Behavior of lactating rats in a dual-chambered maternity cage

Videotape sampling of behavior in a dual-chambered apparatus indicates that the continuous monitoring of the amount of time a mother spends in the cage with its litter can be taken as a valid reflection of maternal behavior. Nursing is the principal behavior of lactating females while in the compartment with their litters; lying still, consummatory behavior, and activity occur with greater frequency in the cage away from the litter. Both the time that mothers spend with their litters and nursing behavior displayed a 24-hr rhythm with crest values occurring during the period of light.     

Structure fine du rein de l'Epinoche (Gasterosteus aculeatus L.) au cours de sa transformation muqueuse

Résumé Pendant la période de reproduction, les néphrons du rein de l'Epinoche mâle subissent d'importantes modifications de structure sous l'action des hormones sexuelles. Au niveau de chacun d'entre eux, se différencient deux segments distincts par leur fonction et par leur cytologie. Le segment urinaire, très court, est formé de cellules identiques à celles du jeune, qui remplissent leur fonction d'excrétion. Le segment glandulaire, plus volumineux, subit une transformation muqueuse et élabore une sécrétion qui sert à construire le nid. L'évolution de ces deux segments est étudiée au cours de la période de reproduction et les modifications cytologiques correspondantes sont décrites.

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Fine structure of the kidney of the three-spined-stickleback (Gasterosteus aculeate L.) during its mucous transformation

Summary Under the action of sexual hormones the nephrons of the kidney of the male three-spined-stickleback undergo considerable transformations during the breeding period. They differentiate into two segments which differ from one another in function and cytology. The cells of the urinary segment are identical to those of the young fish. They have an excretory function. The glandular segment undergoes a mucous transformation and synthesizes a secretion which is used for the building of the nest. The cytological transformations occuring at the level of these two segments during the breeding period are described with special attention to the mucous cells.

     

Second virial coefficient of alpha-crystallin

Light scattering studies were performed on bovine alpha-crystallin measuring the scattering intensities as a function of scattering angle, concentration, and temperature. The data yielded the molecular weight, radius of gyration, and second virial coefficient of alpha-crystallin at different temperatures. The second virial coefficient increased with increasing temperature. Both the enthalpy and entropy of solution of alpha-crystallin are positive. The Flory theta temperature was found to be 271 K.     

Body shape and differences between species

The variation of body shape among prosimians is reviewed. Special emphasis is placed on the selective advantages, that is the mechanical reasons, to which variants of the locomotor apparatus can be traced back. There are differences found in the cheiridia, but at present they cannot be explained in terms of mechanics; there is nearly no knowledge about the mechanical meaning of their diversity. Myological characteristics of taxa can be explained mechanically, but this has not yet been done. Well known are variations of body proportions. These discriminate higher taxa, and are largely coincident with the often-used locomotor categories. In spite of this, there are only few sound arguments about the real biomechanic value of characteristic proportions for a given locomotor mode. What is known on this field, is reviewed. Progress can be made only, if the mechanical conditions, set by postural behavior and locomotion, are understood completely. The subtle distinctions between lower taxonomic units can normally be identified only on the basis of detailed and quantified analyses of movements on one hand, and of biometrics on the other. In the few cases in which such studies have been made, the differences of morphology fit to the mechanical requirements of locomotion which also differ only in quantitative details.     

Coaction of blue/ultraviolet-A light and light absorbed by phytochrome in controlling growth of pine (Pinus sylestris L.) seedlings

Photomorphogenesis is a conspicuous feature in conifers. In the case of the shade-intolerant Scots pine (Pinus sylvestris L.), control of stem growth by light is well expressed at the seedling stage and can readily be studied. The present data show that hypocotyl growth is controlled by the far-red-absorbing form of phytochrome (Pfr). However, the Scots pine seedling requires blue or ultraviolet (UV-A) light to become fully responsive to Pfr. Blue/UV-A light has no direct effect on hypocotyl growth and its action appears to be limited to establishing the responsiveness of the seedling to Pfr. This type of coaction between phytochrome and blue/UV-A light has been observed previously in a number of angiosperm seedlings. With regard to the high irradiance reaction of phytochrome in long-term far-red light the pine seedling deviates totally from what has been observed in etiolated angiosperms since continuous far-red light has no effect on stem growth.Abbreviations B light of wavelength between 500 and 400 nm - FR standard far-red light - HIR high irradiance reaction of phytochrome - R high-fluence-rate red light (_R = 0.8) - RG9-light long-wavelength far-red light defined by the properties of the Schott RG9 glass filter (_RG₉<0.01) - = Pfr/Ptot wavelength-dependent photoequilibrium of the phytochrome system (far-red-absorbing form of phytochrome/total phytochrome) - UV-A near ultraviolet light of wavelength between 400 and 320 nm - W white light Research supported by a grant from the Deutsche Forschungsgemeinschaft (Schwerpunkt Physiologie der Bäume).     

“引黄济青”输水沿线水生生物分布与蓄水库富营养化关系的研究

“引黄济青”是国家“七五”重点工程,由黄河下游博兴县境内打渔张闸引水,在渠首沉沙后,再经惠民、东营、潍坊和青岛的10个县区约253km的明渠输送,到达唠山县棘洪滩蓄水库蓄存,实现向青岛市日供水3.0×10~5m~3。明渠输水过程中,来白沿线的营养物质会污染水体,加之输水在库中滞留时间长,会不会发生富营养化,这是社会普遍关注的问题。     

Diurnal variation of corticotropin-releasing factor binding sites in the rat brain and pituitary

Summary 1. Corticotropin-releasing factor (CRF) is thought to be involved in the regulation of the diurnal activity of the hypothalamus-pituitary-adrenal (HPA) axis and to act as a neurotransmitter in the brain. To date it is unknown whether the binding sites of the central CRF system are subject to diurnal variations. 2. We measured the number of CRF binding sites over the course of a complete 24-hr light-dark cycle in the pituitary, amygdala, bed nucleus of the stria terminalis (BNST), cingulate cortex, visceral cortex, paraventricular nucleus of the hypothalamus, hippocampus, and locus ceruleus of rats byin vitro receptor autoradiography with iodinated ovine CRF. A 24-hr time course was also established for plasma CRF and corticosterone. 3. The diurnal pattern of plasma CRF does not correlate with the pattern of plasma corticosterone. Within the brain, CRF binding in the basolateral nucleus of the amygdala showed a U-shaped curve with maximum levels in the morning and a wide hallow between 1500 and 0100. A biphasic profile with a small depression in the afternoon and a more pronounced depression in the second half of the activity period is characteristic for the other brain areas and the pituitary. The profile for the pituitary correlates with those for the BNST and the area of the locus ceruleus. Furthermore, the diurnal pattern of CRF binding sites in the BNST correlates with that of the hippocampus, and the daytime pattern of the visceral cortex is similar to that of both the hippocampus and the BNST. 4. Since the CRF-binding profiles in the brain and the pituitary clearly differ from the profiles of both plasma CRF and corticosterone, one may assume that the diurnal pattern of central CRF binding sites is not directly coupled to the activity of the HPA axis.