نتایج جستجو برای: micropyle
تعداد نتایج: 189 فیلتر نتایج به سال:
Fresh fecal samples from 35 Japanese serows Capricornis crispus (Temminck, 1845), and 5 Formosan serows Capricornis swinhoei Gray, 1862, were collected between October 1998 and March 1999. Eimeriid coccidians were found in 12 (34%) Japanese serows and in 1 (20%) Formosan serow. Three Eimeria species were found, and 2 are described here as new. The third species is consistent with the descriptio...
In flowering plants, pollen deposited upon the stigma of a flower germinates to produce a pollen tube that must grow through the maternal transmitting tract and into the micropyle of an ovule in order to release its two sperm cells for double fertilization with the egg and central cell. In addition to pollen tubes being useful for studying polar cell growth, the myriad interactions between the ...
In flowering plants, double fertilization is one of the defining features of reproductive development (Raghavan, 2003). Double fertilizationwas first discovered in 1898 byNawaschin. It involves a complex series of interactions between essentially three plants—the male gametophyte (MG), the female gametophyte (FG), and the sporophyte—culminating in the fusion of sexual cells and nuclei and the f...
Since January 1975, 104 of 361 (29%) kangaroo rats (Dipodomys spp.) examined for Coccidia had oocysts in their feces. These included 32 of 71 (45%) D. agilis from California (3 of 8, 38%) and Baja California Norte (29 of 63, 46%); none of 18 D. deserti from Sonora, Mexico; one of one D. gravipes from Baja Norte; 43 of 124 (35%) D. merriami from California (1 of 4, 25%), New Mexico (16 of 49, 33...
Life cycle of Eimeria krijgsmanni-like coccidium isolated from the feces of naturally infected mice purchased from commercial sources was examined. The parasite was purified by single oocyst isolation and maintained by passage in the mice before experiments. The sporulated oocysts were ovoid or ellipsoid, measuring 19.3 x 14.8 microm on average. One or two small polar granules were present. Mic...
This research aimed to assess the toxicity of the pesticides abamectin 18 CE (0.02 g a.i. L-1), carbaryl 480 SC (1.73 g a.i. L-1), sulfur 800 GrDA (4.8 g a.i. L-1), fenitrothion 500 CE (0.75 g a.i. L-1), methidathion 400 CE (0.4 g a.i. L-1), and trichlorfon 500 SC (1.5 g a.i. L-1) as applied in integrated apple production in Brazil on the survival, oviposition capacity, and egg viability of the...
Most knowledge concerning Mesozoic Era floras has come from compression fossils. This has been augmented in the last 20 years by rarer permineralized material showing cellular preservation. Here, we describe a new genus of anatomically preserved gymnosperm seed from the Callovian-Oxfordian (Jurassic) Oxford Clay Formation (UK), using a combination of traditional sectioning and synchrotron radia...
Primary dormancy in tomato (Lycopersicon esculentum cv. Moneymaker): studies with the sitiens mutant
Intact wild-type tomato (Lycopersicon esculentum cv. Moneymaker) seeds do not complete germination to the same percentage or at the same speed as intact ABA-deficient sitiens (sit") mutant seeds when seeds of both genotypes are imbibed on polyethylene glycol (PEG) solutions of -0 .3 to —1.5 MPa osmotic potential. However, if the thicker testas of wild-type seeds are removed (stripped) from the ...
BACKGROUND AND AIMS The pollination drop is a liquid secretion produced by the ovule and exposed outside the micropyle. In many gymnosperms, pollen lands on the surface of the pollination drop, rehydrates and enters the ovule as the drop retracts. The objective of this work was to study the formation of the pollination drop in Juniperus communis, its carbohydrate composition and the response to...
The invasiveness of cancer cells resembles the normal behavior of cells that migrate into surrounding tissues during development. For example, the border cells in the Drosophila ovary undergo a partial epithelial to mesenchymal transition and invade the neighboring cluster of germline cells, migrating to the oocyte border. Once there, they provide patterning information to the oocyte and produc...
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