Pollen samples

Procedure of pollen preparation Pollen can be washed off stigmas with an acetone solution as water or other polar solutions often fail to sufficiently break electrostatic bonds holding heterospecific pollen to stigma. However, this means the acetone must be evaporated in an air drying oven (48 h) because a Coulter Counter requires a saline solution of standard volume (usually 10-20 ml) be used to prepare pollen samples. If the solutions are mixed and the volumes are inconsistent, there is a risk that differences in conductivity will create errors. 

Pollen consists of reproductive cells released by plants (and sometimes carried by insects) at certain times of the year. Individual species of plant are identifiable by the grains of pollen they generate. Klaus Oeggl of Innsbruck University, James H. Dickson at the University of Glasgow in Scotland, and their colleagues have studied pollen samples obtained from Otzi s digestive tract. Some of this pollen may have been eaten intentionally, but Otzi probably swallowed most of it accidentally, either in the course of eating a meal or by inhalation. 

Current pollen detection and warning systems are based solely on morphological information. Pollen samples are deposited from the air, pretreated, and then analysed microscopically. The method works well, but it can be slow. Our research is directed towards the development of a fast automated on-line detection of pollen species based on Raman spectral fingerprints. The Raman spectra are treated as patterns that can be recognized by identification algorithms, which are more objective and less time-consuming than mere visual inspection. 

Our first objective was to determine whether microencapsulated methyl parathion Is unique In Its property to be carried back to the hive by bees. To that end a mixture of three commonly used insecticides along with MMP was applied to a plot of blooming rape. The agents were azlnphos-methyl (Guthlon), parathion, and carbaryl (Sevin). By using a mixture on a single plot the effects of variation In bee visitation were eliminated and the tendencies to be carried to the hive could be measured by the relative residue levels in the pollen samples. Five applications were made over a period of seventeen days. Pollen samples were collected from hives placed near the field after two, three, four, and five successive applications approximately two days after each application was made. The application rates were doubled for the last two applications. The data are shown In Table I. 

Negri, G., Teixeira, E.W. Alves, M.L.U.T.M. F Moreti, A.C.C.C. Otsuk, I.P. Borguini, R.G. Salatinoz, A. 2011. Hydroxyciimamic acid amide derivatives, phenolic compounds and antioxidant activities of extracts of pollen samples from southeast Brazil. J. Agric. Food Chem. 59 5516-5522. 

In the city of Modena, the levels of lead, chromium, nickel, and cadmium in the air (as measured by automatic detectors) were compared with those contained in honey, larvae, and pollen samples taken monthly from beehives situated in the vicinity of the detectors themselves. The findings cannot be considered conclusive, as the average monthly data recorded by the automatic detectors referred to a single point in the atmosphere whereas the beehive data were referable to the area around the hive visited by bees in a given month. Nonetheless, they showed that the fresh honey recently imported into the honey chamber was the matrix that best reflected the trend in lead contamination of the atmosphere, as recorded by the detectors [89]. It was also observed, again with regard to lead in the honey matrix, that the values provided by the detectors were a reliable anticipation of the biological data. In the same study, the authors also tried to estimate the ratio of the mean concentration of the various contaminants in honey (in Jig/kg) and that in the air (in pg/m ), which may be estimated as approximately 1000-2000 for lead and nickel, 2000-4000 for chromium, and 3000-5000 for cadmium [90]. 

We performed a series of replicated bioassays using bodi purified toxins and pollen samples from a number of com hybrids created widi different transformation events. In these, we measured the effect of increasing doses of Bt pollen on feeding behavior and weight gain of first-instar monarch larvae. We established a no-observable-effect level (NOEL) from these results and compared that dose with the density of pollen that we estimated to occur on milkweed leaves in and around com fields to determine the likelihood of encounter with an effective dose. To validate our laboratory observations and estimates of intact, we performed a series of field experiments over two years in tiuee different locations within the Com Belt. Monarch larvae were eitiier caged on milkweed plants or fed milkweed leaves from plants in and around com fields... 

Analysis of pollen in deposits filling depressions on landslides can yield both an estimated age of initial movement and, in some cases, a movement history through time. Such analyses assume that sediment deposition and incorporation of pollen occur immediately following landslide movement and that local climatic and vegetation variations can be accounted for. Pollen samples from the buried ground surface beneath the toes of landslides also have potential for use in dating landslide movement. 

Maggi, V. 1994. Evaluation of the Dietary Effect(s) of Transgenic Bt Maize (Corn) Pollen (Sample PH0176-0294) on Honeybee Development Lab Project Number CAR 176-94. Unpublished study prepared by California Agricultural Research, Inc. 57 p. 

SWS are useful to obtain direct indications of hydrocarbons (under UV light) and to differentiate between oil and gas. The technique is applied extensively to sample microfossils and pollen for stratigraphic analysis (age dating, correlation, depositional environment). Qualitative inspection of porosity is possible, but very often the sampling process results in a severe crushing of the sample thus obscuring the true porosity and permeability. 

Samen-haar, n. (Bot.) seed hair, coma, -hefe, /. seed yeaat. -keim, m. germ, embryo, -kem, m. seed kernel (Bot.) endosperm Physiol.) spermatic nucleus, -lappen, m. seed lobe, cotyledon, -ol, n. seed oil. -pflan-zen, /.pi. seed plants, Spermatophyta. -probe, /. seed test or sample, -saift, m. seminal fluid, -staub, m. pollen, -tierchen, n. sp< rmatozoon. -zelle, /. seminal cell, spertpatozoon. -zucker, m. quercitol, quer-cite. ... 

By number count the great majority of particles in the outside air are likely to be less than 1 pm. By weight, these small particles will account for a very small proportion of the sample. A filter with a high efficiency measured by weight of particles trapped may be almost transparent to the small ones. Very high counts can be found in rural areas from pollen or agricultural activities. 

Each plant tissue tends to have an obviously distinctive profile of flavonoids. The flavonoid content can reach about 0.5% in pollen, 10% in propolis, and about 6 mg/kg in honey. Havonoid aglycones appear to be present only in propolis and honey, while pollen contains flavanols in herosidic forms. The flavonoids in honey and propolis have been identified as flavanones and flavanones/flavanols (Campos et ah, 1990). The antimi-crobially active flavanone pinocembrine was foimd to be a major flavonoid in honey (Bogdanov, 1989). Amiot et ah (1989) studied two blossom and two honeydew Swiss honey samples and foimd that pinocembrine was the main flavonoid. Pinocembrine concentration varied between 2 and 3 mg/kg (Bogdanov, 1989). Berahia et ah (1993) analyzed sunflower honey samples and detected six flavone/flavols, four flavanone/ flavols, and pinocembrin, of which pinocembrin is the main flavonoid. The flavonoids in sunflower honey and propolis were characterized and assessed for their effects on hepatic drug-metabolizing enzymes and benzo [fl]pyrene-DNA adduct formation (Sabatier et ah, 1992 Siess et ah, 1996). 

Another perplexing problem that has often been encountered is the determination of highly potent compounds which are usually present in minute amounts. They may be masked by other chemicals whose physical/chemical (chromatographic) properties are so similar that they may be very difficult to track down with limited quantities of plant samples. This type of situation is not uncommon in plant sciences and a typical example is our recent isolation of brassino-lide fran rape (Brassica napus L.) pollen (52). 

Observations Observation on each test sample on pollen lasts from 2 -24 h (fresh microspores, < 1 month after collection) to 6-24 h (microspores stored > 1 month). 

Fig. 2 Relative effects of rhamnetin, isorhamnetin and total extract from pollen of Phleum pratense on in vitro germination of pollen of Elytrigia repens. Data points are means and standard errors from 50 replicate samples.

---