Relationship between muscle fiber types and sizes and muscle architectural properties in the mouse hindlimb

Skeletal muscle fiber and architectural properties both contribute to the functional behavior of a muscle. This study uses discriminant analysis and mathematical modeling to identify the structurally and functionally significant properties. The architectural properties of fiber length, muscle length, and pennation angle are found to be the most structurally significant parameters, whereas fiber length, muscle length, and fiber type distribution are found to be most functionally determining. Architectural speed and fiber type do not appear to be complimentary (i.e., the architectural determinant of sspeed, fiber length, is not associated with fibers of high intrinsic velocity). However, there does seem to be a synergistic relation between the two property classes and force production. Muscles with large physiological cross sectional areas (PCSAs) tend to contain a greater proportion of larger, faster fibers. Structurally or morphologically significant parameters are not always found to have a large functional effect. Pennation angle, though one of the most structurally significant variables, was found to have very little functional effect. © 1994 Wiley-Liss, Inc.     

Proteins in chromosome banding

Nuclei were isolated from Chinese hamster cells, treated with hypotonic KCl, fixed in acetic methanol, and either air-dried in glass tubes (in situ) or left in suspension (in vitro). These preparations were then exposed to a variety of G-banding treatments, including the 2 × SSC, urea, NaCl-urea, and trypsin methods. The proteins extracted into the treatment solution and those remaining in the nuclei were analyzed by SDS polyacrylamide gel electrophoresis. The three former treatments extracted specific subsets of the total nuclear nonhistone proteins into the treatment solution. Some of the extracted nonhistones were common to all treatments while others were unique to a particular treatment. Variable amounts and types of the histones were also extracted by these treatments, but significant quantities of all of these proteins still remained in the nuclei afterwards. The trypsin treatment appeared to degrade some of the nonhistones, while other non-histones, as well as the histones, were relatively resistant to trypsin digestion. Although there were a few differences in the residual proteins found in the nuclei after the various G-band treatments, the overall electrophoretic patterns of these proteins were generally similar. The results indicate that the G-banding techniques induce specific and reproducible changes in the proteins of isolated nuclei. If these banding treatments induce similar changes in the proteins of mitotic chromosomes, such alterations might be involved in mechanisms of chromosome banding.     

AUSWIRKUNGEN VON INSEKTIZIDBEHANDLUNGEN AUF DIE EPIGÄISCHEN RAUBARTHROPODEN IN GETREIDEFELDERN,INSBESONDERE DIE LAUFKÄFER (COLEOPTERA,CARABIDAE)

Zusammenfassung Die Ergebnisse wurden mit Bodenfallen in Getreidefeldern erarbeitet. Fenitrothion beeinflußte bei Flugzeugausbringung in normaler Dosierung (600 g/ha in 40 1 Wasser) nur die Populationsdichte von Pterostichus vulgaris und P. niger vorübergehend. Eine Spritzung mit erhöhter Dosierung (900 g/ha in 350 1 Wasser) wirkte sehr stark auf die fünf häufigsten Carabidenarten ein. Parathion-äthyl beeinflußte in normaler Dosierung (125 g/ha in 300 1 Wasser) bei einer Behandlung Anfang Juni besonders einschneidend die Frühlingstiere, Ende Juni stark die Frühlings- und die Herbsttiere. In doppelter Dosierung reduzierte es alle wichtigen Prädatorengruppen sehr deutlich. Parathion-methyl (Staub) wirkte bei Ausbringung auf feuchte Pflanzen (200 g/ha) nicht stark auf die epigäischen Räuber. Nur kletternde Arten (Staphyliniden und Agonum dorsale) wurden geschädigt. Methoxychlor wirkte als Spritzmittel (600 g/ha in 300 1 Wasser) stark auf die großen Carabiden, während die kleinen Laufkäferarten, die Staphyliniden und Spinnen nicht beeinflußt wurden. Methoxychlor-Staub, auf die feuchten Pflanzen ausgebracht (1000 g/ha), beeinflußte die epigäischen Räuber nicht. Eine Randbehandlung eines Winterrapsfeldes mit Methoxychlor-Staub störte die Besiedlung des Feldes durch Carabiden und Staphyliniden nicht.

---

Summary The influence of some insecticides often used in agriculture upon the terrestrial predaceous arthropods was investigated by pitfall trapping on cereal fields of about 10 hectares each, half the area of which was treated.Fenitrothion, sprayed by aeroplane at the normal dosage (600 g/ha in 40 1 water) influenced the abundance of Pterostichus vulgaris and P. niger only, for a short period. Spraying fenitrothion at a higher dosage (900 g/ha in 350 1 water) killed a high percentage of the five most common carabid species.Parathion-ethyl at the normal dosage (125 g/ha in 300 1 water), sprayed at the beginning of June reduced numbers of spring breeders especially (e.g. Pterostichus cupreus). Sprayed at the end of June, it influenced both spring and autumn breeders (e.g. P. vulgaris). Rain, falling one day after the insecticide treatment, did not alter its effect upon the terrestrial predators. At a higher dosage (250 g/ha) parathion-ethyl reduced numbers of all predators to a large extent, but not very much more than at the normal dosage.Parathion-methyl dust, applied to moist plants (200 g a.i./ha), did not influence all terrestrial predators, but only those species which also climb up the plants (some staphylinids and Agonum dorsale).Methoxychlor emulsion, sprayed at a dosage of 600 g/ha in 300 1 water, killed the bigger ground beetles only (Carabus spp. and P. vulgaris), but not the smaller ones (Agonum dorsale and Bembidion lampros), the staphylinids and the spiders. Methoxychlor, dust, applied to moist plants (1000 g a.i./ha) did not influence the terrestrial predators. Treating the edge only (ca. 20 m) of a winter-rape field with methoxychlor dust did not prevent the colonization of the field by carabids and staphylinids. It is recommended, therefore, to treat the field edges only, which should control most cereal pests.

     

Flow cytometric determination of zoospore DNA content and population DNA distribution in cultured Pfiesteria spp. (Pyrrhophyta)

The relative cellular DNA content from 23 different clonal cultures of Pfiesteria spp. zoospores was determined using a DNA fluorochrome and flow cytometry. Significant differences between Pfiesteria piscicida and P. shumwayae were detected, both in mean zoospore DNA content and population cell cycle DNA distribution. Intraspecific differences in DNA content were found between clonal zoospore cultures established from different geographical regions. Long-term cultures (years) of P. piscicida were available for testing, and a negative correlation was observed between zoospore DNA content and time in culture. Zoospore cell cycle-related DNA distributions were also markedly different between the two species in these clonal cultures. In most cultures tested, P. piscicida zoospores exhibited bimodal DNA flow histograms with G1-S-G2+M distributions, typical of eukaryotic asynchronously cycling cells. In contrast, cultures of P. shumwayae zoospores exhibited one DNA peak distribution, indicative of synchronized cells. The data are consistent with the hypothesis that P. shumwayae zoospores are interphasic cells, and mitosis in zoospore cultures of this species predominantly occurs as benthic or adherent non-motile division cysts. Light microscopy observations of the nuclear condition of electrostatically sorted zoospores of each Pfiesteria species also support this hypothesis. If highly conserved, this disparity in modes of vegetative reproduction would ramify the population dynamics of the two Pfiesteria species.