Genetic and light intensity effects on the activity and emigratory behavior of the house fly,Musca domestica (L.)

The emigratory behavior and locomotor activity of yellow-eyed (y/y), wildtype (+/+), and heterozygous (+/y) house flies was examined at 8 fc (86 lx) and 1600 fc (17,223 lx) light intenstities. At 8 fc, emigration rate and activity of the y/y flies was similar to that of the +/+ and +/y flies. However, at 1600 fc, the y/y flies emigrated at twice the rate and showed an activity of about one-third that of the other genotypes. The behavior of the +/+ and +/y flies remained similar regardless of the experimental design or light intensity. The excessive neural stimulation by high-intensity light resulting from reduced shielding pigments led to behavioral modifications in the visual and tactile responses of the y/y flies.This research was supported in part by grants from the CUNY Faculty Research Award Program (No. 1103) and NIH Biomedical Research Support Grant 5-S05-R-07064.     

Components of predation defense behavior in chickens: evidence for endogenous rhythmicity

The manifestation of diurnal periodicity and the extent of its control by the photoperiod was assessed in three predation defense reactions which constitute either components or outcomes of a predator-prey interaction sequence. Two-hundred White Leghorn chicks were reared from hatching for one week in either 24L or 12L and then tested at one of two clock hours previously demonstrated to define peak and trough response for one of the components. Putative evidence was found for an endogenous source of the periodicity manifested in all reactions. Maintenance schedule did not entrain the periodicity, but simple room entry and handling elicited anti-predator reactions, the extent of which varied as a function of clock hour. A general model of predation defense behavior was proposed.     

Associated changes in Ca2+ and Sr2+ activation properties and fiber proteins in cross-reinnervated rabbit soleus

Changes in the Ca²⁺ and Sr²⁺ activation properties of functionally skinned slow-twitch soleus fibers were measured and compared with those of normal fast-twitch extensor digitorum longus (EDL) following cross-reinnervation of soleus with the nerve to EDL. Most of the fibers showed either complete transformation of activation properties (66%) or remained unchanged (34%). The change in sensitivity to divalent cations was correlated with changes in the proteins present in fibers pooled on the basis of their activation properties. The banding patterns of the 35,000- and 37,500-dalton proteins (tropomyosin and troponin T) in cross-reinnervated soleus were correspondingly transformed to those of normal EDL. Slow and fast myosin light chains were present in the pooled cross-reinnervated fibers. Fiber distributions based on activation properties were confirmed by histochemical features. For the first time it has been demonstrated that cross-reinnervation produced changes in the activation properties of soleus fibers and associated changes in the regulatory proteins measured.     

股骨远端骨折两种固定方法对比研究

目的 对比应用逆行交锁髓内钉(GSH)和动力髁螺钉(DCS)内固定治疗股骨远端骨折的效果.方法 采用回顾性研究方法对我院自2000年8月～2004年10月治疗的54例股骨远端骨折病例进行对照研究,按A0分类:A1型17例,A2型14例,A3型11例,B1型2例,C1型6例,C2型3例,C3型1例.其中,DCS内固定30例,GSH固定24例.分组统计手术时间,出血量,骨折愈合时间,并发症,膝关节功能.结果 所有病例经5月～2年随访,平均9个月;骨折愈合时间为4.6月(4～9月).DCS固定组平均手术时间1.5小时(1～2.5小时).出血量105 ml(50～200 ml),骨折愈合时间平均4.7月(4～8月),并发症发生5例(发生率16.7%),根据Kolmert膝关节功能评分,优20例,良6例,可4例,优良率为86.6%.GSH固定组手术时间1.8小时(1.5～3.5小时).术中出血量平均120 ml(100～250 ml),平均骨折愈合时间5.1个月(4.5～9个月),并发症发生5例(发生率28%),根据Kolmert膝关节功能评分标准,优15例,良7例,可2例,优良率为91.7%.两组比较,结果无显著差异(P＞0.05) 结论 逆行带锁髓内钉(GSH)及动力髁螺钉(DCS)均是治疗股骨远端骨折的较好方法,但各有其最佳适应症.选择好适应症以及术者技术熟练有利于骨折愈合及关节功能恢复.     

Quantitative trait loci (QTL) for circadian rhythms of locomotor activity in mice

The loomotor activity of male mice (Mus musculus) was monitored by infrared photoelectric beams under three lighting regimens: LD (12 h of light and 12 h of dark), DD (constant dark), and LL (constant broad-spectrum light, 10 lux). Circadian period of locomotor activioty (τ) was compared among 3 inbred strains of mice, C57BL/6J (B6), BALB/c (C), and DBA/2J (D2), and 26 recombinant inbred strains B×D (B6×D2). the τ under both continuous low-intensity light and continuous darkenss varied significantly among strains. Under DD the mean τ was 23.8 h for B6, 23.7 h for D2, and 23.6 h for C. Under LL the mean τ was 25.1 for B6, 23.9 h for D2, and 25.5 h for C. Frequency histograms of the mean τ of 26B×D RI mouse strains (three to seven animals per strain) in either DD or LL and the difference between them, Δτ, had distributions which appeared unimodal, suggesting polygenic inheritances. The narrow-sense heritability determined using 26 strains of B×D RI mice was about 55% for τ and about 38% for both τ in LL and Δτ. An estimated four loci contribute to the variance of τ in constant darkness and five to the variance of τ in constant low-intensity light among the strains studied. Quantitative trait locus (QTL) analysis identified several potential genetic loci associated with τ in constant darkness, τ in constant low-intensity light, and Δτ. The associations of highest probability for each of these traits were theD1Nds4 locus (p<0.001) on mouse chromosome 1, theD5Ncvs52 locus (p<.05) on mouse chromosome 5, and thePmv12 locus (p<.01) at 70 cM on mouse chromosome 5, respectively. A QTL identified for τ was associated (p<.05) with theD2NDS1 marker at 45 cM on chromsome 2 near the Ea 6 marker at 46 cM associated (p<.05) with that reported for the period of wheel running activity in seven C×B RI strains (Schwartz, W. J., and Zimmerman, P.,J. Neurosci. 10:3685 1990).     

A calmodulin-binding peptide relaxes skinned muscle from guinea-pig taenia coli

During smooth muscle activation the calcium calmodulin complex interacts with myosin light chain kinase (MLCK) whereby activating it. A synthetic peptide analogue (RS20) corresponding to the calmodulin recognition sequence of MLCK has been synthesized and previously found to inhibit the calmodulin stimulated light chain kinase activity. Here we studied the effect of this peptide on skinned fibers from guinea pig taenia coli. Maximal contractions induced by 30 M Ca²⁺ at 0.1 M calmodulin could be completely relaxed by the peptide at 1 M. The inhibitory effect was accompanied by partial dephosphorylation only of the regulatory myosin light chain. Relaxation could be reversed by addition of calmodulin which also increased the extent of light chain phosphorylation.The calmodulin concentration required for reversing the inhibition depended on the concentration of the inhibitory peptide suggesting that the peptide competed with MLCK for the calmodulin binding site. As the calcium-calmodulin-peptide mixture constitutes a calmodulin buffer, our results suggest, that the peptide is a calmodulin antagonist unique in terms of its potency and that less than nanomolar concentrations of free calmodulin may be required for inducing smooth muscle contractions.     

Neutral Polymeric Surfactants Derived from Dextran: A Study of Their Aqueous Solution Behavior

Summary: Amphiphilic polysaccharides are obtained by hydrophobic modification of a neutral bacterial polysaccharide, dextran. By reacting the polysaccharide with aliphatic epoxides (epoxyoctane and epoxydodecane) in dimethyl sulfoxide, a series of amphiphilic polymers is obtained which covers a large range of structural parameters (length of the polysaccharide, number and nature of hydrocarbon moieties). The solution behavior of dextran derivatives is first characterized by viscometric measurements in dilute and semi‐dilute domains. The effects of molecular parameters on polymer viscosity behavior are evidenced and discussed. Information on the state of aggregation of polymers is obtained by the use of static and dynamic light scattering. The presence of aggregates in the dilute domain is clearly evidenced and their structural characteristics are estimated (size, molecular weight and number of aggregation). The aggregates are shown to account for the viscometric results in the examined concentration range, relating their chemical parameters (hydrodynamic radius and molecular weight) to the macroscopic behavior of the solutions.

     

Swelling,Elasticity and Spatial Inhomogeneity of Poly(N,N‐dimethylacrylamide) Hydrogels Formed at Various Polymer Concentrations

Summary: The equilibrium swelling degree, modulus of elasticity and the spatial inhomogeneity of poly(N,N‐dimethylacrylamide) (PDMAAm) hydrogels were investigated over the entire range of the initial monomer concentration. The degree of dilution of the networks after their preparation was denoted by ν, the volume fraction of crosslinked polymer after the gel preparation. The linear swelling ratio of the gels increased linearly with increasing ν. Depending on the value of ν, three different gel regimes were observed: (1) For ν < 0.3, increasing ν decreases the extent of cyclization during crosslinking so that the effective crosslink density of gels increases with rising ν. (2) For 0.3 < ν < 0.7, increasing ν reduces the accessibility of the pendant vinyl groups during crosslinking due to steric hindrance at high polymer concentrations. As a result, the effective crosslink density of gels decreases with increasing ν. (3) For ν > 0.7, the modulus of elasticity increases sharply with increasing ν due to the increasing extent of chain entanglements in this high concentration regime. Static light scattering measurements on the gels show that the degree of spatial gel inhomogeneity in PDMAAm gels attains a maximum value at ν = 0.06. The appearance of a maximum as well as the ν‐dependence of scattered light intensities from gels was successfully reproduced by the theory proposed by Panyukov and Rabin.

Effective crosslink density ν_e of the hydrogels shown as a function of ν.     

Fibre-type specific expression of fast and slow essential myosin light chain mRNAs in trained human skeletal muscles

The fibre-type specific expression patterns of fast and slow isoforms of essential (alkali) myosin light chains (ELC) was analysed in trained, untrained and pathological human muscles. Biopsies from m. vastus lateralis of moderately trained and untrained persons, as well as highly trained endurance and strength athletes were analysed, by in situ hybridization, for the expression of the `fast' ELC 1f/3f and the `slow' ELC 1sb. We wanted to investigate if changes in the fibre-type specific ELC mRNA pattern could be used as markers for training adaptation, especially, if the mRNA of the slow ELC 1sb isoform would appear in type IIA fibres as a result of endurance training (Baumann et al. 1987). We found the fast/slow ELC expression patterns in the fibre types to be remarkably stable. Physiological stress, even high training loads, did not affect it. No IIA fibres expressing ELC 1sb mRNA were found. They could be detected, however, in pathological muscle samples, where fast/slow ELC patterns not found in normal muscles were frequent. Our data suggest that in healthy muscles, only a subset of the theoretically possible combinations of myosin heavy and light chain isoforms are expressed at the level of their mRNAs.