Chitosan inhibits growth of spoilage micro-organisms in chilled pork products

The aim of this study was to develop novel preservation systems for chilled, comminuted pork products that are sold raw using the natural compound chitosan (polymeric ß -1,4- N -acetylglucosamine). In vitro testing showed that viable numbers of Saccharomycodes ludwigii were reduced by up to 4 log cfu ml⁻¹ on exposure to 0·05% chitosan in 0·9% saline at pH 6·2. Higher concentrations of chitosan (0·25 and 0·5%) were required to achieve similar levels of inactivation withLactobacillus viridescens, Lac. sake and Listeria innocua. Torulaspora delbrueckii and Salmonella enteritidis PT4 were resistant to chitosan at the concentrations tested in this study (up to 0·5%). Trials in real foods showed that dipping of standard and skinless pork sausages in chitosan solutions (1·0%) reduced the native microflora (total viable counts, yeasts and moulds, and lactic acid bacteria) by approximately 1–3 log cfu g⁻¹ for 18 days at 7°C. Chitosan treatment increased the shelf-life of chilled skinless sausages from 7 to 15 days. Addition of 0·3 and 0·6% chitosan to an unseasoned minced pork mixture reduced total viable counts, yeasts and moulds, and lactic acid bacteria by up to 3 log cfu g⁻¹ for 18 days at 4°C compared with the untreated control. The results indicated that chitosan was an effective inhibitor of microbial growth in chilled comminuted pork products.     

Response of pancreatic secretions to feeding diets with low and high levels of soybean trypsin inhibitors in growing pigs

Studies were carried out to determine the effect of soybean trypsin inhibitors (SBTI) on exocrine pancreatic secretions in growing pigs. Six barrows with an average initial body weight (BW) of 27·1±1·4 kg were fitted with permanent pancreatic re-entrant cannulas and fed two diets according to a crossover design. Two maize starch-based diets were formulated to contain 200 g kg⁻¹ crude protein from either Nutrisoy (food grade defatted soy flour) or autoclaved Nutrisoy. The concentrations of SBTI in Nutrisoy and autoclaved Nutrisoy diets were 13·4 and 3·0 g kg⁻¹, respectively. The experiment consisted of two periods of 9 days each. The average BW at the start of the first and second experimental periods was 33·5±2·7 and 37·2±3·7 kg, respectively. The average BW at the conclusion of the experiment was 41·8±3·9 kg. The volume of pancreatic secretion was higher (P<0·01) when the Nutrisoy, as opposed to the autoclaved Nutrisoy diet was fed (3804 vs 2634 ml (24 h)⁻¹). The concen-tration of nitrogen and protein and specific activities (units litre⁻¹) of amylase, chymotrypsin and trypsin were lower (P<0·05) in pancreatic juice of pigs fed the Nutrisoy diet. There were no differences (P>0·05) in the total secretions of nitrogen (g (24 h)⁻¹) and total activities (units (24 h)⁻¹) of amylase, lipase, chymotrypsin and trypsin in pancreatic juice of pigs fed the Nutrisoy and autoclaved Nutrisoy diets. However, the total secretion of protein was slightly higher (25·7 vs 22·8 g (24 h)⁻¹; P<0·05) in pancreatic juice of pigs fed the autoclaved Nutrisoy diet, which corresponded with the increase in the secretion of protein-bound amino acids. There was also an increase in the total secretion of free amino acids in pancreatic juice. These studies show no effect of SBTI on the total enzyme activities in pancreatic juice of growing pigs. © 1998 SCI.     

Protein Contents,Amino Acid Compositions and Nitrogen-to-Protein Conversion Factors for Cassava Roots

Root protein contents of 15 cassava varieties ( Manihot esculenta Crantz) ranged from 5 to 19 g kg⁻¹ dry matter. Intervarietal differences in amino acid profiles of cassava roots were evident. Differences in the levels of aspartic acid, glutamic acid and arginine were most notable. The nitrogen-to-protein conversion factors ( k _AA ) based on nitrogen recovered from total amino acid analyses including ammonia ranged from 4·75 to 5·87, showing that the traditional conversion factor of 6·25 was not valid for cassava root proteins. Conversion factors ( k _P ) for 15 cassava varieties based on Kjeldahl nitrogen ranged from 2·49 to 3·67. Therefore an average k _P value of 3·24±0·31 may provide a better estimate of the protein content in cassava roots.     

The sequence of a 24 152 bp segment from the left arm of chromosome XIV from Saccharomyces cerevisiae between the BNI1 and the POL2 genes

In the framework of the European Union programme for sequencing the genome of Saccharomyces cerevisiae we have determined the nucleotide sequence of a region of 24 152 bp located on the left arm of chromosome XIV between the BNI1 and the POL2 genes. The sequence was obtained by directed sequence analysis using a mixture of ExoIII and primer walking strategies. Subsequent analysis revealed 13 open reading frames (ORFs) including four small ORFs completely internal to, or partly overlapping with, other ORFs. Five of these ORFs have been described previously (BNI1, APL1, LYP1, PIK1, POL2) and thus 74·8% of the 24 152 bp were already present in the databases prior to this sequencing effort. Interestingly, all 13 identified ORFs are characterized by a low codon adaptation index (0·04–0·22). In addition, this region of chromosome XIV shows an unusually high gene density with about 88% of coding DNA. This amounts to one gene per 2177 bp, which is significantly above the average gene length (about 1500 bp). For eight ORFs considerable homologies to ‘Expressed Sequence Tags’ derived from human cDNAs located in the XREF database could be identified. The complete nucleotide sequence of the 24 152 bp segment has been deposited in the EMBL data library under the Accession Number X92494.     

Sequencing and analysis of 51·6 kilobases on the left arm of chromosome XI from Saccharomyces cerevisiae reveals 23 open reading frames including the FAS1 gene

We have sequenced two segments containing a total of 51·6 kb of the left arm from chromosome XI of Saccharomyces cerevisiae. The first segment of 38·5 kb contains 18 open reading frames (ORFs) of more than 100 amino acid residues. Five ORFs encode known yeast genes, including the fatty acid synthase gene (FAS1). Three new yeast genes were discovered with homologies to non-yeast genes and ten new genes without homologies to any known sequences. The second segment of 13 kb contains five ORFs with two known yeast genes and three unknown genes. The sequences from cosmid pUKG041 were obtained entirely with the walking primer strategy resulting in a very low overall sequence redundancy of 2·8 and an average reading length of 443 bases.     

Chromosomal DNA patterns and gene stability of Pichia pastoris

We have clearly resolved four chromosomal bands from four Pichia pastoris (Komagataella pastoris) strains by using contour-clamped homogeneous electric field gel electrophoresis. The size of the P. pastoris chromosomal bands ranged from 1·7 Mb to 3·5 Mb and total genome size was estimated to be 9·5 Mb to 9·8 Mb; however, chromosome-length polymorphisms existed among four strains. Thirteen cloned genes isolated from strain GTS115 were assigned to the separated chromosomes, revealing that different hybridization patterns were observed in the AOX2 and URA3 genes among strains. P. pastoris is frequently used as an efficient host for heterologous gene expressions. We analysed chromosomal stability of strain GTS115-derived recombinant cell expressing human serum albumin during serial cultivation under the condition of vegetative and non-selective growth. No chromosomal rearrangements were observed and the expression constructs integrated into the his4 locus on chromosome I were very stable even at 83 generations, suggesting that stable expression would be carried out even in large-scale fermentation. © 1998 John Wiley & Sons, Ltd.     

Nitrogen in browse species: ruminal degradability and post-ruminal digestibility measured by mobile nylon bag and in vitro techniques

This study determined nitrogen degradability and digestibility of rumen undegradable nitrogen using mobile nylon bag (MNB) and pepsin/pancreatin in vitro technique (IV) of 40 browse species. Thirty Ethiopian highland sheep fitted with rumen cannulae were used in nitrogen (N) degradability studies. Six steers fitted with rumen cannulae were used in preparation of 16-h and 24-h ruminal undegraded residues and four steers fitted with distal abomasal cannulae were used in MNB technique. The browses varied widely in nitrogen solubility (15–468 g kg⁻¹), potential degradability (223–976 g kg⁻¹), rate of degradation (0·13–24% h⁻¹) and effective degradability (135–821 g kg⁻¹). The apparent N digestibility (ND) of the rumen undegraded residues differed significantly (P<0·05) among browse species. No significant difference (P>0·05) was observed in ND of 16-h and 24-h residues. The ND of the 16-h residue varied from -218 to 759 g kg⁻¹ and 169 to 851 g kg⁻¹ for MNB and IV methods, respectively. Browse species with high tannin contents such as Acacia hockii, A horrida, A melanoxylon, A persiciflora, A salicina, A saligna and Flemingia macrophylla had high rumen by-pass and a low ND, while Sesbania spp and A nilotica with low tannin contents underwent rapid and extensive dry matter and nitrogen degradation in the rumen. Acacia sieberiana, Chamaecytisus palmensis, Erythrina spp, Gliricidia sepium, Samanea saman and Enterolobium cyclocarpum had high proportions of protein escaping rumen degradation (BP ) and with a high proportion of the by-pass protein digested in the intestine, therefore these browses had a high potential as protein supplements. The ND measured with the MNB were significantly lower (P<0·001) than by the IV method. The correlation between MNB and IV was high and significant (R²=0·89, P<0·0001) as also indicated by the regression equation (SE in parentheses): MNB=-22·8 (4·55)+1·0 (0·08)IV (RSD=10·56, R²=0·79, n=40, P<0·001). The intercept of the linear relationship obtained was different from zero while the slope was not different from unity. Multiple regression analysis suggested that some of the unexplained variation could be accounted for by either nitrogen, acid detergent fibre, total phenolics or neutral detergent fibre bound tannin levels in browses. The IV method is accurate for estimating digestibility of ruminally undegradable N, and hence its use would considerably reduce the need for delicate surgery and the elaborate procedures involving the MNB technique. © 1998 SCI.     

XIV. Yeast sequencing reports. Twelve open reading frames revealed in the 23·6 kb segment flanking the centromere on the Saccharomyces cerevisiae chromosome XIV right arm

The nucleotide sequence of 23·6 kb of the right arm of chromosome XIV is described, starting from the centromeric region. Both strands were sequenced with an average redundancy of 4·87 per base pair. The overall G+C content is 38·8% (42·5% for putative coding regions versus 29·4% for non-coding regions). Twelve open reading frames (ORFs) greater than 100 amino acids were detected. Codon frequencies of the twelve ORFs agree with codon usage in Saccharomyces cerevisiae and all show the characteristics of low level expressed genes. Five ORFs (N2019, N2029, N2031, N2048 and N2050) are encoded by previously sequenced genes (the mitochondrial citrate synthase gene, FUN34, RPC34, PRP2 and URK1, respectively). ORF N2052 shows the characteristics of a transmembrane protein. Other elements in this region are a tRNA^Pro gene, a tRNA^Asn gene, a τ₃₄ and a truncated δ₃₄ element. Nucleotide sequence comparison results in relocation of the SIS1 gene to the left arm of the chromosome as confirmed by colinearity analysis. The nucleotide sequence data reported in this paper will appear in the EMBL, GenBank and DDBJ Nucleotide Sequence Databases under the accession number X77395.     

Review: Pure non‐Saccharomyces starter cultures for beer fermentation with a focus on secondary metabolites and practical applications

Recently there has been increased interest in using non‐Saccharomyces yeasts to ferment beer. The worldwide growth of craft beer and microbreweries has revitalised the use of different yeast strains with a pronounced impact on aroma and flavour. Using non‐conventional yeast gives brewers a unique selling point to differentiate themselves. Belgian brewers have been very successful in using wild yeasts and mixed fermentations that often contain non‐Saccharomyces yeasts. Historically, ancient beers and beers produced before the domestication of commonly used Saccharomyces strains most likely included non‐Saccharomyces species. Given the renewed interest in using non‐Saccharomyces yeasts to brew traditional beers and their potential application to produce low‐alcohol or alcohol‐free beer, the fermentation and flavour characteristics of different species of non‐Saccharomyces pure culture yeast were screened for brewing potential (Brettanomyces anomalus and bruxellensis, Candida tropicalis and shehatae, Saccharomycodes ludwigii, Torulaspora delbrueckii, Pichia kluyveri, Zygosaccharomyces rouxii). Alcohol‐free beer is already industrially produced using S. ludwigii, a maltose‐negative species, which is a good example of the introduction of non‐Saccharomyces yeast to breweries. Overall, non‐Saccharomyces yeasts represent a large resource of biodiversity for the production of new beers and have the potential for wider application to other beverage and industrial applications. Almost all of the trials reviewed were conducted with varying fermentation parameters, which plays an important role in the outcome of the studies. To understand these impacts all trials were described with their major fermentation parameters. Copyright © 2016 The Institute of Brewing & Distilling     

Screening of new strains of Saccharomycodes ludwigii and Zygosaccharomyces rouxii to produce low‐alcohol beer

Low‐alcohol beer (0.5–1.2% v/v ethanol) is a less common brewing industry output than standard beer but there is an increasing interest in this product, as evidenced by increased attention to health and safety and government policies on alcohol and diet. The main challenge in the production of low‐alcohol beer is the achievement of a product as similar as possible to regular beer, particularly concerning the content of the volatile compounds. These compounds can be lost during the physical removal of alcohol by dialysis, reverse osmosis and vacuum rectification. Consequently, an alternative technique is the use of biological methods, which involve the employment of non‐conventional yeasts. In this paper, 11 non‐conventional yeast strains were tested for low‐alcohol beer production. The strains used belonged to two different species: Saccharomycodes ludwigii and Zygosaccharomyces rouxii. The beer samples produced by these strains were analysed for their ethanol content and main volatile compounds. The S. ludwigii strains were more suitable for brewing low‐alcohol beer, especially strain DBVPG 3010, which also showed a higher content of esters and a lower amount of diacetyl compared with previous reports. The Z. rouxii strains produced an ethanol and diacetyl content above the taste threshold. This screening project can be considered as a first step towards the production of low‐alcohol beer by means of new selected non‐conventional yeasts. Copyright © 2015 The Institute of Brewing & Distilling     

Proximate Composition and Seed Lipid Components of Sorghum Cultivars from Argentina

Seeds of 11 sorghum cultivars ( Sorghum bicolor ) from Argentina were analysed for proximate composition, fatty acids and sterols. Oil, protein, carbohydrate and ash contents varied between 41 and 66 g kg⁻¹, 111 and 156 g kg⁻¹, 670 and 730 g kg⁻¹ and 13·8 and 20·6 g kg⁻¹ of dry matter, respectively. Fatty acid profiles revealed that the major acids were palmitic (15·1–24·8%), oleic (29·9–41·8%) and linoleic (35·9–51·3%). Unsaponifiable matter was examined for sterols. Sitosterol was the prominent component in all cultivars (43·8–57·9%), followed by campesterol (18·7–29·1%) and stigmasterol (12·4–20·5%).     

IV. Yeast sequencing reports. New open reading frames,one of which is similar to the nifV gene of Azotobacter vinelandii,Found on a 12·5 kbp fragment of chromosome IV of Saccharomyces cerevisiae

The nucleotide sequence of a 12·5 kbp segment of the left arm of chromosome IV is described. Five open reading frames (ORFs) longer than 100 amino acids were detected, all of which are completely confined to the 12·5 kbp region. Two ORFs (D1271 and D1286) correspond to previously sequenced genes (PPH22 and VMA1 or TFP1, respectively). ORF D1298 shows the characteristics of α-isopropylmalate and homocitrate synthase genes and is similar to the nifV gene of Azotobacter vinelandii. Two more ORFs have no apparent homologue in the data libraries. Conversely, two smaller ORFs of 25 and 85 amino acids encoding the ribosomal protein YL41A and an ATPase inhibitor, respectively, were detected. Although a substantial part of the 12·5 kbp fragment apparently lacks protein-coding characteristics, no other elements, such as tRNA genes or transposons, were found. The nucleotide sequence data reported in this paper will appear in the EMBL, GenBank and DDBJ Nucleotide Sequence Databases under the Accession Number X83276.     

An 18·3 kb DNA Fragment from Yeast Chromosome VII Carries Four Unknown Open Reading Frames,the Gene for an Asn Synthetase,Remnants of Ty and Three tRNA Genes

An 18·3 kb DNA segment from yeast Saccharomyces cerevisiae chromosome VII encompasses the previously characterized MEP1, NUP57 and PPT1 genes as well as seven new open reading frames (ORFs) of at least 100 residues. G6358 is an ubiquitous glutamine-dependant asparagine synthase. G6362 is a membrane protein highly homologous to a protein of unknown function in the yeast Schizosaccharomyces pombe. Three ORFs (G6324, G6335 and G6365) have no significant homology with previously reported proteins or characteristic motifs. G6321 and G6359, enclosed in longer ORFs, are not likely to be coding. The segment also contains tRNA genes for Asn, Arg and Ile as well as a sigma element and two solo deltas. ORFs and genetic elements are named according to a preliminary working nomenclature. The sequence is recorded in GenBank^TM/EMBL under Accession Number X83099.©1997 John Wiley & Sons, Ltd.     

Assessment of Phenolics-Related Antinutritive Levels using the In Vitro Gas Production Technique: A Comparison Between Different Types of Polyvinylpolypyrrolidone or Polyethylene Glycol

The use of different types of phenolic binding agents (PBA) in conjunction with the in vitro gas production technique for the assessment of phenolic related antinutritive factors in browse were compared. During a grazing trial by goats, three fractions, grazed leaves (GL), ungrazed leaves (UL) or stems of ungrazed leaves (US) of Robinia pseudoacacia, together with three harvests of leaves of Cistus incanus and a summer harvest of Fraxinus ornus or Carpinus duinensis were analysed for total extractable phenols (TEPH), total extractable tannins (TETa), condensed tannins (vanillin–HCl) (TECTa) and extractable and total proanthocyanidins (TEPAs and TOPAs). Gas production from the samples with or without adding insoluble polyvinylpolypyrrolidone (IPVP), soluble PVP or polyethylene glycol of different molecular weights was measured. The kinetics of gas production were determined using the equation p=a+b (1-e^−ct). The effects of addition of the PBAs were assessed as percentage changes in the rate and volume of gas production or concentration of volatile fatty acids (VFA). Levels (mg g⁻¹ DM) of TEPH varied from 4·9 to 100·4, TETa from 0·6 to 58·0, TECTa from 1·0 to 64·6, and TEPas or TOPAs from 5·7 to 283·0 and from 12·4 to 331·4. Except for PVP360 which depressed fermentation, addition of 200–500 mg of the other PBAs to rumen liquor/buffer or a tannin free hay, did not affect (P>0·05) fermentation. The highest increase in gas production was achieved with PEG4, PEG8 and PEG10 followed by PVP10, PVP40 and IPVP after 12–24 h incubation. The percentage increase in gas production as a result of adding the PEGs was best associated (r=0·83–0·96; P<0·01) with the higher concentrations of total VFAs after 96 h incubation and was also best related (r=0·89–0·91; P<0.01) to the levels of extractable condensed tannins (TECTa and TEPAs) in the browse. It was concluded that PEGs were more effective than PVPs in eliminating phenolic related antinutritive factors and would be preferred for use in conjunction with the gas technique for the assessment of phenolic related antinutritive factors in feeds.     

Human Colonic Bacterial Degradability of Dietary Fibres from Sea-Lettuce (Ulva sp)

Sea-lettuce (Ulva sp) is one of the commonly consumed seaweeds which contains 16·5% of water-soluble and 13·3% insoluble dietary fibres. Since physiological effects of fibres are partly related to their colonic bacteria fermentability, Ulva sp and its constitutive soluble and insoluble fibres were incubated with faecal bacteria in an in vitro batch fermenter system. After 24 h of incubation, 32·0±0·4%, 25·9±0·4% and 50·9±7·4% of Ulva, soluble and insoluble fibres constitutive sugars, respectively, were degraded. Consequently, Ulva and its soluble fibre, ulvan, are poorly fermented by colonic bacteria. The constitutive sugars, rhamnose and glucuronate and the aldobiouronate β-D -glucuronosyluronate-(1,4)-L -rhamnose of the glucuronoxylorhamnan sulphate present in the soluble fibre are highly fermented. Chemical desulphation and/or carboxyl group reduction did not modify this fermentation behaviour. Thus, the particular chemical structure of ulvan is responsible for the resistance of this polysaccharide and of Ulva to colonic bacterial fermentation. As a physiological consequence of this particular behaviour, consumption of dietary fibres from sea-lettuce could be expected to act mainly as bulking agents with little effect on nutrient metabolism due to colonic bacterial fermentation products (short-chain fatty acids). © 1997 SCI.     

The sequence of 36·8 kb from the left arm of chromosome XIV reveals 24 complete open reading frames: 18 correspond to new genes,one of which encodes a protein similar to the human myotonic dystrophy kinase

We have determined the complete nucleotide sequence of a 36·8 kb segment from the left arm of chromosome XIV carried by the cosmid 14–11. The sequence encodes the 5′ coding region of the PSD1 gene, the 3′ coding region of an unknown gene and 24 complete open reading frames, of which 18 correspond to new genes and six (SKO1, SCL41A, YGP1, YCK2, RPC31 and MFA2) have been sequenced previously. Of the 24 new genes, five show significant similarities to sequences present in the databanks. These include elongation factors 2 and the human myotonic dystrophy kinase. The sequence has been deposited in the EMBL databank under the Accession Number X92517.     

Effect of Yeast Culture Supplement on Ruminal Microbial Populations and Metabolism in Buffalo Calves Fed a High Roughage Diet

The effect of Saccharomyces cerevisiae yeast culture (YC, Yea-Sacc 1026) as a supplement to the high-roughage diet of buffalo calves on the rumen microbial populations, fermentation pattern and in sacco dry matter disappearance of dietary constituents was examined. A control group was fed a diet consisting of, on a dry matter basis, 2·12 kg bajra (Pennisetum typhoides) hay and 0·45 kg groundnut cake per day per calf, while the treatment group had the same diet plus 5 g YC. After feeding for 6 weeks, inclusion of YC was stopped and both groups were given the control diet for 2 weeks. At week 4 the pH in the rumen fluid (RF) was significantly higher (P<0·05) up to 6 h post-feeding in the treatment group compared with the control group. The concentrations of total, total viable and cellulolytic bacteria were increased by 41·0 (P<0·05), 33·5 and 57·4% (P<0·01), respectively, with YC supplement. The concentration of total volatile fatty acids (P<0·05), particularly at 4 h post-feeding (P<0·01) and acetate (P<0·01) and acetate to propionate ratio (P<0·05) were higher in the treatment compared with the control group. On YC supplementation, the concentration of NH₃-N was decreased (P<0·05) while that of TCA-precipitable protein in RF was marginally but non-significantly increased. Withdrawal of YC from the diet reversed these effects and the rumen variables returned to values close to control levels after 2 weeks. The in sacco dry matter disappearance of dietary components was higher in the treatment compared with the control group, particularly during the first 24 h of incubation. © 1997 SCI.     

VI. Yeast sequencing reports. Sequencing of an 18·8 kb fragment from Saccharomyces cerevisiae chromosome VI

The nucleotide sequence of lambda phage clone 4121, which contains the 18·8 kb fragment of Saccharomyces cerevisiae chromosome VI left arm, was determined. This sequence had seven open reading frames (ORFs), four of which were identical to known genes (ACT1, YPT1, TUB2 and RPO41). Another three ORFs (4121orfR003, 4121orfR004 and 4121orfRN001) were highly homologous to FET3 multi-copper oxidase, glucose transport protein, and hypothetical protein of YIL106w on chromosome IX, respectively. 4121orfRN01 is suggested to contain an intron. The sequence has been submitted to DDBJ/EMBL/GenBank data library under Accession Number D44598.     

Combined Effect of Drying Time and Slice Thickness on the Solar Drying of Okra

The effect of slice thickness and drying time on colour, viscosity, microbial load, moisture, crude fibre, vitamin C and ash contents of okra (Hibiscus esculentus) during solar drying was studied using three slice thicknesses (5·0 mm, 10·0 mm, 15·0 mm) obtained from a survey and five drying times (0, 24, 48, 72 and 96 h). The results showed that slice thickness had a significant effect (P<0·01) on moisture, crude fibre and ash contents but not on vitamin C content, viscosity, colour and microbial load. However, the effect of drying time was highly significant (P<0·01) on all the parameters determined. The combined effects of slice thickness and drying time were observed to be highly significant (P<0·05) on ash, crude fibre and moisture contents, viscosity and microbial load but had no significant effect (P<0·05) on colour and vitamin C content. There was a strong correlation between moisture content and ash (R=-0·926), crude fibre (R=-0·94), vitamin C contents (R=0·928) and viscosity (R=-0·963) in all samples during drying. The study showed that a slice thickness of 10·0 mm and a drying time of 48 h was suitable for the solar drying of okra. © 1997 SCI.     

Sequence Analysis of 203 Kilobases from Saccharomyces cerevisiae Chromosome VII

The nucleotide sequences of five major regions from chromosome VII of Saccharomyces cerevisiae have been determined and analysed. These regions represent 203 kilobases corresponding to approximately one-fifth of the complete yeast chromosome VII. Two fragments originate from the left arm of this chromosome. The first one of about 15·8 kb starts approximately 75 kb from the left telomere and is bordered by the SKI8 chromosomal marker. The second fragment covers the 72·6 kb region between the chromosomal markers CYH2 and ALG2. On the right chromosomal arm three regions, a 70·6 kb region between the MSB2 and the KSS1 chromosomal markers and two smaller regions dominated by the KRE11 marker and another one in the vicinity of the SER2 marker were sequenced. We found a total of 114 open reading frames (ORFs), 13 of which were completely overlapping with larger ORFs running in the opposite direction. A total of 44 yeast genes, the physiological functions of which are known, could be precisely mapped on this chromosome. Of the remaining 57 ORFs, 26 shared sequence homologies with known genes, among which were 13 other S. cerevisiae genes and five genes from other organisms. No homology with any sequence in the databases could be found for 31 ORFs. Furthermore, five Ty elements were found, one of which may not be functional due to a frame shift in its Ty1B amino acid sequence. The five chromosomal regions harboured five potential ARS elements and one sigma element together with eight tRNA genes and two snRNAs, one of which is encoded by an intron of a protein-coding gene. © 1997 by John Wiley & Sons, Ltd.