The evolution of recombination in permanent translocation heterozygotes

The evolution of a selectively neutral locus that controls the degree to which alleles at a single selected locus are linked with a particular set of chromosomes in a permanent translocation heterozygote is studied. With complete selfing and fitness overdominance a new allele at the modifying locus will increase in frequency if it increases the linkage of all alleles at the selected locus to a particular set of chromosomes. With random mating a new allele at the modifying locus will increase when rare if it increases the linkage of alleles at the selected locus to a particular set of chromosomes. In addition, a parameter analogous to the coefficient of linkage disequilibrium in usual two-locus models with random mating must be nonzero if a new allele at the modifying locus is to increase in frequency at a geometric rate when rare. With mixed selfing and random mating a new allele at the modifying locus will apparently increase when rare only if it increases the linkage of alleles at the selected locus to a particular set of chromosomes.     

Features of the circadian rhythm of temperature of the skin at children of 8-9 years and young men and girls

Problem of the present work was studying age features circadian rhythm of temperature of a skin with application of a method "Termochron iButton". Day-night rhythm of a skin temperature at two age-grades was investigated: boys and girls of 8-9 years and young men and girls of 20-22 years. For this purpose monitoring temperature during 48 hours with an interval of registration 10 minutes has been lead. Are revealed authentic chronobiological differences: mesor temperatures above at girls, than at boys, and at young men, above, than at girls. Amplitude of a circadian rhythm is above at boys and at girls. Researches chronobiological parameters in the different terms of day have shown, that an average level of temperature at night below at all examinees. The amplitude at adult people in the different terms of day does not differ, while at children it above in the night term.     

Excitation spectra for photosystem I and photosystem II in chloroplasts and the spectral characteristics of the distributions of quanta between the two photosystems.

The parameters listed in the title were determined within the context of a model for the photochemical apparatus of photosynthesis. The fluorescence of variable yield at 750 nm at -196 degrees C is due to energy transfer from Photosystem II to Photosystem I. Fluorescence excitation spectra were measured at -196 degrees C at the minimum, FO, level and the maximum, FM, level of the emission at 750 nm. The difference spectrum, FM-FO, which represents the excitation spectrum for FV is presented as a pure Photosystem II excitation spectrum. This spectrum shows a maximum at 677 nm, attributable to the antenna chlorophyll a of Photosystem II units, with a shoulder at 670 nm and a smaller maximum at 650 nm, presumably due to chlorophyll a and chlorophyll b of the light-harvesting chlorophyll complex. Fluoresence at the FO level at 750 nm can be considered in two parts; one part due to the fraction of absorbed quanta, alpha, which excites Photosystem I more-or-less directly and another part due to energy transfer from Photosystem II to Photosystem I. The latter contribution can be estimated from the ratio of FO/FV measured at 692 nm and the extent of FV at 750 nm. According to this procedure the excitation spectrum of Photosystem I at -196 degrees C was determined by subtracting 1/3 of the excitation spectrum of FV at 750 nm from the excitation spectrum of FO at 750 nm. The spectrum shows a relatively sharp maximum at 681 nm due to the antenna chlorophyll a of Photosystem I units with probably some energy transfer from the light-harvesting chlorophyll complex. The wavelength dependence of alpha was determined from fluorescence measurements at 692 and 750 nm at -196 degrees C. Alpha is constant to within a few percent from 400 to 680 nm, the maximum deviation being at 515 nm where alpha shows a broad maximum increasing from 0.30 to 0.34. At wavelengths between 680 and 700 nm, alpha increases to unity as Photosystem I becomes the dominant absorber in the photochemical apparatus.     

Dyes as fungal inhibitors: effect on colony diameter.

The effects of a wide range of concentrations of 13 dyes on the colony diameters of nine fungal strains (including members of the Deuteromycetes and Zygomycetes) were evaluated. Auramine at a concentration of 50 ppm (50 micrograms/ml), methylene blue at a concentration of 500 ppm, gentian violet at a concentration of 5 ppm, and phenol red at a concentration of 50 ppm performed as well as the commonly used dyes dichloran at a concentration of 2 ppm and rose bengal at a concentration of 50 ppm in that they allowed adequate colony development of the Deuteromycetes strains tested and controlled rapidly spreading fungi.     

Saturated fat feeding, hyperlipidemia and hyperinsulinemia

The effects of feeding saturated and eucaloric unsaturated fat-rich diets on lipemia and insulinemia in female Brown Norway rats have been compared. The relative hyperlipemia in the unsaturated fat group at 8 a.m. has declined at 10 a.m., whereas the saturated fat group at 8 a.m. gives lower values than at 10 a.m. It suggests that saturated fat feeding requires a longer absorption period. The insulin levels in the unsaturated fat groups are higher at 8 a.m. than at 10 a.m., whereas insulin levels in the saturated fat group are higher at 10 a.m. than at 8 a.m. It also suggests retarded resorption of food in the saturated fat group. The relative hyperlipemia at 10 a.m. in the saturated fat group applies to triacylglycerol, free cholesterol, free fatty acids and particularly phosphatidylcholine. It was almost 50% higher than phosphatidylcholine in the unsaturated fat group and coincided with the accumulation of an apolipoprotein E-rich high density lipoprotein.     

Casual Attendances at an Accident Department and a Health Centre

In six months patients from a defined population of 11,417 provided 826 casual attendances for minor conditions at a hospital accident department and 1,430 similar attendances at a health centre treatment room. Attendances at the accident department reached a peak during the early evening, and included relatively more males, more adults, more patients with injuries than with symptoms, and more residents from the area immediately adjoining the hospital.Care of most of the casual attenders with minor conditions at the health centre treatment room would require additional nursing staff and some reorganization of primary care to enable a doctor to be available at most times. Attendances at night and at week-ends were insufficient to justify a 24-hour service at the health centre.     

Kinesin undergoes a 9 S to 6 S conformational transition.

Addition of NaCl or KCl in the presence of 50 nM ATP induces a shift in the sedimentation coefficient (apparent S20,w) of kinesin from 9.4 S at low ionic strength to 6.5 S at high ionic strength. The midpoint for the transition occurs at ionic strength values of 0.39, 0.25, and 0.18 for pH values of 6.3, 6.9, and 8.3, respectively. Gel filtration experiments indicate that the transition to the 6.5 S species is accompanied by a decrease in the diffusion coefficient. Under all conditions which were tested, the 64-kDa beta subunits comigrate with the 120-kDa alpha subunits without any evidence for dissociation of the alpha 2 beta 2 complex. These results are consistent with the change in sedimentation coefficient being due to a conformational transition between a folded form at low ionic strength and an extended form at high ionic strength. This conformational transition is not significantly affected by the nature of the nucleotide bound at the active site since similar results are obtained both in the presence of excess EDTA, which removes the bound ADP, and after replacement of the bound ADP with adenosine 5'-(beta,gamma-imino)triphosphate. The alpha 2 form of kinesin, which lacks the beta subunits, undergoes a similar transition between a 6.7 S form at low ionic strength and a 5.1 S form at high ionic strength with a midpoint for the transition at an ionic strength of 0.5 at pH 6.9. Electron microscopic observation also indicates a transition between a folded conformation at low ionic strength and an extended conformation at high ionic strength for both the alpha 2 beta 2 and alpha 2 species.     

Cyclooxygenases and prostaglandin E synthases in preimplantation mouse embryos

Prostaglandin E2 (PGE2) is shown to be essential for female reproduction. Cyclooxygenase (COX) is a rate-limiting enzyme in prostaglandin synthesis from arachidonic acid and exists in two isoforms: COX-1 and COX-2. Prostaglandin E synthase (PGES) is a terminal prostanoid synthase and can catalyse the isomerization of the COX product PGH2 to PGE2, including microsomal PGES-1 (mPGES-1), cytosolic PGES (cPGES) and mPGES-2. This study examined the protein expression of COX-1, COX-2, mPGES-1, cPGES and mPGES-2 in preimplantation mouse embryos by immunohistochemistry. Embryos at different stages collected from oviducts or uteri were transferred into a flushed oviduct of non-pregnant mice. The oviducts containing embryos were paraffin-embedded and processed for immunostaining. COX-1 immunostaining was at a basal level in zygotes and a low level at the 2-cell stage, reaching a high level from the 4-cell to blastocyst stage. COX-2 immunostaining was at a low level at the zygote stage and was maintained at a high level from the 2-cell to blastocyst stages. A low level of mPGES-1 immunostaining was observed from the zygote to 8-cell stages. The signal for mPGES-1 immunostaining became stronger at the morula stage and was strongly seen at the blastocyst stage. cPGES immunostaining was strongly observed in zygotes, 2-cell and 8-cell embryos. There was a slight decrease in cPGES immunostaining at the 4-cell, morula and blastocyst stages. mPGES-2 immunostaining was at a low level from the zygote to morula stages and at a high level at the blastocyst stage. We found that the COX-1, COX-2, mPGES-1, cPGES and mPGES-2 protein signals were all at a high level at the blastocyst stage. PGE2 produced during the preimplantation development may play roles during embryo transport and implantation.     

Effects of step changes in pH on isometric tetanic tension of toad sartorius muscle

The effect of a rapid change in pHe (pH of bathing solution) on the isometric tetanic tension developed by sartorius muscles of toads acclimated to 5 and 25 degrees C was measured at 5 and 25 degrees C. The pH was altered by changing the carbon dioxide concentration of a bicarbonate buffered physiological solution. Acclimation temperature did not modify the response to a rapid change in pH, but test temperature did. Following a pH decrease from 9.0 to 6.0, tetanic tension decreased at a faster rate at 5 degrees C than at 25 degrees C. A new steady state was reached in 15 min at 5 degrees C but in 40 min at 25 degrees C. Following a pH increase from 6.0 to 8.5, tetanic tension increased at a faster rate at 25 degrees C than at 5 degrees C. A new steady state was reached in 60 min at 5 degrees C but in 10 min at 25 degrees C. We conclude that the rate of carbon dioxide diffusion through the sartorius muscle is only one factor that determines how rapidly tetanic tension changes following the step change in pH, and that muscle resists pH change more effectively at higher temperatures.     

Physical characteristics of hyaluronate binding to the surface of simian virus 40-transformed 3T3 cells

The binding of labeled hyaluronate to the surface of Simian virus 40-transformed 3T3 cells was studied as a function of 1) pH, 2) ionic strength, 3) temperature, and 4) molecular weight of the hyaluronate. Binding occurred over a wide range of pH values with optima at pH 7 and at less than pH 4. Binding at low pH was eliminated at high ionic strength whereas that at physiological pH was enhanced, with a maximum at 0.5 M NaCl. The enhancement of binding at pH 7 was reversible and independent of the particular salt used. Scatchard plot analysis showed that increasing the ionic strength resulted in both a decrease in the dissociation constant (Kd) and an increase in the amount bound at saturation (Bmax). Temperature also influenced the binding of hyaluronate to the cell surface. The amount bound at low temperatures (0 degrees C) was 3 to 5 times that bound at high temperatures (40 degrees C) with a sharp transition occurring at 18 degrees C, the temperature of phase transition of the plasma membrane. The temperature effect was primarily a change in the Bmax and was reversible. Finally the molecular weight of the ligand influenced the binding. High molecular weight preparations of hyaluronate had a higher binding affinity (lower Kd) and a lower Bmax than did smaller molecular weight preparations.     

Characterization and evaluation of Aspergillus oryzae lactase coupled to a regenerable support

A derivative of crosslinked Sepharose, p-(N-acetyl-L-tyrosine azo) benzamidoethyl-CL-Sepharose 4B, was synthesized and used for the selective immobilization of thermostable lactase from Aspergillus oryzae.Preparations of soluble and immobilized lactase were evaluated under initial velocity conditions in a batch process. Immobilization had no significant effect on the pH optimum at 50 degrees C or kinetic parameters at pH 4.5 or pH 6.5 and 50 degrees C. At pH 4.5, the soluble enzyme possessed maximum activity at 60 degrees C and the immobilized at 55 degrees C; at pH 6.5 both showed maximum activity at 55 degrees C. The activation energy, entropy, and enthalpy decreased significantly with immobilization at pH 4.5 but not at pH 6.5. When the immobilized enzyme was placed in a packed-bed reactor, the effect of temperature on activity was altered as reflected by a marked decrease in the thermodynamic parameters of activation at both pH levels. Upon immobilization there was also a dramatic increase in the apparent thermal stability of the lactase, and the mean half-life at 50 degrees C was increased from 7.2 to 13 days at pH 4.5 and from 3.8 to 16 days at pH 6.5.     

Role of mechanosensitivity of the endothelium in weakening of the vascular bed vasoconstriction

The effect of control of arterial diameter by the shear stress at the endothelium on noradrenaline-induced constriction of femoral vascular bed was investigated in anaesthetised cats. We compared noradrenaline-induced responses during the perfusion of the hindlimb at a constant blood flow and at a constant pressure as vasoconstriction is accompanied by an increase in wall shear stress only in the former case. We found that the same concentration of noradrenaline at a constant flow caused an augmentation of vascular resistance that was considerably smaller than at a constant pressure perfusion. This difference was almost eliminated after either removal of the endothelium or selective impairment of the endothelial sensitivity to the shear stress. These findings demonstrate that the control of arterial smooth muscle tone at a constant blood flow by shear stress at the endothelium does weaken noradrenaline-induced vasoconstriction.     

Synthesis of macromolecules by Escherichia coli near the minimal temperature for growth

When a culture of Escherichia coli ML30 growing exponentially at 37 C in a glucose minimal medium was shifted abruptly to 10 C, growth decreased for about 4.5 hr. There was no net synthesis of deoxyribonucleic acid (DNA), ribonucleic acid (RNA), and protein. The cells, however, respired at a rate characteristic of cells growing in the steady state at 10 C and were able to accumulate alpha-methyl-d-glucoside. When growth recommenced at 10 C, protein synthesis started at 4 hr, RNA synthesis, with a burst at 6 hr, and DNA synthesis, with a burst at 7 hr. One synchronous division occurred at about 11 hr after shifting to 10 C. There was no alteration in the steady-state RNA to protein ratio. The results are discussed in relation to other reported effects of shifts in environmental conditions. The lag at 10 C was dependent on prior conditions of growth at 37 C. Growth at 37 C under conditions giving catabolite repression were necessary for the lag to be established on shifting to 10 C.     

Rapid biphasic arteriolar dilations induced by skeletal muscle contraction are dependent on stimulation characteristics

To test the hypothesis that measurable changes in microvasculature dilation occur in response to a single short-duration tetanic contraction, we contracted three to five skeletal muscle fibres of the hamster cremaster muscle microvascular preparation (in situ) and evaluated the response of an arteriole overlapping the active muscle fibres. Arteriolar diameter (baseline diameter = 16.4 +/- 0.9 micro m, maximum diameter = 34.7 +/- 1.2 micro m) was measured before and after a single contraction resulting from a range of stimulus frequencies (4, 10, 20, 30, 40, 60, and 80 Hz) within a 250- or 500-ms train. Four and 10 Hz produced a significant dilation at 2.9 +/- 0.4 and 6.5 +/- 2.8 s, respectively, within a 250-ms train and 3.0 +/- 0.2 and 6.1 +/- 1.3 s, respectively, within a 500-ms train. Biphasic dilations were observed within a 250-ms train at 20 Hz (at 3.9 +/- 0.9 and 22.1 +/- 4.3 s), 30 Hz (at 2.7 +/- 0.3 and 17.5 +/- 2.9 s), and 40 Hz (at 3.8 +/- 0.4 and 23.2 +/- 2.6 s) and within a 500-ms train at 20 Hz (at 4.8 +/- 0.4 and 31.9 +/- 3.8 s) and 30 Hz (at 3.4 +/- 0.3 and 27.6 +/- 3.0 s). A single dilation was observed within a 250-ms train at 60 Hz (at 5.1 +/- 0.7 s) and 80 Hz (at 14.2 +/- 3.3 s) and within a 500-ms train at 40 Hz (at 9.9 +/- 3.2 s), 60 Hz (at 7.9 +/- 2.1 s), and 80 Hz (at 13.4 +/- 4.0 s). We have shown that a single contraction ranging from a single twitch (4 Hz, 250 ms) to fused tetanic contractions produces significant arteriolar dilations and that the pattern of dilation is dependent on the stimulus frequency and train duration.     

Fasciola hepatica: motility response to fasciolicides in vitro

The effects of a wide range of fasciolicides on the in vitro motility of Fasciola hepatica have been determined by means of an isometric transducer system. Carbon tetrachloride and diamphenethide do not affect movement at concentrations up to 500 and 100 micrograms/ml, respectively; at 1000 micrograms/ml, however, carbon tetrachloride induces a rapid tonic paralysis. Brotianide and the deacetylated metabolite of diamphenethide cause a rapid flaccid paralysis of the fluke at concentrations of 1.0 micrograms/ml and above. In contrast, the effect of MK-401 is a long-term one, a flaccid paralysis occurring after 20 hr only at 200 micrograms/ml. Praziquantel also produces a flaccid paralysis of the fluke, but this follows an initial increase, then decrease in muscle tone. The effect is rapid at 500 micrograms/ml, but long-term at 100 and 200 micrograms/ml; at these lower concentrations there is also a stimulation of activity. Oxyclozanide , rafoxanide, niclofolan , bithionol, and hexacholorophene induce a rapid spastic paralysis of the fluke at concentrations of 1.0 micrograms/ml and above. Both phasic and tonic components are evident in the response at concentrations of 1.0 micrograms/ml and below; the phasic component disappears at higher concentrations. Nitroxynil produces a similar effect, evident at higher concentrations. Among the benzimidazoles, mebendazole, oxfendazole, and albendazole sulphoxide cause a suppression of motility, whilst thiabendazole and albendazole produce a stimulation of movement. The effects are not rapid, however, for only mebendazole at 500 micrograms/ml causes total inactivity of the fluke within a 12-hr period. Possible explanations for these effects on fluke motility are discussed.     

Clutch and egg size of Tree Swallows along an elevational gradient

How avian reproductive behavior changes at high elevations, and whether changes are the result of adaptation or constraint remains unclear. We compared clutch and egg sizes in two populations of Tree Swallows (Tachycineta bicolor), one at an elevation of ~2500 m a.s.l. in Wyoming's Bighorn Mountains and the other at ~1350 m at the base of these mountains. Females at the high‐elevation site began laying 10 d later, on average, than females at the lower site. Females at the high site laid an average of 0.4 fewer eggs than those at the low site, a significant difference. Eggs were also slightly (2.3%), but significantly, smaller at the high site. Smaller clutches and eggs at the high site may have resulted in part from greater energetic constraints on females. Females at this site faced colder, windier weather during egg formation which would have increased thermoregulatory costs while simultaneously reducing the abundance of prey, i.e., flying insects. Laying a relatively small clutch at the high‐elevation site may also be adaptive, however. Having a smaller brood could help ensure there is an adequate supply of food for each offspring during bouts of inclement weather that are more severe at higher elevations. Also, if the delay in breeding inherent at high elevations reduces the survival prospects of the young, then producing fewer young could enhance a female's chances of breeding again, perhaps at a different location.     

A fifty-year reconstruction of annual changes in the spatial distribution of Pinus banksiana stands: does pattern fit competition theory?

We used tree-ring reconstruction data to study changes in the spatial pattern of live and dead trees at an annual resolution over a 50-year period at four unmanaged, even-aged fire origin jack pine (Pinus banksiana Lamb.) stands in Saskatchewan and Manitoba, Canada. Previous studies of the spatial pattern in P. banksiana have either looked at only a snapshot from a survey done at a single point in time, or repeated measurements of permanent plots taken at 10-year intervals. With annual data, we could examine detailed changes in spatial patterns and relate these to events during stand development and external disturbances. Trees were initially clustered at all sites, but at different distances at each site, most likely because of variability in seedbed distribution at stand initiation. Clustering disappeared over time at all sites, and at a similar mean tree spacing at each site. However, significant regularity only appeared sporadically at one site, indicating that competition with neighbours was not the only factor influencing changes in spatial pattern. At two of the four sites, clustering disappeared suddenly at the same time that mortality rate reached a peak, in one case also coinciding with a jack pine budworm (Choristoneura pinus pinus Freeman) defoliation event. Dead trees were also initially more clustered than the distribution of all trees, but at different distances than the clustering of live trees. This also disappeared over time so that dead trees were eventually a random sample from the distribution of all trees. After the peak of mortality had passed, factors other than competition were determining the dynamics of these forests.     

Inactivation of single cardiac Na+ channels in three different gating modes.

In small cell-attached patches containing one and only one Na+ channel, inactivation was studied in three different gating modes, namely, the fast-inactivating F mode and the more slowly inactivating S mode and P mode with similar inactivation kinetics. In each of these modes, ensemble-averaged currents could be fitted with a Hodgkin-Huxley-type model with a single exponential for inactivation (tauh). tauh declined from 1.0 ms at -60 mV to 0.1 ms at 0 mV in the F mode, from 4.6 ms at -40 mV to 1.1 ms at 0 mV in the S mode, and from 4.5 ms at -40 mV to 0.8 ms at +20 mV in the P mode, respectively. The probability of non-empty traces (net), the mean number of openings per non-empty trace (op/tr), and the mean open probability per trace (popen) were evaluated at 4-ms test pulses. net inclined from 30% at -60 mV to 63% at 0 mV in the F mode, from 4% at -90 mV to 90% at 0 mV in the S mode, and from 2% at -60 mV to 79% at +20 mV in the P mode. op/tr declined from 1.4 at -60 mV to 1.1 at 0 mV in the F mode, from 4.0 at -60 mV to 1.2 at 0 mV in the S mode, and from 2.9 at -40 mV to 1.6 at +20 mV in the P mode. popen was bell-shaped with a maximum of 5% at -30 mV in the F mode, 48% at -50 mV in the S mode, and 16% at 0 mV in the P mode. It is concluded that 1) a switch between F and S modes may reflect a functional change of inactivation, 2) a switch between S and P modes may reflect a functional change of activation, 3) tauh is mainly determined by the latency until the first channel opening in the F mode and by the number of reopenings in the S and P modes, 4) at least in the S and P modes, inactivation is independent of pore opening, and 5) in the S mode, mainly open channels inactivate, and in the P mode, mainly closed channels inactivate.     

Productivity of Thai Brahman and Simmental-Brahman crossbred (Kabinburi) cattle in central Thailand

The productivity of the new crossbred cattle Kabinburi (K) was compared to that of Thai Brahman (TB) using 756 production records from K cattle and 1,316 production records from TB cattle kept at three locations in Thailand. The data were analyzed for the effect of breeds and locations. The ambient temperature, the humidity, the Temperature–Humidity Index (THI) and the rainfall of the three locations were different. Lamphayaklang Livestock Research and Breeding Center (LP) had the highest rainfall/year followed by Nongkwang Livestock Research and Breeding Center (NK), and Prachinburi Livestock Breeding Station (PC). Kabinburi cattle had a higher bodyweight at birth as well as at 200, 400 and 600 days of age than TB cattle. Furthermore, K heifers gave birth to their first calf at a younger age and had a shorter calving interval than TB cows. Thai Brahman cattle kept at LP had significantly higher bodyweight at 400 and 600 days than the animals kept at NK, but bodyweight at birth and 600 days of age were not significantly different. Thai Brahman cattle kept at LP were younger at first calving and had a shorter calving interval than the animals kept at NK. K cattle kept at NK were heavier at birth and at 200, 400 and 600 days of age than the animals kept at PC. Furthermore, Kabinburi cows kept at NK were younger at first calving (P < 0.01), but the calving interval was not different between the two groups kept at NK or PC.     

Effects of the Mitotic Cell-Cycle Mutation cdc4 on Yeast Meiosis

The mitotic cell-cycle mutation cdc4 has been reported to block the initiation of nuclear DNA replication and the separation of spindle plaques after their replication. Meiosis in cdc4/cdc4 diploids is normal at the permissive temperature (25 degrees) and is arrested at the first division (one-nucleus stage) at the restrictive temperature (34 degrees or 36 degrees). Arrested cells at 34 degrees show a high degree of commitment to recombination (at least 50% of the controls) but no haploidization, while cells arrested at 36 degrees are not committed to recombination. Meiotic cells arrested at 34 degrees show a delayed and reduced synthesis of DNA (at most 40% of the control), at least half of which is probably mitochondrial. It is suggested that recombination commitment does not depend on the completion of nuclear premeiotic DNA replication in sporulation medium.--Transfer of cdc4/cdc4 cells to the restrictive temperature at the onset of sporulation produces a uniform phenotype of arrest at a 1-nucleus morphology. On the other hand, shifts of the meiotic cells to the restrictive temperature at later times produce two additional phenotypes of arrest, thus suggesting that the function of cdc4 is required at several points in meiosis (at least at three different times).