Influence of mefluidide on growth,development, and cell wall digestibility of sorghum

Application of mefluidide (N-[2,4-dimethyl-5-([(trifluoromethyl)sulfonyl]amino) phenyl]acetamide) inhibits plant development in perennial grasses. This study examined the effect of mefluidide on the morphological development and digestibility of sorghum. In the greenhouse, 5.9 × 10^–5 g active ingredient (a.i.) plant^–1 applied at the seedling, eight-leaf and boot stages reduced mean plant height 70%, 59%, and 2%, respectively. Heights were also reduced 14%, 15% and 35% by 5.9 × 10^–8, 5.9 × 10^–7 and 5.9 × 10^–6 gram a.i. plant^–1 applied at the eight-leaf stage. Field application of 0.26 or 0.52 kg ha^–1 mefluidide at either the eight-leaf or flagleaf stage reduced mean plant height of all cultivars. Basal tiller numbers increased 319% 28 d, and dry matter production was reduced 65% 42 d following mefluidide application at the eight-leaf stage. Treated stems were 34% higher and treated leaves were 7% higher in cellulase dry matter digestibility than control plants following mefluidide application at the eight-leaf stage. These results indicate that mefluidide application to vegetative stages in sorghum may enhance the forage value of the plants while it inhibits normal plant growth.     

人参根系发育形态学的研究

人参(Panax qinseng C. A. Meyer)属于直根系植物,有次生构造。一年生苗只具有主根和侧根。二年以上的人参常在根状茎上长出不定根,即人参根系包括主根和不定根及其各级分枝。主根初生木质部为三原型,侧根和不定根及其分枝多为二原型,偶见三原型。根系随参龄的增加而增大。每年末级分枝自基部于休眠前萎缩、脱落,并在萎缩部分的上一级支根内部产生越冬根原基,越冬根原基是翌年形成全部吸收根的基础。一年生人参由中柱鞘产生一圈初生树脂道,由形成层产生一圈(或二圈)次生树脂道,以后次生树脂道的圈数随参龄的增加而每年增加一圈,自第五年开始渐缓。根内淀粉粒含量随发育时期的变化而相应变化,其积累高峰出现在果后期。研究人参根系发育形态学不仅对全面正确认识人参根系具有理论意义,而且对改进人参栽培管理和评价人参质量具有指导意义。     

A note on the genomic consequences of regular bivalent formation and continued fertility in triploids

The genomic evolution of triploid plants with regular bivalent formation is discussed. The conclusion is reached that although all the progeny of an originally triploid individual will be triploid numerically, only part of the progeny will be triploid genomically. The consequences of this for triploid identification by means of chromosome morphology and isozyme numbers is discussed.     

The morphology,taxonomy and evolution ofRhodocoma (Restionaceae)

The vegetative and reproductive morphology, culm and rhizome anatomy and seed surface micromorphology ofRhodocoma are described. It is shown that this variation is best contained by recognizing three new species in the genus. These new taxa are described, and the phylogeny of the genus is investigated by cladistic analysis. The environmental parameters and distributions of the species are related to the cladogram. This suggests that the species are at present ecologically separated, and indicates that the speciation may have been sympatric. This is the first support for the hypothesis that sympatric speciation may have been important in the speciose Cape flora.     

Evolutionary implications of swimming behaviour in meiobenthic copepods

Body morphology is said to be the all important factor in determining swimming prowess in copepods. Fusion and differentiation of the body (tagmosis) is coupled with advance into the pelagic realm of the Gymnoplea and is thought, by the provision of a rigid thoracic tagma, to promote swimming efficiency. Thus pelagic copepods are believed to be secondarily derived from bottom dwelling predecessors. Experimental evidence is presented to show that the majority of bottom dwelling harpacticoid families, including the most primitive and the most advanced, have representatives that undergo active sustained swimming movements. Such a widespread occurrence is indicative of a conservative evolutionary trait. This primitive behaviour is linked to precopulatory association which takes place necessarily in the water column; it is a feature retained by representatives of all copepod orders. The implication of cephalic appendage vibration (feeding currents) is the essential feature in the swimming success of the Gymnoplea; planktonic efficiency in these is suggested to have evolved coincident with, rather than because of increased tagmosis.     

Morphological variation of Echinococcus granulosus protoscoleces from hydatid cysts of human and various domestic animals in Jordan

, and 1988. Morphological variation of Echinococcus granulosus protoscoleces from hydatid cysts of human and various domestic animals in Jordan. International Journal for Parasitology 18: 1111–1114. Rostellar hook morphology of protoscoleces was employed to study the possible existence of Echinococcus granulosus strains in humans and various domestic animals in Jordan. A distinct form in the donkey was evident as the protoscoleces from this host did not share any characteristics with those from the other hosts examined. Sheep, goats and cattle appeared to be affected by another form since the protoscoleces from their hydatid cysts shared six out of nine characteristics studied. Protoscoleces of camel and human cysts shared seven out of nine characteristics studied and they were different in six characteristics from protoscoleces from other hosts. Differences observed among the three forms may reflect strain variation of E. granulosus in this country.     

Description of Dolichodorus cobbi n. sp. (Nematoda: Dolichodoridae) with Description of Dolichodorus cobbi n. sp. (Nematoda: Dolichodoridae) with Morphometrics and Lectotype Designation of D. heterocephalus Cobb, 1914

Dolichodorus cobbi n. sp. is described and illustrated from soil around roots of "woods" on the Stanley Farm, Scott County, Arkansas. This species is distinguishable from others of the genus by its short tail projection. It is most closely related to D. marylandicus but differs in having a short tail projection, longer stylet, greater body length, larger c value, and also in position of excretory pore. A limited number of Cobb''s original specimens and drawings of D. heterocephalus were examined. A lectotype and paralectotype were designated to establish the taxonomic base for the genus. Cobb''s original modified labeled drawing of D. heterocephalus is also included. Morphometric data on D. heterocephalus from the type locality and several other populations are given. Some variations in female tail shape, body length, and stylet length were noted.     

Vital staining and acrosomal evaluation of bovine sperm

Dried smears prepared from vitally stained sperm were evaluated as a method of simultaneously determining sperm viability and acrosomal morphology. A combination Fast Green FCF-Eosin B stain was used. The stained smears were examined at × 1, 250 using differential interference contrast microscopy (DIC). For comparison, the percentage of sperm with intact acrosomes was also determined from wet smears using DIC. Acrosomal morphology was not altered by the staining procedure, as the percentage of intact acrosomes was similar whether quantitated from wet or stained smears. Absence of eosinophilic staining in the acrosome was used as an indication of sperm viability. The percentage of sperm with unstained acrosomes was highly correlated with the percentage of intact acrosomes quantitated from stained smears. Thus, vital staining provided an indication of sperm viability comparable to acrosomal integrity, a highly reliable technique. The major advantages of using dried stained smears were more thorough examination of individual sperm without sperm activity interference, simultaneous evidence of sperm viability and morphology, and the opportunity to delay evaluation. In addition, diluting spermatozoa in complex or simple media with or without egg yolk or follicular fluid did not interfere with subsequent staining or acrosomal evaluation.     

Critical nuclear DNA size and distribution associated with S phase initiation

Using HeLa S-3 cells synchronized by selective detachment, in this paper we report a parallel study of nuclear morphology and autoradiography grain patterns between middle G₁ and middle S phases: Our results show two distinct [³H]-thymidine labeling patterns. The first “peripheral” labeling pattern has a characteristic nuclear size distribution, in contrast to the heterogeneous and varying size distributions of Feulgen-stained nuclei, and apparently is characteristic of very early S phase. The sizes of the second labeling pattern—homogeneous or inhomogeneous grain distribution throughout the nucleus—are equal or larger than the first and vary with S phase progression. Together, the corresponding nuclear sizes of the labeled nuclei represent the larger extreme of nuclear areas, and the labeling index closely parallels the fraction of nuclei with areas larger than the minimum size of the labeled nuclei. These results suggest a characteristic nuclear size (reflecting unique intranuclear DNA distribution) as a necessary, if not sufficient, requirement for S phase initiation. Parallel experimentation with rat liver cells—synchronized in vivo by partial hepatectomy and analyzed by thin section autoradiography—confirms the existence of a peripheral labeling pattern in both the very early part and the very late part of S phase, which reconciles our data with previous results and points to the fact that both initiation and termination sites for DNA replication are near the nuclear periphery.