The comparison of intrinsic rates of increase among chromosome-substituted lines resistant and susceptible to organophosphate insecticides in Drosophila melanogaster

To investigate the genetic basis of the seasonal fluctuations in resistance to three organophosphates, observed within a natural population of Drosophila melanogaster (Meigen), we compared the intrinsic rate of increase, generation time and net reproduction rate among chromosome substitution lines derived from a resistant and a susceptible line, obtained from this natural population. There was significant variation among substituted lines; lines possessing the third chromosome from the resistant line, which confers resistance to the three organophosphates, generally showed lower mean values of these fitness measures. Chromosomal analyses also indicated significant negative contributions of the third chromosome from the resistant line. However, significant positive contributions of the interactions among chromosomes from the resistant line to these fitness measures were also detected. We further conducted a local stability analysis, in which each chromosome-substituted line was assumed to be introduced at a low frequency into the initial susceptible population. It was demonstrated that the resistance factor(s) on the third chromosome tend to decrease in their frequency under both density-independent and juvenile density-regulated conditions. Based on these results, a possible explanation for the seasonal fluctuations in resistance to the three organophosphates observed in the natural population was proposed.     

Approximation equation for oxygen uptake kinetics in decrement-load exercise starting from low exercise intensity

The purpose of the present study was to determine the degree of fitting an approximation equation for oxygen uptake (Vo(2)) in decrement-load exercise (DLE). Work rate was started from 120 watts and was decreased by a rate of 15 watts per min. The initial work rate of DLE corresponded to 72+/-10% of the work rate at anaerobic threshold determined in incremental-load exercise (ILE). Vo(2) in DLE increased rapidly, reached a peak, and decreased linearly until the end of the exercise. Vo(2) in DLE was higher than that in ILE at the same work rate except in the early periods in ILE and DLE. This difference ranged from 300 to 400 ml/min. This difference is a result of repayment of oxygen debt in DLE and from the oxygen deficit induced by the delay of response of Vo(2) in ILE. As work rate in DLE can be obtained by the difference between work rates in constant-load exercise (CLE) and ILE, we postulated that the approximation equation for Vo(2) kinetics in DLE could be expressed by a combination of approximation equations in CLE and in ILE. When time delay was taken into consideration in this equation, the fitting of data obtained by using the equation was better than that of data obtained by using the equation without a parameter of time delay. The degree of fitting ranged from 94 to 98% (r(2)). Thus, it seems that Vo(2) including oxygen debt in DLE can be approximated by the equation used in this study.     

Factors influencing eating ability of old in-patients in a rehabilitation hospital in Japan

Objectives: This study was designed to determine the factors influencing eating ability of old in‐patients in a rehabilitation hospital. Design: Cross‐sectional investigation. Setting: Forty‐six in‐patients in the rehabilitation ward of Hashimoto Hospital in Kagawa Prefecture in Japan were investigated using a multi‐disciplinary approach. Main outcome measures: Age, gender, state of dentition, muscle activity of lip, cheek and tongue, biting force, salivary flow rate per a minute (SFR), masticatory ability for gummy jelly, swallowing ability, texture of meal, independency of walking (Functional Independence Measure=FIM) and ability to communicate. Results: Bivariate analysis for the relationship between surveyed items and masticatory ability (chi‐square test) identified that better masticatory ability for gummy jelly was associated with age (<85 years), gender (male), state of dentition (dentate), SFR (high), activity of lip (good), biting force (high), swallowing ability (good) and activity of communication (high). Among these items, SFR (p=0.001), gender (p=0.004), ability to communicate (p=0.005) and age (p=0.012) were found having an influence on the masticatory ability (logistic regression analysis). On the other hand, age (<85years), gender (male), SFR (high), activity of lip (good), activity of cheek (good), biting force (high), masticatory ability (good) and swallowing ability (good) had a relationship with normal texture of meal. In regression analysis, only two items, activity of lip (p=0.003) and swallowing ability (p=0.024) emerged as factors on texture of meal. Conclusions: Masticatory ability for gummy jelly was influenced by cognitive function and was excluded from the factors on the state of meal. These results suggested the limitation of evaluation using test food, so dentists should observe eating behaviour of in‐patients. In addition, dentists should pay attention to the activity of the lip and swallowing ability as well as dentition and prostheses in the rehabilitation of eating ability. As SFR was the most significant factor on masticatory ability, this emphasizes the necessity of care for dry mouth caused by side effects of multi‐medication     

Breakdown of self-incompatibility in a natural population of Petunia axillaris caused by loss of pollen function

Although Petunia axillaris subsp. axillaris is described as a self-incompatible taxon, some of the natural populations we have identified in Uruguay are composed of both self-incompatible and self-compatible plants. Here, we studied the self-incompatibility (SI) behavior of 50 plants derived from such a mixed population, designated U83, and examined the cause of the breakdown of SI. Thirteen plants were found to be self-incompatible, and the other 37 were found to be self-compatible. A total of 14 S-haplotypes were represented in these 50 plants, including two that we had previously identified from another mixed population, designated U1. All the 37 self-compatible plants carried either an S(C1)- or an S(C2)-haplotype. S(C1)S(C1) and S(C2)S(C2) homozygotes were generated by self-pollination of two of the self-compatible plants, and they were reciprocally crossed with 40 self-incompatible S-homozygotes (S(1)S(1) through S(40)S(40)) generated from plants identified from three mixed populations, including U83. The S(C1)S(C1) homozygote was reciprocally compatible with all the genotypes examined. The S(C2)S(C2) homozygote accepted pollen from all but the S(17)S(17) homozygote (identified from the U1 population), but the S(17)S(17) homozygote accepted pollen from the S(C2)S(C2) homozygote. cDNAs encoding S(C2)- and S(17)-RNases were cloned and sequenced, and their nucleotide sequences were completely identical. Analysis of bud-selfed progeny of heterozygotes carrying S(C1) or S(C2) showed that the SI behavior of S(C1) and S(C2) was identical to that of S(C1) and S(C2) homozygotes, respectively. All these results taken together suggested that the S(C2)-haplotype was a mutant form of the S(17)-haplotype, with the defect lying in the pollen function. The possible nature of the mutation is discussed.     

Polysaccharide-polynucleotide complexes (15): thermal stability of schizophyllan (SPG)/poly(C) triple strands is controllable by alpha-amino acid modification

Schizophyllan (SPG), a beta-1,3-glucan polysaccharide which is known to form macromolecular complexes with certain polynucleotides, was modified by a reductive amination method with alpha-amino acids (Arg, Lys, and Ser). The thermal stability of the complexes as estimated by T(m) was enhanced in SPG-Arg and SPG-Lys conjugates which have pI values higher than the pH of the medium (8.0). The T(m) shift increased with the increase in the percentage of alpha-amino acid introduced and the highest T(m) values attained were 64 degrees C for SPG-Arg conjugate and 62 degrees C for SPG-Lys conjugate, which are higher by 13 and 11 degrees C, respectively, than those of the unmodified SPG+poly(C) complex. In the SPG-Ser conjugate with a pI lower than the medium pH (8.0), the T(m) values decreased with an increase in the percentage of Ser. Formation of the macromolecular complex was no longer detected above 13.2% Ser. The findings indicate that the T(m) values are easily controllable by the type and percentage of the introduced alpha-amino acids. We believe, therefore, that the present conjugates, consisting of naturally originated SPG and alpha-amino acids, provide an important lead for developing nontoxic artificial vectors and to control the affinity with polynucleotides in response to medium pH and temperature.     

Authentic and recombinant bilirubin oxidases are in different resting forms

Myrothecium verrucaria bilirubin oxidase expressed in Aspergillus oryzae is in a resting form different from that of the authentic bilirubin oxidase, but reaches the resting form of the authentic enzyme after one cycle of reduction and reoxidation with dioxygen as shown by the absorption and electron paramagnetic resonance spectra.     

Rapid measurement of phytate in raw soymilk by mid-infrared spectroscopy

The phytate content in soymilk is known to affect tofu curdling. A rapid measurement of phytate from a water extract of soybean (raw soymilk) in an early stage of tofu processing was investigated using mid-infrared spectroscopy (IR) with an ATR accessory. IR absorption of phytate was observed from 1200 cm-1 to 900 cm-1, and saccharide and protein in the extract also had IR absorption in the same region. In order to separate phytate from other components, the phytate was precipitated completely by the addition of calcium under alkaline condition (pH 11.5). The precipitate was dissolved in citrate buffer (pH 6.0) and then used for IR measurement. The absorbance at 1070 cm-1 correlated well with the phytate content of the soymilk. The measurement of phytate in raw soymilk can be done rapidly by FT-IR measurement with an ATR accessory and gives reproducible values, which can be used for the measurement of phytate content in various soybeans for tofu making.