Pollen grain

How does the diameter of airborne pollen grains compare with the diameter of a human hair ... 

Forest systems also act as sources of CO2 when controlled or uncontrolled burning and decay of litter occur. In addition, release of ethylene occurs during the flowering of various species. One additional form of emission to the atmosphere is the release of pollen grains. Pollen is essential to the reproductive cycle of most forest systems but becomes a human health hazard for individuals susceptible to hay fever. The contribution of sulfur from forests in the form of dimethyl sulfide is considered to be about 10-25% of the total amount released by soils and vegetation (12). 

Immunogold localization of the pectic epitope has been performed on different types of cells cell suspensions, roots, shoots, meristems, coleoptiles, pollen grains, protoplasts from different species carrot, sugar beet, tobacco, oat... The pattern of labeling was always the same polygalacturonic acid was essentially located on the material expanded at three-way junctions between cells or lining intercellular space, but was not found in primary walls. No epitope could be located close to the plasma membrane (Fig. lO.a). Middle lamellae far from junction zones and walls of meristematic cells were never labeled. 

Plants are detrimental in many ways to the health and well-being of man. It is difficult to quantify the health aspects of weeds. Weeds known to produce allergenic reactions in humans can be divided into two major groups. One group produces skin eruption as a result of bodily contact with the plant, while the other produces symptoms usually affecting the respiratory tract through inhalation of pollen grains. 

Plants causing allergenic reactions by inhalation of pollen grains are numerous and widely distributed. Plant families whose pollen causes allergic reactions include Gramineae,... 

Morphosynthesis of complex inorganic forms using pollen grain templates. Chemical Communications, 2784-2785. 

Statistical analysis One hundred pollen grains were examined on each slide and 100 microspores were analysed per slide. Counting was done in four or five replicates (the number of Petri dishes per treatment). Results were expressed as mean SEM. The relative standard deviation (RSD) was 5-6% (n = 400-500 microspores per one variant P =0.95). 

Fig. 11 Fluorescence of pollen grain from Hippeastrum hybridum stained with azulene 10-5 (left, bright lightening of cell wall and less intensive emitted nucleus in centre) or pollen tube stained with colchicine 1CT7 M (right, lightening parts of pollen tube may be tubulinbinding sites).

The staining of germinated pollen of Hippeastrum hybridum with colchicine demonstrates green-yellow emission of microtubules (better vision in black-white image) around nuclei of pollen grain (threads at the division of the nucleus) and spermium on the tip of the pollen tube, where spermium moves, as well as in some bridge sites of the tube (Fig. 10). The similar fluorescent allelochemicals may be also used as fluorescent dyes at the cellular diagnostics (Roshchina, 2005 b). 

While more commonly used to count or otherwise characterize cells for medical applications, Coulter Counters and flow cytometry technique can also be applied to the analysis of pollen grains in allelopathic studies. They are quite useful in determining the size and number of pollen grains. The technique is often used for assessing the production and size of pollen from the originating individual rather than how much was transferred to heterospecific stigma, as would be needed in a basic assessment of potential allelopathic interactions. 

Sample number Depth (m) Abundance of pollen (grain g 1) Total abundance of sporopollen (grain g )... 

Dust pollen grains of a plant of your interest on the medium by using forceps, and seal the dish. Pollen grains soon hydrate and begin to extrude a tube. Pollen tubes usually grow well between 20°C and 30°C. Pollen tubes of Torenia grow at a maximum rate of approximately 600 pm/h in vitro. 

Brewbaker JL. The distribution and phylogenetic significance of binucleate and tri-nucleate pollen grains in the angiosperms. Am JBot 1967 54 1069-1083. 

Note that in some instances, spores and pollen grains can be air-dried and mounted onto stubs. 

Demanet CM, Sankar KV. Atomic force microscopy images of a pollen grain A preliminary study. S Afr JBot 1996 62 221—223. 

VanDerWelNN, PutmanCAJ, VanNoort SJT, DegrothBG, EmonsAMC. Atomic force microscopy of pollen grains, cellulose microfibrils and protoplasts. Protoplasma 1996 194 29-39. 

Pollen grains of another species, parthenium (Parthenium hysterophorus L.), contained growth inhibitors which inhibited fruit set in many test species (Sukhada and Jayachandra 1980). However this plant is a noxious weed and its pollen is strong, therefore use of parthenium in agriculture is unlikely. 

The main advantage of pollen allelopathy is that allelochemicals occur in a natural form, i.e., pollen grains and are biologically active at low doses (10 grains mm-2 on stigmas) (Murphy 2001). hi case of pollen allelopathy, autotoxicity was not established (Murphy and Aarssen 1995a). 

Transactions between plants and pollinators go back millions of years and vary greatly from species to species, but they all have certain features in common. A plant s goal is to coax pollinators to call upon its flowers, so the animal can both pick up local pollen grains and leave pollen it has brought from afar. To attract attention, plants advertise their presence with color and fragrance. Taking advantage of pollinators color vision, their flowers have... 

Cycads pollination by insects may be one of the earliest forms of insect-pollination. Like conifers, cycads bear their reproductive cells in cones rather than flowers. Individual cycad plants are either male or female, male plants having pollen cones and female plants, seed cones. Fertilization requires transfer of pollen grains from pollen cones to seed cones. The role of insects in this process has received attention in a cycad commonly known as the cardboard palm (Zamia furfuracea). This is a handsome horticultural plant with... 

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