(n.) A plant that bears naked seeds (i. e., seeds not inclosed in an ovary), as the common pine and hemlock. Cf. Angiosperm.
Example Sentences:
(1) Agrobacterium strains that were more tumorigenic on gymnosperms were more effectively induced by coniferin.
(2) The placement of these introns within the pine lpcr gene is identical to that observed in pea (Pisum sativum), suggesting conservation in gene organization between dicot and gymnosperm species.
(3) The genus Ginkgo is a north temperate gymnosperm taxon represented by fossilized leaves and wood from the early Jurassic through the Pliocene, and by the living species G. biloba native to eastern China.
(4) Genealogical relationships among gymnosperm taxa cannot be deduced unambiguously on the basis of rRNA data.
(5) As the time of divergence of at least some of these gymnosperm taxa is traceable back to the early Carboniferous, it may be concluded that the genealogical splitting of gymnosperm and angiosperm lineages occurred before this event, at least 360 million years ago, i.e., much earlier than the first angiosperm fossils were dated.
(6) These results on the gymnosperm spruce leaves, in which greening proceeds in complete darkness, being independent of the development of the water-splitting system in light, were discussed in relation to previous observations on angiosperm leaves, in which both greening and the activity generation proceed in the light.
(7) Minisatellite applications have been restricted to tetrapods, but here we demonstrate that one probe, the M13 repeat probe previously used to detect minisatellites in humans and bovines, also reveals minisatellite-bearing endonuclease fragments in gymnosperms and angiosperms.
(8) Partial sequences of 18s rRNA were obtained for 2 gymnosperms and 12 angiosperms from a wide range of families and these were analyzed with 5 other published sequences to form a phylogenetic tree.
(9) A study on the wild and cultivated medicinal plants used in the Peninsula Sorrentina (southern Italy) is reported; 129 plants distributed among 53 different families beloning to Pteridophytes, Gymnosperms and Angiosperms are used in the treatment of various human diseases.
(10) Sixty-seven widely accepted prescriptions involving 49 plant species (one species of fungi, two species of ferns, one species of gymnosperms and forty-five species of angiosperms) are presented along with details on uses.
(11) With this procedure, high-molecular-weight DNA suitable for Southern transfer experiments has been isolated from over 30 plant species including angiosperms (both dicots and monocots), a gymnosperm, members of other divisions, and two microorganisms.
(12) A 712-base portion of the mitochondrial gene coxI and the corresponding portion of the coxI transcript were amplified by PCR and by RT-PCR, respectively, from the gymnosperm western red cedar.
(13) The duration of meiosis has been estimated in about 70 organisms, including two prokaryotes (yeast and Chlamydomonas) and the following eukaryotes: 1 Basidiomycete (Coprinus lagopus), 2 Gymnosperms (Larix decidua and Thuja plicata gracilis).
(14) This finding throws new light on the taxonomy of the gymnosperms.
(15) The free energy (delta G) analysis of 5S rRNAs from gymnosperms, angiosperms and the other higher plants revealed that the free energy of this ribosomal RNA decreases with evolution.
(16) In addition, one can speculate that an antigen in Cupressus sempervirens is cross-reactive with SBP, the major allergen of Sugi, suggesting that there is a closer relationship between the Taxodiaceae family and the Cupressaceae family than between these two families and the other families of the gymnosperms.
(17) Gel permeation profiles demonstrated significant depolymerization of 14C-sidechain-labeled syringyl lignin, a 14C-sidechain-labeled syringyl-guaiacyl copolymer (angiosperm lignin), and depolymerization of 14C-sidechain- and 14C-ring-labeled guaiacyl lignins (gymnosperm lignin).
(18) The data obtained suggest that the divergence of all the main groups of extant gymnosperms occurred after the branching off of the angiosperm lineage.
(19) cDNAs encoding three different LHC I polypeptides (Type I, Type II and Type III) from the gymnosperm Scots pine (Pinus sylvestris L.) were isolated and sequences.
(20) The only inference may be that the taxon Gnetopsida is an artificial one, and Gnetum and Ephedra belong to quite different lineages of gymnosperms.
Spermatozoid
Definition:
(n.) The male germ cell in animals and plants, the essential element in fertilization; a microscopic animalcule-like particle, usually provided with one or more cilia by which it is capable of active motion. In animals, the familiar type is that of a small, more or less ovoid head, with a delicate threadlike cilium, or tail. Called also spermatozoon. In plants the more usual term is antherozoid.
Example Sentences:
(1) The spermatozoid content of DNA was analyzed using the Feulgen staining method and the relative content of histone proteins by the Alfert and Geschwind staining method.
(2) The presence of antibodies against spermatozoids was considered as an important factor associated with AIDS and previous states of the AIDS detected by OKT8 greater than 30% of lymphocytes.
(3) The authors analyzed in 196 sterile women the ovulation mucus by the microagglutination test and found a high anti-spermatozoidal activity in 24 (12%) women.
(4) The predominant cytologic features were granulomatous inflammation (nontuberculous and non-foreign body) and spermatozoids (intrahistiocytic or as extracellular spermatic debris).
(5) The Hynie method was observed to have some advantages over other methods: it is easy to apply and provides exact data which are useful in determining spermatozoidal deficiencies in sterility cases.
(6) In animals of both subgroups the spermatozoid concentration in the epididymal suspension was lowered and the relative content of spermatozoids with morphologically abnormal heads in suspension smears was increased.
(7) The microtubules on the outside of the nucleus of the mature spermatozoid of Pteridium form a complex with the envelope, and the perinuclear space is eliminated.
(8) A relationship between transferrin and spermatozoid concentration in sperm was shown.
(9) This membrane also undergoes growth, the outer layer extending into the cytoplasm and surrounding spermatozoid mitochondria.
(10) This layer may be important in preventing other spermatozoids from fusing with the egg.
(11) Similarly, the incubation of spermatozoids obtained from the tail of the epididymis with CPhM causes them to produce only 7% fertilization, instead of the normal rate of 80%.
(12) The prognosis depends on the alterations seen on the sperm count parameters; but there is no threshold figure under which no pregnancy is observed (except for zero), concerning the count, the gradual mobility or the morphology of the spermatozoids.
(13) The quantitative yield is given for DNA and RNA preparations from the mentioned objects, the molecular weight of roach and bream DNA, nucleotide composition of roach DNA as well as fractional composition of bream spermatozoids RNA are determined.
(14) The ultrastructure of the mature spermatozoid of Marsilea vestita was studied after its release from the microspore and prior to its penetration of the egg.
(15) After spermatozoid penetration, a new extracellular layer appears above the surface of the egg, beginning in the region of sperm penetration and spreading across the top of the egg.
(16) Changes in the nucleus and the cytoplasm of both the spermatozoids and spermatides were revealed at the early stages of their formation.
(17) Circadian rhythm of activity of 3H-leucine incorporation into antheridial cells of Chara vulgaris, in natural photoperiod was compared with changes in mitotic activity of antheridial filament cells which form spermatozoids.
(18) Any abnormality often severely compromises the ability to fertilize spermatozoids.
(19) The various criteria of the sperm count then examined, emphasizing the importance of studying the morphology, on optical as well as electron microscopy, since it is the spermatozoid's morphology as well as their mobility that differentiate fertile man from infertile ones.
(20) is fertilized by small biflagellate spermatozoids and both monoecious and dioecious species are found.