgM, and bovine protein S-100 has been analyzed on formalin-fixed, paraffin-embedded tissue sections of 25 spontaneous canine transmissible venereal tumors (CTVT) from both genital and extragenital locations using the avidin-biotin-peroxidase complex technique. Lysozyme immunoreactivity was detected in 10/25 CTVT, alpha-1-antitrypsin in 14/25 CTVT, and vimentin in 25/25 CTVT. All CTVT cells were negative to keratins 5 + 8 of the Moll catalogue (RCK-102), S-100 protein, lambda light-chain immunoglobulins, IgG, IgM, and CD3 antigen. The intratumoral T-and B-lymphocyte infiltrate was differentiated using CD3 antigen, lambda light-chain immunoglobulins, IgG, and IgM, and this technique could be useful to evaluate the regressive or progressive growth stage of venereal tumors. Our findings support the hypothesis of a histiocytic immunophenotype for CTVT, and these staining techniques could be used in the differential diagnosis with lymphomas.

Isolation of periplasmic nitrate reductase genes from Rhodobacter sphaeroides DSM 158: structural and functional differences among prokaryotic nitrate reductases.

Abstract: Summary The prototrophic bacterium Rhodobacter sphaeroides DSM 158 has a periplasmic nitrate reductase which is induced by nitrate and it is not repressed by ammonium or oxygen. In a Tn5 mutant lacking nitrate reductase activity, transposon insertion is localized in a 1.2 kb EcoRI fragment. A 0.6 kb BamHI-EcoRI segment of this region was used as a probe to isolate, from the wild-type strain, a 6.8 kb Pstl fragment carrying the putative genes coding for the periplasmic nitrate reductase. In vivo protein expression and DNA sequence analysis reveal the presence in this region of three genes, napABC, probably organized in an operon. These genes are required for nitrate reduction, as deduced by mutational and complementation studies. The napA gene codes for a protein with a high homology to the periplasmic nitrate reductase from Alcali-genes eutrophus and, to a lesser extent, to other prokaryotic nitrate reductases and molybdenum-containing enzymes. The napB gene product has two haem c-binding sites and shows a high homology with the cytochrome c-type subunit of the periplasmic nitrate reductase from A. eutrophus. NAPA and NAPB proteins appear to be translated with signal peptides of 29 and 24 residues, respectively, indicating that mature proteins are located in the periplasm. The napC gene codes for a 25 kDa protein with a transmembrane sequence of 17 hydrophobic residues. NAPC has four haem c-binding sites and is homologous to the membrane-bound c-type cytochromes encoded by Pseudomonas stutzeri nirT and Escherichia coli torC genes. The phenotypes of defined insertion mutants constructed for each gene also indicate that periplasmic nitrate reductase from R. sphaeroides DSM 158 is a dimeric complex of a 90kDa catalytic subunit (NAPA) and a 15kDa cytochrome c (NAPB), which receives electrons from a membrane-anchored tetrahaem protein (NAPC), thus allowing electron flow between membrane and periplasm. This nitrate-reducing system differs from the assimilatory and respiratory bacterial nitrate reductases at the level of cellular localization, regulatory properties, biochemical characteristics and gene organization.

Myosin heavy chain isoforms in adult equine skeletal muscle : an immunohistochemical and electrophoretic study

Abstract: Background The aim of this study was to characterize the myosin heavy chain (MyHC) isoforms present in equine skeletal muscle. Methods Muscle biopsies were removed from the superficial region of the gluteus medius muscle of five mature horses and analyzed by immunohistochemistry (using a battery of monoclonal antibodies specific for rat MyHC isoforms) and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Results Immunohistochemistry allowed subdivision of three different muscle fiber populations containing a single MyHC, one slow and two fast, and two hybrid populations, one containing slow and fast MyHCs and another with both fast-MyHC isoforms. Electrophoresis of MyHC confirmed the existence of three resolvable bands, with an electrophoretic mobility parallel to type I, IIa, and IIx rat MyHCs. The identities of two of these MyHCs were easily comparable with slow type I and fast type IIa MyHCs from rat skeletal muscle. However, a precise identification of the second fast MyHC was not made. Conclusions These results show the presence of three different MyHC isoforms in mature equine skeletal muscle, whose differential distribution defines three fiber types containing a single MyHC and two hybrid fiber populations containing either both slow and fast type IIa MyHCs or both fast MyHC isoforms. © 1996 Wiley-Liss, Inc.

European soils overfertilized with phosphorus: Part 1. Basic properties

Abstract: Soils overfertilized with phosphorus (P) are widespread in the European Union and there is consensus among soil scientists to better explore their potential to release phosphate. In this work we report the principal physical and chemical properties of twelve overfertilized benchmark soils of contrasting agricultural areas in Italy, Germany, Great Britain, and Spain. The criterion used to consider them as overfertilized was that the available P amount, measured by the regional soil P test, was at least twice as large as the accepted critical level for an average crop. The soils could be usefully divided into three groups, calcareous, slightly acidic and acidic based upon their basic chemical properties and reactions and proportion of the major P fractions (NaOH- plus citrate-bicarbonate-, citrate-bicarbonate-dithionite-, and HCl-extractable P). Six extraction procedures commonly used to evaluate potentially plant-available P (Olsen, anion-exchange resin (resin-), anion plus cation-exchange resin (resin±), Ca acetatelactate (CAL), water, and Fe oxide-impregnated paper strips (strip) were compared. The extractable P values by each method were correlated but the amount of P extracted varied and differed in the order water-P< Olsen-P< CAL-P< strip-P< resin(±)-P

Airborne ascospores of Didymella rabiei as a major primary inoculum for Ascochyta blight epidemics in chickpea crops in southern Spain

Abstract: The incidence and severity of Ascochyta blight in potted chickpea trap plants exposed for 1-wk periods near infested chickpea debris in Cordoba, Spain, or in chickpea trap crops at least 100 m from infested chickpea debris in several locations in southern Spain were correlated with pseudothecial maturity and ascospore production ofDidymella rabiei from nearby chickpea debris. The period of ascospore availability varied from January to May and depended on rain and maturity of pseudothecia. The airborne concentration of ascospores ofD. rabiei was also monitored in 1988. Ascospores were trapped mostly from the beginning of January to late February; this period coincided with that of maturity of pseudothecia on the chickpea debris. Most ascospores were trapped on rainy days during daylight and 70% were trapped between 12.00 and 18.00 h. Autumn-winter sowings of chickpea were exposed longer to ascospore inoculum than the more traditional spring sowings because the autumn-winter sowings were exposed to the entire period of ascospore production on infested chickpea debris lying on the soil surface.

Occurrence of metals in waters : an overview

Abstract: Presence of metals in natural, drinking and waste waters can imply two types of circumstances (depending on concentration and specific metal) : firstly, certain positive effects, especially, when the metals present in drinking water are essential for human life (e.g. Mo and Zn) ; secondly, some negative and toxicologically undesirable effects for both human consumption and the general environment (i.e. Cd, Hg). This paper gives an overview of outstanding aspects related to the chemical behaviour, occurrence, physiology and toxicology of the 25 metals most frequently found in waters : Aluminium, antimony, arsenic, barium, beryllium, boron, cadmium, calcium, chromium, cobalt, copper, iron, lead, lithium, magnesium, manganese, mercury, molybdenum, nickel, potassium, sodium, selenium, silver, tin and zinc. On the other hand, the maximum concentrations of metals in natural, drinking waters and waste waters are listed according to the actual Spanish regulations. Finally, references to the maximum levels of metals in drinking waters established by a recent proposal of Directive in the European Union, as well as the latest WHO's guideline values for metals have been also considered.

Partial stacking of a water-soluble porphyrin in complex monolayers with insoluble lipid

Abstract: Mixed monolayers of a water-soluble tetracationic porphyrin (TMPyP) and an insoluble lipid matrix with anionic head groups (DMPA) were formed by the cospreading method. A ratio TMPyP:DMPA = 1:4 was selected by investigation of π−area isotherms and stability of the cospread monolayer. Reflection spectroscopy has been used to infer the molecular organization of the porphyrin molecules in the complex monolayer at the air−water interface. A blue shift in the Soret band was observed with increasing surface pressure. The mixed monolayer of TMPyP:DMPA = 1:4 was transferred onto a glass substrate, and the molecular organization of the porphyrin was studied by transmission spectroscopy with plane polarized light (s and p) under various angles of incidence. The analysis of the reflection spectra at the air−water interface and absorption spectrum of the mixed monolayer on glass leads to a model of partial stacking of the porphyrin molecules in the monolayer at the air−water interface when the surface pressure is inc...

Correlation between myofibrillar ATPase activity and myosin heavy chain composition in equine skeletal muscle and the influence of training

Abstract: Background The histochemical myofibrillar ATPase (mATPase) method is used routinely for identification of equine skeletal muscle fiber types, but important problems have been observed with the subdivision of fast fiber population when using this method. To verify the use of this qualitative method, a number of equine muscle biopsies were analyzed with a combination of histochemical, immunohistochemical, electrophoretic, and morphometric techniques. The influence of training on these interrelations was also evaluated. Methods Five young (2–3 years old) thoroughbred horses were intensively trained for 8 months on a high-speed treadmill. Biopsies were taken from the gluteus medius muscle at the beginning, after 4 months, and at the end of the training program. Serial sections of the samples were stained by mATPase histochemistry and immunohistochemistry by using a number of monoclonal antibodies specific to selected myosin heavy chain (MyHC) isoforms. The histochemical and immunohistochemical categorization of a large number of fibers (N = 2,078) was compared fiber by fiber. The MyHC content of homogenates of the same biopsies were quantified by densitometry of a sensitive gel electrophoretic technique and compared with histochemical and immunohistochemical fiber types. Results A large proportion of fibers examined (∼20%) were misclassified by traditional mATPase histochemistry. Many fibers histochemically identified as type IIB displayed both type IIa and type IIb MyHC isoforms, and nearly all type IIAB fibers in mATPase contained only the type IIa MyHC isoform by immunohistochemistry. Correlation analyses suggested a weak relation between the histochemically assessed relative cross-sectional area occupied by the three major fiber types (I, IIA, and IIB) and the electrophoretically assessed MyHC content, whereas a stronger relation was found between immunohistochemically defined fiber types and electrophoretic data. The four fiber type populations delineated according to MyHC content (I, IIA, IIAB, and IIB) had sizes and oxidative capacities significantly different from each other. No adaptation of any parameter measured to training was found. Training had no significant effect on the number of fibers misclassified by mATPase histochemistry. Conclusions These data demonstrate a significant limitation in mATPase histochemistry for assessing fibers containing fast MyHC isoforms. The use of monoclonal antibodies against specific MyHC isoforms seems to be a more sensitive and less subjective method. © 1996 Wiley-Liss, Inc.

Immunohistochemical Characterization of Hemangiopericytomas and Other Spindle Cell Tumors in the Dog

Abstract: The immunohistochemical expression of muscle actin has been studied in 45 canine hemangioperi- cytomas (CHP) using a monoclonal antibody (HHF35) and formalin-fixed, paraffin-embedded specimens. The distribution of vimentin, desmin, cytokeratins, lysozyme, factor VIII-related antigen, S- 100 protein, and glial fibrillary acidic protein was studied both in CHP and in some canine soft-tissue neoplasms (seven fibrosarcomas, seven benign schwannomas, seven benign fibrous histiocytomas, and six leiomyosarcomas) used as controls for differential diagnosis. All CHP and control tumors expressed vimentin. Twenty-three CHP expressed muscle actin, whereas all control tumors analyzed were muscle actin-negative, with the exception of leiomyosarcomas. Among muscle actin- and vimentin-positive CHP, one case could be reclassified as leiomyosarcoma because it was desmin-positive, two cases expressed lysozyme, and nine cases expressed S- 100 protein. Among muscle actin-negative and vimentin-positive CHP, seven expressed S- 100 protein. In addition, S- 100 protein was detected in five schwannomas. All CHP and control tumors analyzed were negative for cytokeratins, factor VIII-related antigen, and glial fibrillary acidic protein. Our results support the hypothesis of a pericytic origin of CHP, and suggest that muscle actin, desmin, vimentin, and lysozyme could be useful for the differential diagnosis of canine spindle cell tumors, but not all these neoplasms can be identified with these tumor tissue markers. Both human and canine hemangiopericytomas (CHP) are rather uncommon cutaneous neoplasms of adult life and are more often found in the legs and hindlimbs, respectively. Human HP has also been found in non- cutaneous locations, whereas CHP has been exclu- sively described in the ~kin.~~s~~ In man, the metastatic rate varies from 1 1.7% to 56.5%, and recurrence is more ~ommon,~ whereas in the dog the recurrence rate varies from 26% to 60%, and when it occurs the tumor becomes more agressive. However, metastasis of CHP

Myosin isoforms and muscle fiber characteristics in equine gluteus medius muscle.

Abstract: Background To date, four different myosin heavy chain (MyHC) isoforms have been identified in adult skeletal muscle of a number of species: types I, IIa, IIx or IId, and IIb. The aim of this study was to investigate the distribution of various MyHC isoforms in the equine gluteus medius and gluteus profundus muscles in relation with several morphometric variables of muscle fibers. Methods Samples from different depths of the gluteus medius muscle (2, 4, 6, and 8 cm) and gluteus profundus muscle of five sedentary horses were examined by MyHC gel electrophoresis, monoclonal antibodies staining against fast, slow and neonatal MyHC isoforms, myosin adenosine triphosphatase (m-ATPase) activity, nicotinamide adenine dinucleotide tetrazolium reductase, α-glycerophosphate dehydrogenase, and α-amylase-PAS. Data about relative frequencies, sizes, and capillaries of the various histochemical fiber types were collected by morphometry. Results Three MyHC isoforms were present in the gluteus medius muscle. Two of them comigrated with type I and IIa MyHC isoforms of rat diaphragm (used as a control). The third isoform showed an electrophoretic mobility closer to type IIx than to the IIb MyHC isoform of rat diaphragm. Only two MyHC isoforms (type I and IIa) were detected in the gluteus profundus muscle. In both muscles, type I fibers (high m-ATPase activity at pH 4.5) only reacted with the anti slow-MyHC antibody and both type IIA and IIB fibers (low and moderate m-ATPase activity at pH 4.5, respectively) only reacted with the anti fast-MyHC antibody. No cross-reactivity of fibers positive for both antibodies was found except for the scarce type IIC fibers. Fiber types and capillaries were heterogeneously distributed across the gluteus medius muscle. The deeper regions of this muscle were found to contain a higher percentage of type I fibers, a large number of capillaries and a lower proportion of type IIB fibers compared to the superficial regions of the muscle. The gluteus profundus muscle had more abundant and larger type I fibers than the deepest sampling site of the gluteus medius muscle. Conclusions These results show the existence of three different MyHC isoforms in the equine gluteus medius muscle and that fiber types and MyHC isoforms are heterogeneously distributed within this muscle. The distribution of slow-twitch and fast-twitch MyHCs among the fibers determined by immunohistochemistry was in agreement with histochemically identified type I and type II fibers, respectively. © 1996 Wiley-Liss, Inc.

Strategies for supercritical fluid extraction of polar and ionic compounds

Abstract: The methods used to facilitate the supercritical fluid extraction (SFE) of polar and ionic compounds are based on two general principles, either increasing the polarity of the supercritical fluid (SF) (usually C02) used as extractantor reducing the polarity of the analytes to be leached from the solid matrices. Changes in the pressure and temperature of the SF, the use of SFs more polar than CO2 or of modified CO2, ion pair formation, esterification, the use of and organometalIics, or complex formation are the most common ways of increasing the extraction efficiency for polar and ionic analytes.

Modified plant plasma membrane H+‐ATPase with improved transport coupling efficiency identified by mutant selection in yeast

Abstract: Transport across the plasma membrane is driven by an electrochemical gradient of H+ ions generated by the plasma membrane proton pump (H(+)-ATPase). Random mutants of Arabidopsis H(+)-ATPase AHA1 were isolated by phenotypic selection of growth of transformed yeast cells in the absence of endogenous yeast H(+)-ATPase (PMA1). A Trp-874-Leu substitution as well as a Trp-874 to Lys-935 deletion in the hydrophilic C-terminal domain of AHA1 conferred growth of yeast cells devoid of PMA1. A Trp-874-Phe substitution in AHA1 was produced gy site-directed mutagenesis. The modified enzymes hydrolyzed ATP at 200-500% of wild-type level, had a sixfold increase in affinity for ATP (from 1.2 to 0.2 mM; pH 7.0), and had the acidic pH optimum shifted towards neutral pH. AHA1 did not contribute significantly to H+ extrusion by transformed yeast cells. The different specifies of aha1, however, displayed marked differences in initial rates of net H+ extrusion and in their ability to sustain an electrochemical H+ gradient. These results provide evidence that Trp-874 plays an important role in auto-inhibition of the plant H(+)-ATPase and may be involved in controlling the degree of coupling between ATP hydrolysis and H+ pumping. Finally, these results demonstrate the usefulness of yeast as a generalized screening tool for isolating regulatory mutants of plant transporters.

Purification and characterization of tomatinase from Fusarium oxysporum f. sp. lycopersici

Abstract: The antifungal compound alpha-tomatine, present in tomato plants, has been reported to provide a preformed chemical barrier against phytopathogenic fungi. Fusarium oxysporum f. sp. lycopersici, a tomato pathogen, produces an extracellular enzyme inducible by alpha-tomatine. This enzyme, known as tomatinase, catalyzes the hydrolysis of alpha-tomatine into its nonfungitoxic forms, tomatidine and beta-lycotetraose. The maximal tomatinase activity in the fungal culture medium was observed after 48 h of incubation of germinated conidia at an alpha-tomatine concentration of 20 micrograms/ml. The enzymatic activity in the supernatant was concentrated against polyethylene glycol 35,000, and the enzyme was then purified to electrophoretic homogeneity by a procedure that includes preparative isoelectric focusing and preparative gel electrophoresis as main steps. The purification procedure had a yield of 18%, and the protein was purified about 40-fold. Tomatinase was found to be a monomer of 50 kDa by both native gel electrophoresis and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The analytical isoelectric focusing of the native tomatinase showed at least five isoforms with pIs ranging from 4.8 to 5.8. Treatment with N-glycosidase F gave a single protein band of 45 kDa, indicating that the 50-kDa protein was N glycosylated. Tomatinase activity was optimum at 45 to 50 degrees C and at pH 5.5 to 7. The enzyme was stable at acidic pH and temperatures below 50 degrees C. The enzyme had no apparent requirement for cofactors, although Co2+ and Mn2+ produced a slight stimulating effect on tomatinase activity. Kinetic experiments at 30 degrees C gave a K(m) of 1.1 mM for alpha-tomatine and a Vmax of 118 mumol/min/mg. An activation energy of 88 kJ/mol was calculated.

Threonine 80 on HLA-B27 confers protection against lysis by a group of natural killer clones

Abstract: Recognition of major histocompatibility complex (MHC) class I molecules on target cells by natural killer (NK) cells inhibits NK cell-mediated lysis. Although it is known that this inhibitory effect is regulated by MHC polymorphism, the precise structural determinants remain undefined. Based on the capacity of different HLA-C and HLA-B motifs specifically to inhibit cytotoxicity of some NK clones, three different NK cell specificities (NK1, NK2 and NK3) have been described. In this study, the recognition of HLA-B27 by NK clones has been analyzed using C1R cells transfected with different HLA-B27 subtypes as target cells. Cytotoxicity was inhibited by the HLA-B*2705, -B*2701 -B*2703, -B*2704 and -B*2706 alleles, but not by -B*2702. This subtype is distinguished from the other B27 subtypes by the presence of isoleucine instead of threonine at position 80. Direct involvement of this residue was assessed by showing that site-directed mutagenesis of Thr80 to Ile80 in HLA-B*2705 reverted the NK protective effect of HLA-B*2705. Based on these data, we suggest that Thr80 could act as a single residue conferring target cell protection from lysis by a group of NK clones, tentatively designated NK4.

Polymeric SUC genes in natural populations of Saccharomyces cerevisiae

Abstract: The comparative chromosomal locations of polymeric β-fructosidase SUC genes have been determined by Southern blot hybridization with the SUC2 probe in 91 different strains of Saccharomyces cerevisiae. Most of the strains exhibited a single SUC2 gene, but in some strains two or three SUC genes were found. All Suc− strains carried a silent suc20 sequence. The accumulation of SUC genes was observed in populations derived from sources containing sucrose and seems to be absent in strains from sources promoting the MEL gene.