Regulation of the activity of alcohol dehydrogenase isozymes during the development of the maize kernel

Summary The relative activities of alcohol dehydrogenase isozymes have been studied during the development of the endosperm and scutellum of heterozygous Adh ₁ ^F /Adh ₁ ^S maize kernels. The products of the Adh ₁ ^F allele are found earlier than the products of the Adh ₁ ^S allele in both the scutellum and the endosperm. A second gene (Adh _r )which controlsthe activity level of ADH is active in the scutellum only. The Adh _r ^N allele specifies increase in the relative activity of the Adh ₁ ^S products from 26 to 38 days after pollination. This increase is prevented by the Adh _r ^L allele which is dominant. These results ar discussed on the basis of the limited factor hypothesis proposed recently by Schwartz (1971) for the regulation of the Adh ₁gene in maize.     

Dependence of the Composition of the Avermectin Complex of Streptomyces avermitilis on the Glucose Content in the Medium

The effects of the glucose concentration in the medium and O-methyl-L-threonine resistance on the ratio of components of the avermectin complex produced by Streptomyces avermitilishave been studied. Glucose deficiency increases the ratio of components A and ain the complex, while decreasing that of components 1. A mutation that renders the microorganisms resistant to O-methyl-L-threonine (an analogue of isoleucine) increases the ratio of components a in the complex, while decreasing that of components 1. The distribution of aand b in fractions 1and 2 remains constant: the values of the ratio a/b in the fractions amount, respectively, to 1 : 1 and 2 : 1. The relation of the variations in the composition of the avermectin complex to changes in the carbohydrate metabolism of the producer stain, underlain by availability of the source of carbon, is discussed.     

The effect of the r a and r b loci on the lipid content of the seed of Pisum sativum

Summary The lipid content of seed from a set of isogenic lines for the R _a : r _a locus has been determined; the results show that this locus as well as affecting the starch, sugar and storage protein content and composition, also has a marked effect on the lipid content of the seed. Genotypes having different combinations of alleles at the r _a and r _b loci have also been examined; an r _a r _a r _b r _b , genotype had 5.57% purified total lipid in its seed — a more than 2-fold increase over that found in the round-seeded varieties (R _a R _a R _b R _b ) usually grown for the dry sed crop.     

Theoretical studies on the role of food exploitation for the competition of scaamble type

A model was made to clarify the basic processes of competition to occur among larvae by the exploitation as defined byBakker (1969). It was found that this model is applicable to the experimental results on the food exploitation among Droshophila larvae obtained byBakker (1961). In the model the preimaginal stage is divided into two periods;T_f which is the time that a group of larvae spends in exhausting the food after hatching, and T_s which is the duration of the starvation period after T_f.T_f and then W_l (larval body weight) just after the end of T_f are decided by F_s (amount of food supplied per larva at larval hatching) and F_c (amount of food consumed per larva).T_f affects on the onset of T_s as well as R_l (rate of decrease in the individual body weight during T_s).W_a (weight of emerging adults) is gotten by a subtraction of R_l from W_l just after the end of T_f,R_e is affected directly by these components of W_l and R_l. As a result, W_a and R_e are expressed by functions of F_s. This model confirmed that the food exploitation lead to the competition of scramble type. Finally it was suggested that there exist some strategies which prevent ill-effects owing to the food exploitation.     

On the generalization of the logistic law of growth

This communication presents a discussion of some extensions of the formalism of Verhulst's simple logistics, which may constitute an autonomous growth model of a more general scope.For that purpose, the basis concept of growth diagram or trajectory is called upon, as it affords the graphic representation of the change in the growth variable y, using two relevant kinetic parameters: the instantaneous rate and the instantaneous acceleration. The two possible kinds of trajectories are in relation to the use of absolute (V = dyldt; = dV/dt) or relative (or specific) values (R = (1/y)(dy/dt); _R = dR/dt).In the case of simple logistics, the trajectory (V, ) allows 4 growth phases or states to be distinguished. The diagram (R, _R ) shows that the deceleration of the specific rate is not monotonous.In the case of Richards - Nelder's generalized logistics, the qualitative variation of the growth trajectory depends on the value of the dissymmetry parameter (occurrence of a critical value which determines the number of growth states).Blumberg's model is characterized by an analogous property and, moreover, can account for a non monotonous variation of the specific growth rate.     

Influence of rabbit cold adaptation on the depressor muscarinic cholinergic reaction of the arterial pressure of the hind limb vessels and the small intestine in situ and the systemic arterial pressure

Modification of the main parameters of cholinergic reactions in rabbits, i.e., of the specific sensitivity to agonists (EC ₅₀), maximal reaction values (P _m ) of arterial pressure in the hind limb vessels and small intestine in situ, and systemic arterial pressure after adaptation to cold for 1, 5, 10, and 30 days has been investigated. The depressor reaction to acetylcholine (muscarinic cholinergic receptors agonist) was established to correspond to the model p = (P _m A ⁿ )/(EC ₅₀ ⁿ + A ⁿ ) with n =1. In the control EC ₅₀ was equal to 0.85, 1.01, and 1.21 nmol/kg, while P _m equaled 100, 32.6, and 61.2 mm Hg for the hind limb vessels, small intestine in situ, and systemic arterial pressure, respectively.     

Analysis of the resistance of Aegilops squarrosa to the wheatgrass mildew fungus by using the gene-for-gene reationship

Summary Pm10 and Pm15, resistance genes to Erysiphe graminis f. sp. agropyri, are located on the D genome of common wheat. It was determined whether or not they were carried by existing lines of the D genome donor, Aegilops squarrosa, using the gene-for-gene relationship. Two lines of Ae. squarrosa tested (one was var. meyeri and the other was var. anathera) were susceptible to culture Tk-1 of E. graminis f. sp. tritici and were highly resistant to culture Ak-1 of E. graminis f. sp. agropyri. The two lines were inoculated with an F₁ population derived from the cross Ak-1 × Tk-1. Comparative analyses of the segregation patterns revealed that Ppm10 and Ppm15, avirulence genes corresponding to Pm10 and Pm15, respectively, are involved in the avirulence of Ak-1 on var. meyeri and var. anathera, respectively. According to the gene-for-gene relationship, var. meyeri and var. anathera were inferred to carry Pm10 and Pm15, respectively. Analysis with a synthetic hexaploid confirmed the inference.     

Evaluation of the Effect of Light Intensity on the Measurement of the Photosynthetic Rate in Plankton Microalgae by the Chlorophyll Fluorescence Method

The use of relative variable fluorescence (RVF) of chlorophyll, as measured in the presence of Diuron, an inhibitor of electron transfer, for the estimation of the photosynthetic activity of plankton microalgae was analyzed under a wide range of light intensities in the PAR region. Oxygen evolution rates (estimated by the method of light and dark bottles and the amperometric method), RVF, and chlorophyll a concentration were measured in parallel in natural algal cenoses and microecosystems. When the previously used regression equation, in the form A = b(F/F _d)C _chl I, where A is O₂ evolution rate (g/(m³ h), F/F _d is RVF (relative units), C _chl is chlorophyll a concentration (mg/m³), and I is light intensity (W/m²), was verified in the PAR region, we observed a nonlinear dependence of the correction coefficient b on I, which can be described by the formula b = 6.227 × 10³I. This result agrees with the hypothesis that chlorophyll a fluorescence quenching comprises photochemical (qQ) and energy (qE) components. On the basis of the energy model, we determined the upper limit b _max = 0.003 for light intensity range I< 4.4 W/m² and the lower limit b _min = 0.0003 for I = 400 W/m².     

Kinetics of the effect of amiloride on the permeability of the apical membrane of rabbit descending colon to sodium

Summary The effects of the addition of graded concentrations of amiloride, (A) _m , to the mucosal bathing solution on the permeability of the apical membrane of rabbit descending colon to Na (P _Na ^m ) were determined when the Na activity in the mucosal bathing solution, (Na) _m , was 18, 32 or 100mm.P _Na ^m was obtained from current-voltage relations determined on tissues bathed with a high-K serosal solution before and after the addition of a maximally inhibitory concentration of amiloride to the mucosal solution as described by Turnheim et al. (Turnheim, K., Thompson, S.M., Schultz. S.G. 1983.J. Membrane Biol. 76:299–309).The results indicate that: (1) As demonstrated previously (Turnheim et al., 1983),P _Na ^m decreases with increasing (Na) _m . (2)P _Na ^m also decreases hyperbolically with increasing (A) _m . Kinetic analyses of the effect of amiloride onP _Na ^m are consistent with the conclusions that: (i) the stoichiometry between the interaction of amiloride with apical membrane receptors that results in a decrease inP _Na ^m is one-for-one; (ii) there is no evidence for cooperativity between amiloride and these binding sites; (iii) the value of (A) _m needed to halveP _Na ^m at a fixed (Na) _m is 0.6–1.0 m; and, (iv) this value is independent of (Na) _m over the fivefold range studied.These findings are consistent with the notion that the sites with which amiloride interacts to bring about closure of the channels through which Na crosses the apical membrane arekinetically distinct from the sites with which (Na) _m interacts to bring about closure (i.e., self-inhibition). In short, the effects of (Na) _m and (A) _m onP _Na ^m in this tissue appear to be independent and additive.     

Seasonal study of the fungal biota of the fur of dogs

During a one year period, 944 dogs from the Municipal kennel of Barcelona were examined to detect animals with suspected dermatophytosis. Only a few animals (1.8%) presented skin lesions but none of them had dermatophytosis. A representative number of dogs without visible skin lesions (n=172), selected at random, were used to carry out a seasonal study of the mycobiota of their fur. Fifteen isolates belonging to the genera Microsporum and Trichophyton were isolated from 14 of the 172 (8.1%) dogs without lesions. The identity of these fungi was Microsporum gypseum (6/15), Trichophyton terrestre (4/15), M. canis (2/15), M. cookei (2/15) and Trichophyton ajelloi (1/15) (one strain each of M. gypseum and T. ajelloi were isolated from one dog). Species of Penicillium (% prevalence=89.5%), Alternaria (86.6%), Cladosporium (84.9%), Aspergillus (77.3%), Scopulariopsis (65.7%) and Chrysosporium (64.5%) were the most prevalent. No significant differences in the fungal biota were observed with respect to age, gender, hair length or between mixed and pure breed dogs. A large number of isolates, including species belonging to the genera Beauveria, Chrysosporium, Malbranchea and Scopulariopsis, that macroscopically and/or microscopically resemble dermatophytes and may be mistaken for them, produced a red color change in Dermatophyte Test Medium. No significant seasonal difference was detected among the isolates belonging to the the most frequently encountered genera, with the exception of Scopulariopsis (higher in summer and autumn) and Chrysosporium (higher in summer). Species from other genera, with lower occurrence also presented significant differences in their seasonal distribution. Arthrinium, Aureobasidium, Chaetomium and Phoma spp. presented maximum prevalence peaks in spring, Fusarium, Paecilomyces, Phoma and Rhizopus spp. in summer and Geotrichum and Mucor spp. in autumn. The Microsporum and Trichophyton species were more frequently isolated in summer.     

A review of oribatid mites of the family Suctobelbidae (Acariformes,Oribatida) from the caucasus

This paper summarizes the data on the oribatid mite fauna of the family Suctobelbidae Grandjean, 1954, recorded from the Caucasus. The distribution of 47 species of the genera Suctobelba Paoli, 1908, Suctobelbella Jacot, 1937, and Suctobelbila Jacot, 1937 in the territory of the Caucasus is shown. The following five new species and four new subspecies are described: Suctobelba cornigera sp. n., S. flagelliseta sp. n., S. scalpellata caucasica ssp. n., Suctobelbella (Suctobelbella) liacariformis sp. n., S. (S.) acutidens pilososetosa ssp. n., S. (S.) subcornigera maculata ssp. n., S. (Flagrosuctobelba) diversosetosa arilloi ssp. n., S. (F.) nana sp. n., and S. (F.) sensillinuda sp. n. Four species belonging to the genus Suctobelbella changed their status: S. (S.) acutidens duplex (Strenzke, 1950) stat. n., S. (S.) acutidens sarekensis (Forsslund, 1941) stat. n., S. (S.) subcornigera vera (Moritz, 1964) stat. n. and S. (Flagrosuctobelba) forsslundi moritzi Mahunka, 1987 stat. n. S. (S.) hammerae (Krivolutsky, 1965) was synonymized to S. (S.) acutidens duplex. The genus Suctobelbila and the species Suctobelbila dentata europaea Moritz, 1974, Suctobelba altvateri Moritz, 1970, S. atomaria Moritz, 1970, S. secta Moritz, 1970, Suctobelbella (S.) acutidens sarekensis, S. (S.) hastata Pankow, 1986, S. (S.) subcornigera vera stat. n., S. (Flagrosuctobelba) ancorhina Chinone, 2003, S. (F.) elegantula (Hammer, 1958), S (F.) flagellifera Chinone, 2003, S (F.) granifera Chinone, 2003, S. (F.) forsslundi moritzi Mahunka, 1987 stat. n., and S. (F.) multiplumosa (Hammer, 1979) are recorded from the Caucasus for the first time. A key to the species is given.     

Localization of neuropeptide Y-immunoreactive cells and fibres in the brain of the Japanese quail

Summary In the present study, we have demonstrated, by means of the biotin-avidin method, the widespread distribution of neuropeptide Y (NPY)-immunoreactive structures throughout the whole brain of the Japanese quail (Coturnix coturnix japonica). The prosencephalic region contained the highest concentration of both NPY-containing fibres and perikarya. Immunoreactive fibres were observed throughout, particularly within the paraolfactory lobe, the lateral septum, the nucleus taeniae, the preoptic area, the periventricular hypothalamic regions, the tuberal complex, and the ventrolateral thalamus. NPY-immunoreactive cells were represented by: a) small scattered perikarya in the telencephalic portion (i.e. archistriatal, neostriatal and hyperstriatal regions, hippocampus, piriform cortex); b) medium-sized cell bodies located around the nucleus rotundus, ventrolateral, and lateral anterior thalamic nuclei; c) small clustered cells within the periventricular and medial preoptic nuclei. The brainstem showed a less diffuse innervation, although a dense network of immunopositive fibres was observed within the optic tectum, the periaqueductal region, and the Edinger-Westphal, linearis caudalis and raphes nuclei. Two populations of large NPY-containing perikarya were detected: one located in the isthmic region, the other at the boundaries of the pons with the medulla. The wide distribution of NPY-immunoreactive structures within regions that have been demonstrated to play a role in the control of vegetative, endocrine and sensory activities suggests that, in birds, this neuropeptide is involved in the regulation of several aspects of cerebral functions.Abbreviations AA archistriatum anterius - AC nucleus accumbens - AM nucleus anterior medialis - APP avian pancreatic polypeptide - CNS centrai nervous system - CO chiasma opticum - CP commissura posterior - CPi cortex piriformis - DIC differential interferential contrast - DLAl nucleus dorsolateralis anterior thalami, pars lateralis - DLAm nucleus dorsolateralis anterior thalami, pars medialis - E ectostriatum - EW nucleus of Edinger-Westphal - FLM fasciculus longitudinalis medialis - GCt substantia grisea centralis - GLv nucleus geniculatus lateralis, pars ventralis - HA hyperstriatum accessorium - Hp hippocampus - HPLC high performance liquid chromatography - HV hyperstriatum ventrale - IF nucleus infundibularis - IO nucleus isthmo-opticus - IP nucleus interpeduncularis - IR immunoreactive - LA nucleus lateralis anterior thalami - LC nucleus linearis caudalis - LFS lamina frontalis superior - LH lamina hyperstriatica - LHRH luteinizing hormone-releasing hormone - LoC locus coeruleus - LPO lobus paraolfactorius - ME eminentia mediana - N neostriatum - NC neostriatum caudale - NPY neuropeptide Y - NIII nervus oculomotorius - NV nervus trigeminus - NVI nervus facialis - NVIIIc nervus octavus, pars cochlearis - nIV nucleus nervi oculomotorii - nIX nucleus nervi glossopharyngei - nBOR nucleus opticus basalis (ectomamilaris) - nCPa nucleus commissurae pallii - nST nucleus striae terminalis - OM tractus occipitomesencephalicus - OS nucleus olivaris superior - PA palaeostriatum augmentatum - PBS phosphate-buffered saline - POA nucleus praeopticus anterior - POM nucleus praeopticus medialis - POP nucleus praeopticus periventricularis - PP pancreatic polypeptide - PYY polypeptide YY - PVN nucleus paraventricularis magnocellularis - PVO organum paraventriculare - R nucleus raphes - ROT nucleus rotundus - RP nucleus reticularis pontis caudalis - Rpc nucleus reticularis parvocellularis - RPgc nucleus reticularis pontis caudalis, pars gigantocellularis - RPO nucleus reticularis pontis oralis - SCd nucleus subcoeruleus dorsalis - SCv nucleus subcoeruleus ventralis - SCNm nucleus suprachiasmaticus, pars medialis - SCNl nucleus suprachiasmaticus, pars lateralis - SL nucleus septalis lateralis - SM nucleus septalis medialis - Ta nucleus tangentialis - TeO tectum opticum - Tn nucleus taeniae - TPc nucleus tegmenti pedunculo-pontinus, pars compacta - TSM tractus septo-mesencephalicus - TV nueleus tegmenti ventralis - VeL nucleus vestibularis lateralis - VLT nucleus ventrolateralis thalami - VMN nucleus ventromedialis hypothalami A preliminary report of this study was presented at the 15th Conference of European Comparative Endocrinologists, Leuven, Belgium, September 1990     

Limiting similarity and the form of the competition coefficient

The question of whether there is a limit to the similarity of competing species has previously been investigated by a number of authors. These studies have all used the Lotka-Volterra model of competition, and have assumed that the competition coefficient α_ij may be calculated using the expression, α_ij = ∝ U_i(R) U_j(R) dR/∝ (U_i(R))² dR. In this paper, the generality of this formula is questioned and two alternative expressions for α_ij are proposed. When these expressions are used in an analysis of limiting similarity, qualitatively different conclusions emerge regarding the existence and nature of this limit, using either deterministic or stochastic models. The relevance of these findings to theories of character convergence and similarity barriers is discussed. The available field evidence does not strongly support the validity of the formula for α_ij used in previous studies. Since a given method of calculating α_ij must be derived from a higher level model, it is suggested that the Lotka-Volterra model is not sufficient in an investigation of limiting similarity.     

Hypoxia tolerance of the mummichog: the role of access to the water surface

Low dissolved oxygen (DO) had a significant effect on specific growth rate (G_S), length increment (I_L) and haematocrit (Hct) of the mummichog Fundulus heteroclitus. Regardless of access to the water surface, F. heteroclitus maintained high growth rates (G_S and I_L) at DO concentrations as low as 3 mg O₂ l^?1. With access to the water surface, both G_S and I_L of F. heteroclitus decreased by c. 60% at 1·0 mg O₂ l^?1 compared to all higher DO treatments. When denied access to the water surface, a further decrease in G_S (c. 90%) and I_L (c. 75%) was observed at 1 mg O₂ l^?1. There was no effect of diel‐cycling DO (1–11 mg O₂ l^?1) with or without surface access on G_S, I_L or Hct of F. heteroclitus. Similar trends between G_S and faecal production across DO treatments suggest that decreased feeding contributed significantly to the observed decrease in growth rate. Haematocrit was significantly elevated at 1 mg O₂ l^?1 for fish with and without access to the water surface. Increased Hct, however, was not sufficient to maintain high G_S or I_L at severely low DO. When permitted to respire in the surface layer, however, F. heteroclitus was capable of maintaining moderate growth rates at DO concentrations of 1 mg O₂ l^?1 (c. 15% saturation). Although aquatic surface respiration (ASR) was not quantified in this study, F. heteroclitus routinely swam in contact with the water surface and performed ASR at DO concentrations ≤3 mg O₂ l^?1. No hypoxia‐related mortality was observed in any DO or surface access treatment for as long as 9 days. This study demonstrates that surface access, and thus potential for ASR, plays an important role in providing F. heteroclitus substantial independence of growth rate over a wide range of low DO conditions commonly encountered in shallow estuarine environments.     

Involvement of IS1 in the dissociation of the r-determinant and RTF components of the plasmid R100.1

Summary Detailed mapping localized the PHO 1 mutation between the OLI 2 and OLI 4 loci on mitochondrial DNA of Saccharomyces cerevisiae.In its mitochondrially integrated form, the PHO 1-ATPase³ was difficult to identify either immunologically or by specific inhibitors like oligomycin and DCCD. Solubilization by Triton X-100 allowed unambiguuous identification of this enzyme as an authentic mitochondrial ATPase. However, Triton extraction produced a 2 to 3 fold enhancement of the PHO 1-ATPase activity which also became drastically cold-sensitive. The wild type ATPase was neither activated nor made cold-labile by solubilization, and retained full sensitivity to oligomycin and DCCD.Sucrose gradient analysis of the Triton-extracted ATPase from wild type, PHO 1 mutant and rho ^- strains showed a density difference between the solubilized PHO 1-and wild type ATPase, and similarity between solubilized PHO 1-and rho ^- ATPase (F₁).Whole cells of the PHO 1 mutant present considerably increased respiration rates.Comparison of oligomycin-sensitivity in whole cells, coupled isolated mitochondria and membrane-bound ATPase indicates a contrast between oligomycin-resistance of the ATPase and oligomycin-sensitivity of in vivo or in vitro coupling systems, which might characterize the products of this region of mitochondrial DNA.     

Supplement to the hepatic flora of the Shetland Islands

Background: Grasslands have only a few dominants and most of the diversity consists of subdominants. Because dominants differ widely in phenology and resource use, dominants may control the recruitment and establishment of other species.

Aims: To explore the relationship between the identity of the dominant species and successional vegetation changes in grassland communities.

Methods: The compositional change over 23 years in 1900 permanent plots dominated by four grasses (Andropogon gerardii, Elymus repens, Poa pratensis and Schizachyrium scoparium) was examined within 19 old fields in Minnesota. Fields were abandoned 1–56 years before sampling. Rate of directional change and degree of compositional dissimilarity were determined.

Results: Non-natives, P. pratensis and E. repens, were associated with either no or a slow directional change. Elymus repens was associated with high dissimilarity and P. pratensis with intermediate dissimilarity. Natives, A. gerardii and S. scoparium, were associated with compositional change that followed expectations based on field age. The rate of directional change and degree of dissimilarity between sampling intervals was lower for A. gerardii relative to S. scoparium, the only species to be associated with strong directional change.

Conclusions: Dominance by non-native grass species may impede traditional successional processes and result in a community composition quite dissimilar from native prairies.     

Reconstruction of the last marine connectivity of the Zagros basin,based on fossil evidences of the clastic-dominated Bakhtiari Formation

In this study, new paleontology and lithology foundations on the Bakhtiari Formation were obtained from Shalamzar area in Zagros basin. A depositional mollasic cycle was divided into Bk1, Bk2 and Bk3 units from the base to the top of the Formation. Bk2, with limestone- and mudstone-dominated deposits, was found to alternate with conglomerates and form a marine succession between the two limestone clast-supported conglomeratic continental units. A diverse fossil association has been described for the first time and consists of foraminifera (Oolina spp., Oolina hexagona, Textularia spp., Spiroloculina spp., Peneroplis spp., Elphidium spp., Planulina sp., Amphistegina spp., Lagena spp. Globigerina spp., Globigerinoides spp., Uvigerina spp., Triloculina spp., Quinqueloculina spp., Spiroloculina spp. Nodosariid., Orbitina spp., Borelis melo, Bolivina spp. and Miogypsina spp.), a gastropod community of Strombus spp., Potamides spp., Turitella spp., Cyprea cf. persica and Pleurotomaria sp. and a higher energy colony of scleractinian corals comprising Porites branching, Porites-encrusting massive Favites spp., Favia spp., Tarbellastrea spp. and Acropora spp. The early–middle Miocene marine level of the Bakhtiari Formation, confirms a nearshore accommodation through a middle shelf and an open coastal lagoon (inner shelf) within a fluvial-dominated delta or open estuary during the last presence of a marine trough in the Zagros basin. This saline to hypersaline shallow marine regime was probably dominated in tropical to subtropical conditions. Palaeobiogeography analysis reflects a last seaway faunal exchange between the area and early–middle Miocene basins of Pakistan, India, Australia, Turkey, Greece, Romania Algeria, Egypt, Italy, France, Portugal and Austrian/Hungarian border, which reconstructs a shallow junction between Zagros basin and Mediterranean Tethys and Indo-pacific Ocean during Burdigalian–Langhian (Badenian) before the terminal Tethyan event in late middle Miocene and Tortonian.     

Enhancing the flux of D-glucose to the pentose phosphate pathway in Saccharomyces cerevisiae for the production of D-ribose and ribitol

Phosphoglucose isomerase-deficient (pgi1) strains of Saccharomyces cerevisiae were studied for the production of D-ribose and ribitol from D-glucose via the intermediates of the pentose phosphate pathway. Overexpression of the genes coding for NAD⁺-specific glutamate dehydrogenase (GDH2) of S. cerevisiae or NADPH-utilising glyceraldehyde-3-phosphate dehydrogenase (gapB) of Bacillus subtilis enabled growth of the pgi1 mutant strains on D-glucose. Overexpression of the gene encoding sugar phosphate phosphatase (DOG1) of S. cerevisiae was needed for the production of D-ribose and ribitol; however, it reduced the growth of the pgi1 strains expressing GDH2 or gapB in the presence of higher D-glucose concentrations. The CEN.PK2-1D laboratory strain expressing both gapB and DOG1 produced approximately 0.4 g l⁻¹ of D-ribose and ribitol when grown on 20 g l⁻¹ (w/v) D-fructose with 4 g l⁻¹ (w/v) D-glucose. Nuclear magnetic resonance measurements of the cells grown with ¹³C-labelled D-glucose showed that about 60% of the D-ribose produced was derived from D-glucose. Strains deficient in both phosphoglucose isomerase and transketolase activities, and expressing DOG1 and GDH2 tolerated only low D-glucose concentrations (≤2 g l⁻¹ (w/v)), but produced 1 g l⁻¹ (w/v) D-ribose and ribitol when grown on 20 g l⁻¹ (w/v) D-fructose with 2 g l⁻¹ (w/v) D-glucose.     

Adaptive significance of the action of the Drosophila melanogaster alcohol dehydrogenase locus through the heat shock protein system

Four Drosophila melanogaster strains, each homozygous for one of the two major ADH aliozymes, Fast and Slow (Adh ^F1, Adh ^S , Adh ^F2 and Adh ^S2) were used to study the interaction of the Adh locus with ethanol and temperature. The separate and especially the combined effects of these two parameters allow the conclusion that the Adh locus of D. melanogaster intervenes in the adaptation process through the heat shock protein system.