Structural reactions to polarized light of microvilli in photoreceptor cells of the moth Spodoptera

Summary Intact armyworm moths (Spodoptera exempta, Farn. Noctuidae) were illuminated by polarized monochromatic light to induce structural changes in the rhabdomeres of the compound eyes. The degree of distortion of their microvilli depends on the light energy absorbed per time unit. Under polarized light, the number of quanta absorbed varies with the position of the plane of polarization relative to the axis of the microvilli (intrinsic dichroism). Therefore, in Spodoptera, different degrees of deformations could be demonstrated in differently oriented rhabdomeres of both types of ommatidia. Moreover, in rhabdoms of the lobed type with fan-like arranged microvilli, different reactions were regularly seen in differently oriented microvilli of one rhabdomere. This indicates that microvilli may react to light individually.Supported by Deutsche Forschungsgemeinschaft, Sonderforschungsbereich 114 (Bionach)     

Fusion of hamster and pig zona-free eggs stimulated by boar and guinea pig sperm at fertilization in vitro

In the course of in vitro fertilization of zona-free hamster and pig eggs by boar and guinea-pig spermatozoa it was observed that homologous and heterologous eggs fused together, forming cell hybrids between two or more cells. The fusogenic activity was attributed to spermatozoa and this was the hypothesis tested. The fusogenic activity (coinciding with sperm penetration activity) was dependent on the duration of sperm preincubation, which may be regarded as capacitation in vitro. Fusion occurred only after 3 hr of sperm preincubation and a narrow optimum was detected at 4–4.5 hr. Fusion of eggs was also dependent on sperm concentration. A relatively high proportion of fusions was observed at a sperm concentration of 4.0 × 10⁴ per ml and an optimum was attained at a concentration of 5.0 × 10⁵ per ml. The first fusions were observed at 90 min after semination. After 3 hr more than a half of the eggs reacted, and by 20 hr of incubation 80% of ova were fused. The fusability of eggs was tested and found to occur at 14 hr after ovulation. The fusion process was also studied using transmission electron microscopy. It is supposed that the process of egg fusion may be caused either by a similar mechanism to sperm-egg fusion, or by products released during the sperm acrosome reaction.     

New, rapid methods for purifying alpha-actinin from chicken gizzard and chicken pectoral muscle

We introduce two new, rapid procedures. One is specifically designed for isolating alpha-actinin from skeletal and the other for isolating alpha-actinin from smooth muscle. Approximately 20 mg of greater than 95% pure alpha-actinin can be obtained/100 g of ground chicken pectoral muscle in just 4 days. The smooth muscle protocol yields 2.7 mg of greater than 99% pure alpha-actinin/100 g of ground gizzard after just 5 days. Differences in protein contaminants and in the extractability of alpha-actinin necessitated the development of separate isolation procedures for the two muscle types. Antibody prepared against the purified gizzard alpha-actinin reacted with alpha-actinin from skeletal, cardiac, and smooth muscle in immunodiffusion. Anti-alpha-actinin reacted only with alpha-actinin from crude extracts of skeletal and smooth muscle on Staph A gels. Anti-alpha-actinin stained Z-bands from skeletal muscle in indirect immunofluorescence microscopy and stress fibers from baby hamster kidney fibroblasts and mouse mammary epithelial cells in the characteristic punctate pattern observed by other workers (Lazarides, E., and Burridge, K. (1975) Cell 6, 289-298). These two methods for purifying alpha-actinin from skeletal and smooth muscle represent a significant improvement over that published previously.     

The influence of the electric diffusion potential on delayed fluorescence light curves of chloroplasts treated with 3-(3,4-dichlorophenyl)-1,1-dimethylurea

The potassium salt-induced transient increase of delayed fluorescence yield was studied in pea chloroplasts treated with 3-(3,4-dichlorophenyl)-1,1-dimethylurea.A simple kinetic model is proposed to account for the actinic light intensity dependence of the delayed fluorescence enhancement by the transmembrane diffusion potential induced by sudden salt addition. The electric field dependence of the rate constants for the recombination of primary separated charges with and without subsequent electronic excitation of reaction center chlorophyll was obtained.From the value of enhancement of delayed fluorescence by salt concentration gradients at saturating actinic light intensity, it is concluded that the distance, normal to thylakoid membrane surface, between the primary acceptor and the donor of Photosystem II is smaller than the membrane thickness.     

Histologic study of the teleost liver. II. The blood vessel system

In the liver of the teleosts investigated in the present study the sinusoidal region shows a space of DISSE, which contains numerous microvilli originating from the hepatocytes. In some species, especially in Tetraodon leiurus, there are also bundles of collagenous fibrils. In the DISSE's space of larger sinusoids (transition sinusoids) sections of filament-rich cells are found. These are sometimes interconnected by desmosomes and can be interpreted as processes of smooth muscle cells from the region of the venae hepaticae. The endothelium of smaller sinusoids is fenestrated and shows micropinocytotic activity. The endothelia of the transition sinusoids and of the venae hepaticae are endowed with structures, which can be interpreted as macrovesicles. In the sinusoidal region true KUPFFER-cells and ITO-cells could not be observed. Nevertheless, the close location of granulocytes to the sinusoidal endothelium suggests that phagocytotic processes cannot be excluded for the sinusoidal region. Exceptionally, in Hemihaplochromis multicolor there were also signs of possible phagocytosis by sinusoidal endothelial cells. The chemomorphology of the sinusoidal region, above all the evidence of alkaline phosphatase, shows great differences between species. The examination of the larger blood-vessels in the liver of Haplochromis burtoni reveals venae portae with very thin walls and venae hepaticae with thick walls, which contain smooth muscle cells. Granulocytes and melanocytes are abundant in the wall of the venae hepaticae. This phenomenon indicates that the defence-functions, which in the liver of higher vertebrates are carried out by the sinusoids (KUPFFER-cells), are undertaken by the region of the venae hepaticae in the liver of Haplochromis burtoni, which is free of KUPFFER-cells. On their extrahepatic course the venae portae are surrounded by a sleeve of exocrine pancreatic tissue, which accompanies the vessels deep into the liver. The pancreatic cells bordering the thin-walled venae portae have sparse microvilli indicating a transfer of substances between venous blood and pancreas similar to the sinusoidal region of the liver. Furthermore, the investigation resulted in a clue to the innervation of the exocrine pancreas.     

New steroidal saponins of Agave americana

Two new saponins, agavasaponin E and agavasaponin H have been isolated from the methanolic extract of Agave americana leaves and their structures elucidated. Agavasaponin E is 3-O-[β-d-xylopyranosyl-(1→2glc1)-α-l-rhamnopyranosyl-(1→4)-α-l-rhamnopyranosyl-(1→3glc 1)-β-d-glucopyranosyl-(1→4)-β-d-glucopyranosyl-(1→4)-α-d-galactopyranosyl]-(25R)-5α-spirostan-12-on-3β-ol, whereas agavasaponin H is 3-O-[β-d-xylopyranosyl-(1→2 glc 1)-α-l-rhamnopyranosyl-(1→4)-α-l-rhamnopyranosyl-(1→3 glc 1)-β-d-glucopyranosyl-(1→4)-β-d-glucopyranosyl-(1→4)-β-d-galactopyranosyl]-26-O-[β-d-glucopyranosyl]-(25R)-5α-furostan-12-on-3β,22α,26-triol.     

Steroidal saponins of Yucca filamentosa: Yuccoside C and protoyuccoside C

Two new saponins, yuccoside C and protoyuccoside C, have been isolated from the methanolic extract of Yucca filamentosa root and their structures elucidated. Yuccoside C is 3-O-[α-d-galactopyranosyl-(1 → 2)-β-d-glucopyranosyl-(1 → 4)-β-d-glucopyranosyl]-(25S)-5β-spirostan-3β-ol, whereas protoyuccoside C is 3-O-[α-d-galactopyranosyl-(1 → 2)-β-d-glucopyranosyl-(1 → 4)-β-d-glucopyranosyl]-26-O-[β-d-glucopyranosy]-(25S)-5β-furostan-3β,22α,26-triol.