bluuebunny/crossref_metadata_2025 huggingface dataset:
A truncated form of DNA topoisomerase IIβ associates with the mtDNA genome in mammalian mitochondria
Authors: Low Robert L. , Orton Shayla , Friedman David B.
Published: October 2003

Despite the likely requirement for a DNA topoisomerase II activity during synthesis of mitochondrial DNA in mammals, this activity has been very difficult to identify convincingly. The only DNA topoisomerase II activity conclusively demonstrated to be mitochondrial in origin is that of a type II activity found associated with the mitochondrial, kinetoplast DNA network in trypanosomatid protozoa [Melendy, T., Sheline, C., and Ray, D.S. (1988) Cell55, 1083–1088; Shapiro, T.A., Klein, V.A., and Englund, P.A. (1989) J. Biol. Chem.264, 4173–4178]. In the present study, we report the discovery of a type DNA topoisomerase II activity in bovine mitochondria. Identified among mtDNA replicative proteins recovered from complexes of mtDNA and protein, the DNA topoisomerase relaxes a negatively, supercoiled DNA template in vitro, in a reaction that requires Mg2+ and ATP. The relaxation activity is inhibited by etoposide and other inhibitors of eucaryotic type II enzymes. The DNA topoisomerase II copurifies with mitochondria and directly associates with mtDNA, as indicated by sensitivity of some mtDNA circles in the isolated complex of mtDNA and protein to cleavage by etoposide. The purified activity can be assigned to a ≈ 150‐kDa protein, which is recognized by a polyclonal antibody made against the trypanosomal mitochondrial topo II enzyme. Mass spectrometry performed on peptides prepared from the ≈ 150‐kDa protein demonstrate that this bovine mitochondrial activity is a truncated version of DNA topoisomerase IIβ, one of two DNA topoisomerase II activities known to exist in mammalian nuclei.
Identification of proNeuropeptide FFA peptides processed in neuronal and non‐neuronal cells and in nervous tissue
Authors: Bonnard Elisabeth , Burlet‐Schiltz Odile , Monsarrat Bernard , Girard Jean‐Philippe , Zajac Jean‐Marie
Published: October 2003

Peptides which should be generated from the neuropeptide FF (NPFF) precursor were identified in a neuronal (human neuroblastoma SH‐SY5Y) cell line and in COS‐7 cells after transient transfection of the human proNPFFA cDNA and were compared with those detected in the mouse spinal cord. After reverse‐phase high performance liquid chromatography of soluble material, NPFF‐related peptides were immunodetected with antisera raised against NPFF and identified by using on‐line capillary liquid chromatography/nanospray ion trap tandem mass spectrometry. Neuronal and non‐neuronal cells generated different peptides from the same precursor. In addition to NPFF, SQA‐NPFF (Ser‐Gln‐Ala‐Phe‐Leu‐Phe‐Gln‐Pro‐Gln‐Arg‐Phe‐amide) and NPAF were identified in the human neuroblastoma while only NPFF was clearly identified in COS‐7 cells. In mouse, in addition to previously detected NPFF and NPSF, SPA‐NPFF (Ser‐Pro‐Ala‐Phe‐Leu‐Phe‐Gln‐Pro‐Gln‐Arg‐Phe‐amide), the homologous peptide of SQA‐NPFF, were characterized. These data on intracellular processing of proNeuropeptide FFA are discussed in regard to the known enzymatic processing mechanisms.
Azotobacter vinelandii rhodanese
Authors: Melino Sonia , Cicero Daniel O. , Orsale Maria , Forlani Fabio , Pagani Silvia , Paci Maurizio
Published: October 2003

Rhodanese is a sulfurtransferase which in vitro catalyzes the transfer of a sulfane sulfur from thiosulfate to cyanide. Ionic interactions of the prokaryotic rhodanese‐like protein from Azotobacter vinelandii were studied by fluorescence and NMR spectroscopy. The catalytic Cys230 residue of the enzyme was selectively labelled using [15N]Cys, and changes in 1H and 15N NMR resonances on addition of different ions were monitored. The results clearly indicate that the sulfur transfer is due to a specific reaction of the persulfurated Cys residue with a sulfur acceptor such as cyanide and not to the presence of the anions. Moreover, the 1H‐NMR spectrum of a defined spectral region is indicative of the status of the enzyme and can be used to directly monitor sulfur loading even at low concentrations. Selenium loading by the addition of selenodiglutathione was monitored by fluorescence and NMR spectroscopy. It was found to involve a specific interaction between the selenodiglutathione and the catalytic cysteine residue of the enzyme. These results indicate that rhodanese‐like proteins may function in the delivery of reactive selenium in vivo.
Inheritance of resistance to the ‘Kanpur’ race of Phytophthora drechsleri in pigeonpea
Authors: Singh I. P. , Chaudhary R. G. , Katiyar P. K. , Dua R. P. , Robbelen G.
Published: October 2003

Phytophthora drechsleri causes stem blight, which is one of the most serious diseases of pigeonpea. Eight races of this fungus have been identified, but the inheritance of resistance to all these races is not clear except for race P2. This study examined the inheritance of resistance to race ‘Kanpur’ (KPR) of P. drechsleri in eight crosses involving four resistant parents, viz.‘KPBR 80‐2‐1′, ‘KPBR 80‐2‐2′, ‘Hy 3C and ‘BDN 1′, and two susceptible parents, viz.‘Bahar’ and ‘PDA 10′. The reactions of the parental lines, and their F1, F2 and backcross generations were studied in an infected plot. In the F1 generation of all crosses, a susceptible reaction was observed that indicated dominance of susceptibility over resistance. The segregation pattern in F2 indicated that two homozygous recessive genes (pdr1pdr1pdr2pdr2) were responsible for imparting resistance in the parents, ‘KPBR 80‐2‐1’ and ‘KPBR 80‐2‐2′, and that a single homozygous recessive gene (pdrpdr) was responsible for resistance in the parents ‘Hy 3C and ‘BDN 1′. Therefore, ‘KPBR 80‐2‐1’ and ‘KPBR 80‐2‐2’ with two genes for resistance are better donors because the resistance transferred from them will be more durable compared with ‘Hy3C and ‘BDN1’ with only one gene for resistance.
All hermaphrodite progeny are derived by self‐pollinating the sunrise papaya mutant
Authors: Chan‐Tai C. , Yen C.‐R. , Chang L.‐S. , Hsiao C.‐H. , Ko T.‐S. , Weber W. E.
Published: October 2003

Self‐pollination of a hermaphroditic cultivar normally gives a ratio of 2 : 1 hermaphrodite to female papayas with genotypes M2m and mm, respectively. Much effort has been dedicated to marking the sexual types of papaya at the seedling stage to distinguish hermaphroditic from female papayas. A hermaphroditic papaya mutant (SR*) has been obtained, derived from the ‘Sunrise’ papaya cultivar mutant. Self‐pollination of the mutant resulted in all progenies being hermaphroditic. The genotype of the female was lethal, as a result of a lethal gene being linked to the mm female gene complex in this case. However, a 3 : 1 segregation ratio was obtained from the progeny of the hermaphroditic cultivar ‘Thailand’ crossed with SR*, indicating that all genotypes survived. Homozygous genotypes (M2M2) would be lethal according to Storey's model. Randomly selected F1 plants of the ‘Thailand’ SR* combination were self‐pollinated to obtain an F2 generation. The F2 segregation ratio suggested that the SR* mutant had a different form of the M2 allele, now designated as M@, which allowed the dominant M@M2 to survive in cross combinations. Genetic study has proved that SR* has the M@ml genotype, a new mutant. It is capable of producing all hermaphroditic papaya progenies.
Random amplified polymorphic DNA variation within and among meadow bromegrass progeny types
Authors: DE Araújo M. R. A. , Coulman B. , Somers D. , Ferdinandez Y. , Rakow G.
Published: October 2003

Ten meadow bromegrass genotypes tested as half‐sib (polycross, PX; open‐pollinated, OP) and selfed (S1) progenies were surveyed using random amplified polymorphic DNA. Fourteen primers, which produced 32 markers, were selected to determine the genotypes of 360 individuals from the three progeny tests. Analysis of molecular variance was performed in each progeny test, and genetic distances between genotypes and progeny types were determined. Among genotype genetic variation in half‐sib (PX and OP) progenies was similar. Genetic variation among genotypes for S1 progenies (30.5%) was about twice that found in the half‐sib progenies. Variation between individual S1 progenies ranged from 15.7% to 50.1%, while in the half‐sib progenies, the range was 6.9‐24.1%. Based on average distances between progeny types for a given genotype, OP and PX were closer to each other than to the S1. An analysis of variance of the molecular marker frequency occurrence was performed for 12 plants within each progeny type of each genotype. Marker frequencies, expressed in percentages, ranged from 10.7% to 84.3%. No significant differences were found for genotype and progeny type‐genotype interaction suggesting that all genotypes behave in a similar manner across the different progeny types.
Pleiotropic effect of the dwarfing gene d18‐k on cool tolerance at booting stage under the genetic background of an extremely cool‐tolerant line Norin‐PL8 in rice
Authors: Murai M. , KC H. B. , Gima N. , Jung C.
Published: October 2003

Norin‐PL8 (‘PL8’) is an extremely cool‐tolerant line of rice in Japan that contains genes for cool tolerance originating from a javanica landrace. It was investigated to see whether the dwarfing gene d18‐k (kotaketamanishiki dwarf) exerts its pleiotropic effect on enhancing the cool tolerance at the booting stage in the genetic background of PL8. The d18‐k isogenic line of the recurrent parent PL8 (D8), PL8, and two commercial cultivars ‘Hayayuki’ and ‘Kirara 397’ were used. For each line/cultivar, the 12°C‐5‐day treatment was conducted at various times during the booting stage. In addition to spikelet fertility, the ratio (%) of the fertilized‐spikelet number of each treated panicle to the varietal mean of fertilized‐spikelet number per panicle in the control (FS‐T/C) was adopted to estimate cool temperature damage. For FS‐T/C, the lines‐cultivars ranked in the order of D8 > PL8 > ‘Hayayuki’ > ‘Kirara 397’, reflecting their cool tolerances. D8 exceeded PL8 in both pollen grain number per anther in the control and as an indicator of pollen fertility after the treatment, as a result of the effects of d18‐k. Consequently, d18‐k can be used to develop super‐highly cool‐tolerant cultivars for cool‐weather areas.
Inheritance and chromosomal location of Septoria passerinii resistance introgressed from Hordeum bulbosum into Hordeum vulgare
Authors: Toubia‐Rahme H. , Johnston P. A. , Pickering R. A. , Steffenson B. J. , Graner A.
Published: October 2003

Septoria speckled leaf blotch (SSLB), caused by Septoria passerinii, has become one of the most serious diseases of barley in the Upper Midwest region of the USA. The recombinant line 36L5 derived from a backcross of the susceptible barley cultivar ‘Emir’ and a resistant Hordeum bulbosum parent Cb2920/4/Colch was found to be resistant to S. passerinii. Two doubled haploids derived from 36L5 were backcrossed to cv.‘Emir’ to obtain two BCF2 populations for determining the inheritance of resistance to S. passerinii. BCF2 progeny and BCF2:3 families were evaluated at the seedling stage in the greenhouse for reaction to S. passerinii. BCF2 progeny and BCF2:3 families from both crosses segregated 3 : 1 (resistant : susceptible), and 1:2:1 (resistant : segregating : susceptible), respectively, indicating that the H. bulbosum‐derived SSLB resistance is conferred by a single dominant gene. The H. bulbosum introgressions were positioned on chromosome 4HL by genomic and fluorescent in situ hybridizations (GISH and FISH, respectively) and by Southern hybridization with the rye repetitive sequence pSc119.2. These findings indicate that SSLB resistance in H. bulbosum has the potential to be transferred and utilized in barley breeding programs.
The use of microsatellite markers to determine the relative proportions of grain produced by cultivars and the frequency of hybridization in bread wheat mixtures
Authors: Fraj M. Belhaj , Falentin‐Guyomarc'h H. , Monod H. , Vallavieille‐Pope C. DE , Weber W. E.
Published: October 2003

Two polymorphic microsatellite markers were selected to identify 24 bread wheat cultivars commonly grown in France and to estimate the proportions of cultivar and hybrid grains in the harvests of four 4‐cultivar mixtures (CM 1‐4) planted in equal proportions in farmers’ fields. This technology was used not only to determine whether a mixture comprises the declared cultivars, but also whether there is any contamination with other cultivars, to identify the contaminants and to estimate their proportions. At harvest, the cultivar proportions ranged from 15 to 37%. Only in the mixture CM2 (‘Malacca’, ‘Somme’, ‘Renan’ and ‘Soissons’), did the cultivars contribute equally to the harvest. The other cultivar mixtures CM1 (‘Malacca’, ‘Somme’, ‘Renan’ and ‘Camp Remy’), CM3 (‘Malacca’, ‘Texel’, ‘Apache’ and ‘Aligre’) and CM4 (‘Malacca’, ‘Somme’, ‘Apache’ and ‘Virtuose’) showed significantly unequal cultivar proportions with ‘Somme’ dominating ‘Renan’ and ‘Camp Remy’ in CM1, and ‘Apache’ dominating ‘Malacca’ and ‘Aligre’ in CM3 and ‘Malacca’ in CM4. Similar cultivar proportions were measured with gliadin and glutenin markers in the mixtures CM3 and CM4, confirming the results with microsatellites. No contamination was found. Hybrids accounted for between 1.3 and 6.3% of the grains produced in the four cultivar mixtures.
New durum wheat with Hessian fly resistance from Triticum araraticum and T. carthlicum in Morocco
Authors: Nsarellah N. , Amri A. , Nachit M. M. , Bouhssini M. EL , Lhaloui S. , Lorenzoni C.
Published: October 2003

Hessian fly is an important pest of wheat on the North American continent and the temperate Mediterranean drylands. Yield losses caused by this insect in Morocco are the heaviest in the Mediterranean region and are estimated to be 36% on average. Genetic resistance to Mediterranean Hessian fly biotypes has not been found in durum wheat, although large numbers of durum accessions were screened. Genes for resistance were found in common wheat; some of which are transferable to durum. However, there is a need to broaden the genetic base for resistance in durum wheat. The objective of this work was to introgress resistance from selected Triticum araraticum and T. carthlicum accessions using multiple backcross methodology. The experimental recipient durum wheat included numerous adapted and high‐yielding lines. Testing for Hessian fly resistance under controlled conditions and field yield data showed that this programme yields Hessian fly‐resistant durum lines with good yields and adaptation.
Breeding strategies for early soybeans in Belarus
Authors: Rosenzweig V. E. , Goloenko D. V. , Davydenko O. G. , Shablinskaya O. V. , Swiecicki W.
Published: October 2003

Yield and other agronomic traits in soybean depend on the growth habit. The best maturity group, 00 indeterminate cultivars, compared with semi determinate cultivars for 3 years, out yielded the latter by 9%, possessed greater height and node number but somewhat stronger lodging and better lower bottom pod set. Maturity did not differ significantly within the samples. Correlations were recorded between the yield, growth type and node number. Indeterminate cultivars, in general, require fewer days to start flowering than determinate cultivars. This character is useful in the development of cultivars tolerant to a moderate drought in the second half of the summer. Thus, the most likely model of maturity group 00 variety for Belarus may be an indeterminate, early flowering, full season cultivar.
Improving male fertility restoration of common wheat for Triticum timopheevii cytoplasm
Authors: Chen Q.‐F. , Wehling P.
Published: October 2003

The fertile pure line R3‐37 of common wheat with cytoplasm of Triticum timopheevii Zhuk. is an R‐line (restorer) that can restore the male fertility of A‐lines (male sterile lines) with T. timopheevii cytoplasm. In breeding hybrid wheat, the hybrid of the cross R3‐37/ Baimian3 was found to be completely male sterile, indicating that Baimian3 has some genes that are epistatic to the Rf genes in R3‐37. In order to elucidate the essence of this phenomenon, the male fertilities of the hybrids of 27 crosses including R3‐37 and/or Baimian3 were studied. The results show that inheritance of male fertility of the hybrid R3‐37/Baimian3 involves interactions among Rf alleles, male fertility‐inhibiting genes and genetic background. Although more than 70 different kinds of male sterile cytoplasm to common wheat have been discovered, the systems of hybrid wheat production based on male sterile cytoplasm are all the A‐line/R‐line type and all have similar problems of hybrid fertility restoration. This study confirmed that there is a new model (A‐line/R*‐line//R‐line) for producing hybrid wheat with high fertility restoration. In the new model, the completely male sterile hybrids of A‐line/R*‐line can act as common A‐line.
Screening Cucumis sativus landraces for resistance to cucumber vein yellowing virus
Authors: Picó B. , Villar C. , Nuez F. , Weber W. E.
Published: October 2003

Cucumber production in Spain is being threatened by the cucumber vein yellowing virus (CVYV), which has been causing severe yield losses since it was first detected in 2000. Although most of the Spanish cucumber production is based on hybrid cultivars, farmers have grown cucumber landraces for centuries. A collection of 46 Spanish cucumber landraces, four melon cultivars and one accession of Cucumis africanus, were evaluated for resistance to CVYV. An isolate of CVYV from Almeria, closely related to CVYV from Israel, was used. CVYV was mechanically transmitted and detected by reverse transcriptase polymerase chain reaction and molecular hybridization. Only mild infections were observed in melons, while the wild species C. africanus was susceptible to this disease. Most of the cucumber accessions assayed were highly susceptible to CVYV and showed vein‐clearing symptoms, severe growth reduction and a high viral accumulation. Several cucumber accessions were partially resistant to this virus, displaying mild symptoms and a significantly reduced viral accumulation. These partially resistant varieties could be cultivated under integrated production systems, and also be used as resistance sources to develop new cucumber hybrids resistant to CVYV.
In vitro quantification of barley reaction to leaf stripe
Authors: Arabi M. I. E. , Jawhar M. , Friedt W.
Published: October 2003

An in vitro technique was used to quantify the infection level of leaf stripe in barley caused by Pyrenophora graminea. This pathogen penetrates rapidly through subcrown internodes during seed germination of susceptible cultivars. Quantification was based on the percentage of the pieces of subcrown internodes that produced fungal hyphae cultured on potato dextrose agar media. The disease severity was evaluated among five cultivars with different infection levels and numerical values for each cultivar were obtained. A significant correlation coefficient (r = 0.91, P < 0.02) was found among the in vitro and field assessments. In addition, the results were highly correlated (r = 0.94, P < 0.01) among the different in vitro experiments, indicating that this testing procedure is reliable. The method presented facilitates a rapid preselection under uniform conditions which is of importance from a breeder's point of view. Significant differences (P < 0.001) were found for the length of subcrown internodes between inoculated and non‐inoculated plants with leaf stripe. Isolate SY3 was the most effective in reducing the subcrown internode length for all genotypes.
Hybrid seed production in safflower (Carthamus tinctorius) following the induction of male sterility by gibberellic acid
Authors: Baydar H. , Gökmen O. Y. , Friedt W.
Published: October 2003

The objective of the present research was to develop an effective and practical method for hybrid seed production in safflower, by inducing male sterility with gibberellic acid (GA3). Seeds of the spiny line ‘5‐154’ and the non‐spiny variety ‘Dincer 5‐118’ were sown in alternate rows and the plants of the non‐spiny female variety were exposed to various concentrations of GA3 for male sterility induction. Three successive sprays (75, 82 and 89 days after sowing) of 100 p.p.m. of GA3 to safflower buds of <0.5 cm diameter at a pre‐meiotic interphase stage resulted in reduced pollen viability from 81.6‐6.7% compared with the control. An average hybrid seed percentage of 80.7% (87.5% in the secondary heads), identified by the use of the spiny‐capitulum marker variety ‘5‐154′, was obtained. The GA3 treatments did not significantly affect the production of viable achenes. The results showed that GA3 could be successfully used as a chemical hybridizing agent in hybrid safflower production.
Susceptibility to sharka (Plum pox virus) in Prunus mandshurica×P. armeniaca seedlings
Authors: Rubio M. , Dicenta F. , Martínez‐Gómez P. , Weber W. E.
Published: October 2003

Prunus mandshurica [(Maxim.) Koehne] from Central Asia is a species related to apricot and grown in China and Mongolia. This species has been used in apricot breeding as a source of frost resistance. In addition, P. mandshurica has been suggested as the possible origin of some North American apricot cultivars resistant to sharka (Plum pox virus, PPV). The aim of this work was to transmit the resistance to PPV from P. mandshurica to the Spanish apricot cultivar ‘Currot’ by traditional crossing. The resistance to a Dideron PPV isolate of the descendants of P. mandshurica×‘Currot’ and their progenitors was evaluated under controlled conditions in a greenhouse. The results showed the susceptibility of both, the progenitors and the offspring to PPV, as being much higher than in other apricot seedlings. The results showed that the P. mandshurica accession studied is not a good progenitor in breeding apricot for PPV resistance, but just the opposite. The possible role of P. mandshurica as a source of resistance in apricot resistant cultivars is questioned.
Effects of tachykinins and 5‐hydroxytryptamine on intestinal secretion
Authors: Coupar Ian M , Di Iulio Juliana L
Published: October 2003

1. The main aim of the present study was to establish the functional in vivo effects of tachykinins on net fluid transport by the jejunum and ileum of anaesthetized rats. Tachykinins were administered by retrograde infusion in saline into the left common carotid artery. The possible involvement of 5‐hydroxytryptamine (5‐HT) in tachykinin‐induced intestinal secretion was also investigated.

2. Some tachykinins were potent at reversing net absorption to secretion, particularly in the jejunum, where the rank order of potency was neurokinin (NK) A > substance P (SP) > NKB. The potency of the NK1 receptor‐selective agonist [Sar9,Met(O2)11]‐SP was the same as SP. Neurokinin A reduced net fluid absorption from the lumen of the jejunum at an intra‐arterial infusion rate of 0.64 µg/kg per min. Infusions of NKA at 1.6 and 4 µg/kg per min induced net secretion into the lumen of the jejunum. These two higher infusion rates also affected fluid transport by the ileum, although not to the same extent as seen in the jejunum. The relative potency of SP was not affected by captopril (10 mg/kg, i.v.).

3. The secretory response of the jejunum to infusion of 4 µg/kg per min SP was blocked in animals administered the NK1 receptor antagonist SR 140 333 (1 mg/kg, i.v.). In addition, SR 140 333 blocked the secretory response to 4 µg/kg per min NKA. However, NKA still induced secretion in animals that had received the NK2 receptor antagonist SR 48 968 (0.3 mg/kg, i.v.).

4. A role for an endogenous tachykinin in the intestinal secretory action of 5‐HT was not clearly established using the present model. Although SR 140 333 increased the absorption rate from the jejunum in animals infused intra‐arterially with 5‐HT, 5‐HT itself did not cause a significant reduction in absorption. There were no significant differences in the absorption rates from the ileum between the control group and groups infused with 5‐HT with and without SR 140 333.

5. The present study provides functional evidence for the existence of NK1 receptors in the rat small intestine, particularly in the proximal region, where their activation influences fluid transport. It is suggested that the presently used rat model is suitable for screening tachykinin antagonists for potential antidiarrhoeal activity.
Changes in glycated haemoglobin levels in diabetic rats measured with an automatic affinity HPLC
Authors: Nagisa Yasutaka , Kato Koki , Watanabe Kaoru , Murakoshi Hitomi , Odaka Hiroyuki , Yoshikawa Kazuhide , Sugiyama Yasuo
Published: October 2003

1. The level of glycated haemoglobin (GHb) in diabetic rats was measured using a newly developed automatic high‐performance liquid chromatography (HPLC) with a boronate affinity column that requires only 2.5 min per sample for analysis.

2. Levels of GHb were 2.7% in normal 7‐week‐old Sprague‐Dawley rats. These levels increased gradually following the abrupt induction of hyperglycaemia by intravenous injection of streptozotocin (STZ), reaching a maximal level of 10.1% after 6 weeks.

3. Glycosylated haemoglobin (HbA1) levels measured by cation‐exchange chromatography were also increased by STZ treatment, although HbA1 values were lower than GHb measured by affinity column HPLC.

4. In Wistar fatty rats, GHb levels declined gradually over 5 weeks following the administration of pioglitazone (0.75 or 2.25 mg/kg per day) as a food admixture, which reduced plasma glucose (PG) levels to normal levels within 1 week. Glycated haemoglobin levels after 5 weeks treatment with pioglitazone correlated better with the area under the curve for PG over the entire 5 week treatment period than with the PG level at the end of treatment.

5. In addition, GHb determined by affinity column HPLC correlated well with HbA1 measured by cation‐exchange chromatography, although the GHb value was higher than the HbA1 value.

6. Glycated haemoglobin levels in db/db and KKAy mice were higher than those in control normoglycaemic animals and were also higher than HbA1 values measured by the cation‐exchange method, although the two values did show good correlation.

7. These results indicate that the newly developed affinity column HPLC system is useful for evaluating total GHb levels in rats as an index of antidiabetic treatment.
What we don't know about the structure of ryanodine receptor calcium release channels
Authors: Dulhunty Angela F , Pouliquin Pierre
Published: October 2003

1. The ryanodine receptor (RyR) is the Ca2+ release channel in the sarcoplamic reticulum of skeletal and cardiac muscle and is essential for respiration and heart beat. The RyR channel releases Ca2+ from intracellular stores in a variety of other cell types, where it normally coexists with the inositiol 1,4,5‐trisphosphate receptor (IP3R). The RyR and IP3R, forming a superfamily of homotetrameric ligand‐gated intracellular Ca2+ channels, serve discrete functions: they can be located in independent Ca2+ stores with different activation mechanisms and can be coupled to different signalling pathways.

2. Although functional characteristics of the RyR have been investigated intensely, there remain major gaps in our knowledge about the structure of the protein, its ion‐conducting pore, its ligand‐binding sites and sites supporting the many protein/protein interactions that underlie the in vivo function of the channel.

3. Of particular importance are the transmembrane segments that form the membrane‐spanning domain of the protein and the pore, define the conductance and selectivity of the channel and dictate the cytoplasmic and luminal domains and the overall protein structure. Hydropathy profiles predict between four and 12 transmembrane segments. One popular model shows four transmembrane segments in the C‐terminal one‐tenth of the protein. However, there is substantial evidence for a larger number of membrane‐spanning segments located in both the C‐terminal and central parts of the protein.

4. A model of the RyR pore based on the Streptomyces lividans KcsA channel structure is presented. Protein/protein interactions between the RyR and other regulatory proteins, as well as within the RyR subunit, are discussed.
Protective effects of α‐tocopherol and mannitol in both circulatory shock and cerebral ischaemia injury in rat heatstroke
Authors: Niu KC , Lin KC , Yang CY , Lin MT
Published: October 2003

1. There is evidence that hydroxyl radicals are accumulated and oxidative stress is produced in multiple organs, including the brain, of rats with heat stroke. Herein, we investigated the effect on heat stroke‐induced circulatory shock and cerebral ischaemic injury of two free radical scavengers, namely mannitol and α‐tocopherol.

2. Urethane‐anaesthetized rats were exposed to heat stress (ambient temperature 42°C) to induce heat stroke. Control rats were exposed to 24°C. Mean arterial pressure and cerebral blood flow after the onset of heat stroke were significantly lower in heat stroke rats than in control rats. However, cerebral free radicals, lipid peroxidation and the neuronal damage score were greater in heat stroke rats compared with control rats. Similarly, plasma cytokines, including tumour necrosis factor‐α, interleukin (IL)‐1β and IL‐6, were significantly higher in heat stroke rats compared with their normothermic controls.

3. Pretreatment with α‐tocopherol (20 mg/kg, i.v.) or mannitol (10%, i.v.) 30 min before the onset of heat exposure significantly attenuated heat stroke‐induced arterial hypotension, cerebral ischaemia and neuronal damage, the increased free radical formation and lipid peroxidation in the brain and the increased plasma levels of cytokines. Pretreatment with α‐tocopherol or mannitol resulted in a prolongation of survival time in heat stroke.

4. These results demonstrate that although pretreatment with α‐tocopherol and mannitol does not prevent the heat stroke syndrome entirely, an attenuation of the syndrome is observed.
Effect of oral ketorolac and gender on human cold pressor pain tolerance
Authors: Compton Peggy , Charuvastra VC , Ling Walter
Published: October 2003

1. Although the analgesic effect of opioids on experimental cold pressor (CP) pain has been well demonstrated, the analgesic effect of non‐steroidal anti‐inflammatory drugs (NSAIDs) on experimental CP pain has been less reliable, a finding complicated by inconsistencies in how CP analgesic effect is measured.

2. In the present study, a clinically relevant CP response of pain tolerance was used to assess the previously undescribed analgesic efficacy of the potent NSAID ketorolac (10 mg, p.o.), on CP pain across gender in a sample of normal subjects (n = 50).

3. Using a placebo‐controlled crossover design, neither a main nor interaction effect for ketorolac on CP pain tolerance was detected. When examined by gender, male subjects exhibited a large placebo response to CP pain under study conditions, whereas women (albeit less pain tolerant at baseline) evidenced no placebo effect but a modest‐to‐good NSAID analgesic response.

4. Findings on the gender‐specific placebo and analgesic NSAID response, integrated with the current literature, indicate that the lack of NSAID analgesic efficacy in the CP pain model may be related to unexamined and differential effects of how gender affects NSAID analgesic effect.
Regulation of axonal growth and guidance by the neurotrophin family of neurotrophic factors
Authors: Gillespie Lisa N
Published: October 2003

1. The neurotrophins play an important role during development to stimulate and guide axonal growth for the establishment of a correctly wired and functional neural system. Neurotrophins can also regulate adult nervous system plasticity by promoting neuronal survival and stimulating nerve regrowth following injury.

2. Therefore, the potential exists for these neurotrophic factors to be used as therapeutic agents for the treatment of neurodegenerative disorders. However, in order to realize the full capacity of neurotrophic factors as therapeutic agents, it is important to understand the mechanisms by which they elicit their survival and regenerative effects.

3. The present paper reviews some of the ways in which neurotrophins regulate axonal growth and guidance.
Investigation of the effects of peppermint oil and valerian on rat liver and cultured human liver cells
Authors: Vo Liem T , Chan David , King Roger G
Published: October 2003

1. The aim of the present study was to investigate the effects of peppermint oil and valerian on rat liver and cultured human hepatoma cells.

2. Rats received a single oral dose of peppermint oil (8.3–830 µL/kg) or valerian (0.31–18.6 g/kg), or daily oral doses of 83 µL/kg peppermint oil or 3.1 g/kg valerian for 28 days. After 24 h, rats were anaesthetized and measurements made of bile flow, liver function and in vivo sinusoidal area. Livers were then removed for histology.

3. Bile flow was unaffected by any treatment, except acute high‐dose peppermint oil (830 µL/kg; 70% increase in flow). No change in liver enzyme activity was found, except for a 45% increase in alkaline phosphatase after chronic peppermint oil. No change in sinusoidal area in vivo or in histology was found following any treatment, although pretreatment with carbon tetrachloride reduced sinusoidal bed area and produced histological damage. Incubation of human hepatoma cells with 0.5 µL/mL (but not 0.05 µL/mL) peppermint oil or 20 mg/mL (but not 2 mg/mL) valerian resulted in increased cell death.

4. In conclusion, the present study demonstrated in vitro toxicity of high doses of valerian and peppermint oil in cultured human hepatoma cells and, at doses 2–3 orders of magnitude greater than those recommended for human use, an increase in rat bile flow after acute peppermint oil and an increase in alkaline phosphatase after chronic peppermint oil.
Effect of tetramethylpyrazine on potassium channels to lower calcium concentration in cultured aortic smooth muscle cells
Authors: Wong Kar‐Lok , Chan Paul , Huang Wei‐Chan , Yang Tzyy‐Lin , Liu I‐Min , Lai Tung‐Yuan , Tsai Chin‐Chuan , Cheng Juei‐Tang
Published: October 2003

1. Tetramethylpyrazine (TMP) is one of the active principles contained in Ligusticum chuanxiong Hort. (Umbelliferae), a herb that has been used widely in China to treat vascular disorders.

2. In an attempt to elucidate the possible mechanisms of action of TMP, the effect of TMP on intracellular calcium concentrations ([Ca2+]i) was investigated in cultured vascular smooth muscle (A7r5) cells using the Ca2+‐sensitive dye Fura‐2 as an indicator.

3. The increase in [Ca2+]i in A7r5 cells produced by vasopressin (1 µmol/L) or phenylephrine (1 µmol/L) was attenuated by TMP in a concentration‐dependent manner. Only inhibitors specific to ATP‐sensitive potassium (KATP) channels or small conductance calcium‐activated potassium (SKCa) channels attenuated the action of TMP (10 µmol/L) on [Ca2+]i. However, blockers of other K+ channels failed to modify the inhibitory action of TMP (10 µmol/L) on [Ca2+]i.

4. The action of TMP on membrane potential in A7r5 cells was monitored by the fluorescence of bisoxonol. Tetramethylpyrazine caused a concentration‐dependent inhibition of changes in membrane potential elicited by KCl (20 mmol/L) or phenylephrine (1 µmol/L), an effect that was totally reversed by glibenclamide (100 µmol/L) and apamin (100 nmol/L) in combination.

5. The results obtained indicate that the decrease in [Ca2+]i in A7r5 cells produced by TMP is mediated mainly by opening of KATP and/or SKCa channels.
Diet‐induced obesity and cardiovascular regulation in C57BL/6J mice
Authors: Williams TD , Chambers JB , Roberts LM , Henderson RP , Overton JM
Published: October 2003

1. In the present study, we determined the effect of diet‐induced obesity on cardiovascular and metabolic regulation in mice at standard laboratory temperatures (ambient temperature (Ta) = 22°C) and during exposure to thermoneutrality (Ta = 30°C).

2. Male C57BL/6J (B6) mice fed a high‐fat diet (HFF; n = 17) or chow (CHW; n = 14) for 15 weeks were surgically instrumented with telemetry devices, housed in metabolic chambers and assigned to either control or atenolol treatment (25 mg/kg per day in drinking water) to determine the effects of obesity on baseline cardiovascular function and on the responses to thermoneutrality and 24 h fasting. Mean arterial pressure (MAP), heart rate (HR), arterial pressure and HR variability (time and frequency domain), oxygen consumption (Vo2) and locomotor activity were determined.

3. The HFF mice exhibited increased bodyweight (+10.6 ± 4.1 g), moderate light period hypertension (+8.6 ± 2.6 mmHg), no difference in HR and increased HR variability at standard laboratory temperature compared with CHW controls. Atenolol produced less of a decrease in HR in HFF mice (−42 ± 10 b.p.m.) compared with CHW controls (−73 ± 15 b.p.m.). Acute exposure to thermoneutrality (Ta = 30°C) reduced HR similarly in both HFF and CHW mice (approximately 175 b.p.m.), but reduced MAP less in HFF than in CHW mice (−7.3 ± 2.5 and −15.2 ± 1.0 mmHg), respectively. Atenolol treatment had only minor effects on the HR response to thermonuetrality (−114 ± 13 and −129 ± 8 b.p.m. in HFF and CHW mice, respectively). The HFF mice displayed greater fasting‐induced reductions in light period MAP than did CHW mice (−10.0 ± 1.1 vs−3.1 ± 3.5 mmHg, respectively), whereas HR was decreased equally in both groups. Fasting‐induced increases in HR variability were attenuated in HFF mice.

4. We conclude that diet‐induced obesity produced generally minor changes in cardiovascular regulation in B6 mice at baseline, some of which are distinct from the effects of diet‐induced obesity in larger animal models. In contrast, acute variations in Ta or caloric availability produce pronounced alterations in cardiovascular function in either lean or obese mice, which are generally evident after atenolol and, thus, presumably not due exclusively to variation in cardiac sympathetic activity. Interestingly, the degree of obesity induced hypertension was augmented when mice were studied at thermonuetrality. The results suggest an important unrecognized role for vagal tone in the regulation of cardiovascular function in mice and support the need for considerable caution when using mouse models of obesity to examine regulation of cardiovascular function. We argue that mouse physiology studies should be performed in thermoneutral conditions.
Development of an artificial diet for the western corn rootworm
Authors: Pleau Michael J. , Huesing Joseph E. , Head Graham P. , Feir Dorothy J.
Published: October 2003

The Western Corn Rootworm, Diabrotica virgifera (WCR; Coleoptera: Chrysomelidae), is a serious pest of maize, causing approximately one billion dollars a year in losses and control costs. The insect has become resistant to several chemical controls and growers have asked for a control solution based on genetically‐enhanced resistant varieties. Key to the production of genetically‐enhanced germ plasm is the ability to use artificial diets for bioassays to identify proteins with activity against the target insect. However, artificial diets currently used for WCR bioassay do not support good WCR larval development because they were developed and optimized for the Southern Corn Rootworm (SCR). The present study was conducted to understand the nutritional physiology of WCR by altering the dietary constituents of a SCR diet and measuring the subsequent effects on WCR growth. Alteration of most dietary constituents had surprisingly little effect on WCR larval growth. The most significant factors affecting WCR growth on artificial diet were removal of formalin, addition of plant adjuvant, and adjustment of dietary pH to 9.0. These dietary changes resulted in larval WCR growth rates that were nearly double those in standard SCR rootworm diets. In some cases, WCR larvae fed on the improved diet obtained larval masses approaching those of larvae fed on maize roots.
Immersion survival differs among three Diabrotica species
Authors: Hoback W. Wyatt , Clark Thomas L. , Meinke Lance J. , Higley Leon G. , Scalzitti Joanne M.
Published: October 2003

Soil dwelling invertebrates including insects and their larvae are subjected to severe oxygen limitations when the soil becomes saturated or covered by water. Differential survival of this stress may in part explain ecological range of a species and could lead to cultural control methods for economically important species. We tested immersion survival for larvae of three species of Diabrotica (viz., D. balteata LeConte, D. undecimpunctata undecimpunctata Mannerheim, and D. virgifera virgifera LeConte). Groups of larvae were submersed in conditioned, hypoxic (dissolved oxygen <0.3 ppm) tap water, held at 10, 15, 20, or 25 °C, and periodically removed and assayed for survivorship. We found that time to 50% mortality (LT50) differed significantly between species. Third instar D. u. undecimpunctata were most sensitive to immersion at 25 °C (LT50= 9 h), D. balteata were intermediate (LT50= 15 h) and D. v. virgifera larvae were least sensitive (LT50= 23 h). Second instar D. v. virgifera were significantly more tolerant of immersion than the other species (LT50= 56 hversus 15 h for D. u. undecimpunctata and 11 h for D. balteata). Mortality during immersion corresponds with the build up of lactic acid. Survivorship for all species increased with decreasing temperature. The use of flooding in rootworm management is briefly discussed.
Chemical mediation of differential oviposition and larval survival on rutaceous plants in a swallowtail butterfly, Papilio polytes
Authors: Nakayama Tadanobu , Honda Keiichi , Hayashi Nanao
Published: October 2003

Papilio polytes utilizes only a few plant species of Rutaceae as hosts in the field. We examined in detail the acceptability of Toddalia asiatica (a major host plant) and three other potential rutaceous hosts, Murraya paniculata, Melicope triphylla, and Phellodendron amurense, for ovipositing females of the butterfly. Female responses to the foliage, methanol extracts, and partitioned fractions from these plants were assayed for the presence of oviposition stimulants and/or deterrents. Larval survivorship on these plant species was also compared as an estimate of fitness. The foliage and a methanol extract of T. asiatica readily induced egg‐laying, while females responded moderately to the foliage and a methanol extract of P. amurense. By contrast, ovipositing females only marginally accepted Me. triphylla and completely rejected Mu. paniculata. Further experiments to test the biological activity of fractions derived from the respective plant species revealed that T. asiatica contains potent oviposition stimulant(s) and that weak stimulant(s) are present in P. amurense. Poor or negative oviposition responses to both Me. triphylla and Mu. paniculata proved to be attributable to strong deterrent(s) present in these plants. Larvae performed very well on T. asiatica and P. amurense, whereas larval mortality was much higher on Mu. paniculata and Me. triphylla, suggesting the involvement of antifeedant(s) or toxic substance(s) in these plants.
Dynamic change in photosynthetic pigments and chlorophyll degradation elicited by cereal aphid feeding
Authors: Ni Xinzhi , Quisenberry Sharron S. , Heng‐Moss Tiffany , Markwell John , Higley Leon , Baxendale Frederick , Sarath Gautam , Klucas Robert
Published: October 2003

The concentration of photosynthetic pigments (i.e., chlorophylls a and b, and carotenoids) and chlorophyll degradation enzyme (i.e., chlorophyllase, oxidative bleaching, and Mg‐dechelatase) activities on aphid‐damaged and non‐damaged regions of the infested leaves were determined with two infestation periods (6 and 12 days). Russian wheat aphid [Diuraphis noxia (Mordvilko) (Hemiptera: Aphididae)] feeding caused significant losses of chlorophylls a and b and carotenoids in the damaged regions. However, bird cherry‐oat aphid [Rhopalosiphum padi (L.) (Hemiptera: Aphididae)] feeding did not, except a significantly lower level of carotenoids was observed in the damaged regions from the short‐infestation (6‐day) samples. Interestingly, the non‐damaged regions of D. noxia‐infested leaves on both sampling dates had a significant increase of chlorophylls a and b and carotenoid concentrations when compared with the uninfested leaves. Although D. noxia feeding did not cause any changes in either chlorophyll a/b or chlorophyll (a+b)/carotenoid ratio between the damaged and non‐damaged leaf regions on short‐infestation (6‐day) samples, a significantly lower chlorophyll a/b ratio was detected in long‐infestation (12‐day) samples. The assays of chlorophyllase and oxidative bleaching activities showed no significant differences between the damaged and non‐damaged regions of the infested leaves on either sampling date. Mg‐dechelatase activity, however, was significantly higher in D. noxia‐damaged than non‐damaged leaf regions from the short‐infestation samples, while no differences were detected from the long‐infestation samples. Furthermore, the long‐infestation samples showed that Mg‐dechelatase activity from both D. noxia‐damaged and non‐damaged regions increased significantly in comparison with the respective regions of either uninfested or R. padi‐infested leaves. We infer that non‐damaged regions of D. noxia‐infested leaves compensate for the pigment losses in the damaged regions, and that Mg‐dechelatase activity changed dynamically from a localized response to a systemic response as infestation duration extends. The findings from this study on cereal aphid‐elicited chlorosis (or desistance) would help us to elucidate plant resistance mechanisms, in particular plant tolerance to non‐defoliating herbivory.
The apple sawfly, Hoplocampa testudinea: egg development and forecasting of egg hatch
Authors: Graf B. , Höpli H.U. , Höhn H.
Published: October 2003

The effect of temperature on egg development of the apple sawfly Hoplocampa testudinea Klug was studied under controlled conditions. Based on a linear model describing the relationship between temperature and developmental rates a thermal threshold of 6.9 °C and a thermal constant of 85 day‐degrees were established. The experimental results were used to expand and parameterise an existing phenology model to include egg development and hatching of first instar larvae. The model thus became a valuable forecasting tool not only for adult emergence and the optimal monitoring period but also for egg hatch and the best timing of control measures against first instar larvae. The model was validated by comparing predictions with independent observations on egg‐laying and subsequent hatching of first instar larvae under semi‐field conditions.
Superparasitism in the solitary ectoparasitoid Aptesis nigrocincta: the influence of egg load and host encounter rate
Authors: Babendreier Dirk , Hoffmeister Thomas S.
Published: October 2003

Theory predicts that the acceptance of hosts already parasitized by a conspecific will depend both on egg load and the availability of hosts. In the present laboratory study, we tested the effect of egg load and host encounter rate on the propensity of superparasitism in the solitary parasitoid Aptesis nigrocincta Gravenhorst (Hymenoptera, Ichneumonidae), a synovigeneous ectoparasitoid of prepupae of the European Apple Sawfly. Parasitoid females carry few voluminous eggs at a time and the egg maturation rate is less than one egg per day. Egg load was manipulated by giving females access to hosts one week prior to the start of treatments and host availability by giving females access to either one host cocoon every day or every other day. In the first treatment where females had a high egg load of 5.3 egg in their ovaries and encountered host cocoons at low rates, we found that parasitized hosts were accepted to the same degree as healthy hosts. In females with significantly decreased egg load (3.8 eggs) encountering hosts at the same rate we found a slight but non‐significant decrease in the acceptance of parasitized hosts compared with healthy hosts. In contrast, A. nigrocincta females accepted significantly fewer parasitized hosts at a high host encounter rate that would lead them to the point of egg limitation in the near future. Within the range of egg loads tested, the host encounter rate appears to be the most important determinant for a females decision to oviposit onto hosts already parasitized by a conspecific.