依据Altingiaceae和Juglandaceae孢粉化石探讨我国第三纪植物群及气候特征

依据化石花粉Caryapollenites和Liquidambarpollenites的现存对应植物的生态特征 ,探讨我国第三纪一些孢粉组合的植物群及其所反映的古气候特征。得出 :1)我国第三纪植被 ,从第三纪初至末 ,东西部就有明显区别 ;2 )我国第三纪的孢粉组合所反映的古植被可以和我国现存的植被进行比较 ,从而获得气候特征 ;3)从孢粉资料判断 ,Carya属和Altingiaceae科植物从第三纪初至今 ,生长地带纬向南移了 10°多。     

Challenges in estimating past plant diversity from fossil pollen data: statistical assessment, problems, and possible solutions

Fossil pollen data from sediment cores may be used as a measure for past plant diversity. According to the theory of probability, palynological richness is positively related to the pollen count. In a low pollen count, only common taxa are detected, whereas rare taxa are only detected by chance. The detection of all pollen taxa requires a very high pollen count, which is time-consuming. In regular palynological investigations, the detected richness in pollen spectra varies with the pollen count. Rarefaction analysis estimates palynological richness in an exactly equal-sum count for all samples, so that comparison between samples is meaningful. However, the over-representation of some taxa suppresses the detection probability of rare taxa; low total pollen abundance in a sample enhances the detection probability of rare taxa and long-distance transported pollen grains. These factors bias the observed palynological richness and distort comparisons. Palynological richness in a pollen count proportional to its pollen influx may be one proxy for reconstructing diversity trends through time. The use of this proxy overcomes most problems encountered in rarefaction analysis, but is constrained by inaccuracy in estimating pollen influx due to the imprecise time control of sediment cores. Estimating palynological richness by mathematical methods may be another way of reconstructing pollen diversity. Pollen data tend to reflect diversity on a regional scale. Sites from small basins have the advantage of recording diversity at both local and regional scales, if the detection of each taxon is independent. By associating one site from a large basin with a series of sites from very small basins (e.g. forest-hollows), information about both regional and local diversity may be obtained. Entomophilous pollen taxa may have to be measured using a different strategy than anemophilous taxa.     

Why is pollen yellow? And why are there so many species in the tropical rain forest?

Pollen appears to need protection from UV‐B insolation, and some protection is provided by yellow flavonoids and some other compounds. UV‐B insolation is mutagenic and could thus provide the mutations needed for speciation. Tropical montane vegetation experiences the highest UV‐B insolation of any vegetation in the world. This will be enhanced by volcanic eruptions releasing aerosols. There is evidence of strong volcanicity and mutation in Permian times, when world vegetation changed dramatically. Palynological richness, used as a measure of palaeo‐biodiversity, shows rapid increases in the Palaeo‐Eocene and Early Miocene, both times of peak temperature. DNA evidence suggests increasing diversity at these times. Milankovitch cycles at these times would have caused vertical migrations of tree taxa, with magnitudes of c. 800 m. These migrations could have led to isolation of populations on mountain peaks, allowing allopatric speciation, especially in the montane elevated UV‐B environment. This process, when repeated, could have led to a ‘species pump’, and thus to higher biodiversity.     

Sclerites and possible mouthparts of Wiwaxia from the temperate palaeolatitudes of Colombia,South America

The problematic mollusc Wiwaxia is perhaps the most widely distributed non‐mineralized Cambrian metazoan, but has only been reported from palaeotropical latitudes. Here, we describe mid‐Cambrian (Drumian, c. 504 Ma) sclerites and possible tooth arrays from the northern Llanos Basin, Colombia, recovered from drilled ditch cuttings by palynological processing – demonstrating that pristine material and low‐manipulation processing are not essential to the recovery of Small Carbonaceous Fossils. This, the first report of Wiwaxia from South America, substantially expands Wiwaxia's geographic range into the high palaeolatitudes.     

模糊数学在孢粉分带上的应用

笔者在研究新疆准噶尔盆地西北缘百３８井克拉玛依组粉组合时，运用模糊数学的方法进行了孢粉分带，本文介绍了进行孢粉分带所选用的数学公式，用ＢＡＳＩＣ语言所编制的计算程序以及使用方法。     

Confusing concepts in Lateglacial stratigraphy and geochronology: origin, consequences, conclusions (with special emphasis on the type locality Bøllingsø)

A great confusion currently exists on the stratigraphic and geochronologic subdivision of the Weichselian Lateglacial. This paper unravels the development of this confusion, which is interpreted to be mainly due to a combination of wrongly used stratigraphical concepts, incorrect interpretations, and erroneous correlation between various sites and records. Special emphasis is laid on the palynological methods of Johs. Iversen and on the type locality Bøllingsø, from which the original (partly previously unpublished) data are presented and evaluated. It is concluded that almost all stratigraphic schemes and terms have lost their original value.     

A critical assessment of standard processing methods for the preparation of palynological samples

Standard processing techniques for the isolation of organic walled dinoflagellate cysts from geological samples are examined, with particular attention to the size and type of sieve mesh used. Variations within the ‘standard’ processing techniques used by different laboratories are identified, and an assessment of the retention capacities of meshes of different sizes and different materials is carried out. Some dinoflagellate cysts and large numbers of Lycopodium spores, used for the calculations of absolute abundance data, were found to pass through 20 μm meshes. This is due to a combination of factors including: the diagonal aperture diameter of a 20 μm mesh measuring over 28 μm; the three-dimensional properties of different mesh weaves (nylon and polyester); and the non-spherical shape of the particles. Experiments demonstrate that the maximum mesh size that should be used in palynological processing is 15 μm. Nylon mesh is more practical to use than polyester as processing time is reduced, but nylon is degraded by contact with acid solutions. Meshes with apertures < 15 μm may be used, though this may be impractical for large samples containing significant quantities of fine siliciclastic or organic material.     

对Batten和Morrison(1983)过滤孢粉残渣方法的实验检测及评价

Batten和Morrison(1983)介绍了一种用砂芯漏斗过滤孢粉残渣的方法,其主要目的是为了适合孢粉相研究的需要,避免用过筛的方法导致将所有＜10μm的颗粒都清除掉的缺点,同时它也兼具快速、经济的优点.但是这种方法可能会导致一定的化石损失.为了确切地了解损失量的大小,同时也为了对国内同类漏斗产品进行选择,我们对国内生产的2种型号的漏斗及Batten和Morrison使用的P100漏斗进行了实验检测和比较.结果显示,P50漏斗的化石损失很少且主要限于15 μm左右大小的成分.P100和P70可能会导致略高的化石损失,滤过颗粒的粒径可以更大.但是,这种损失可以通过对滤过物用10μm的筛网过滤收集的便捷方法得以补救.     

Viola umphangensis (Violaceae), a new species from Thailand

Viola umphangensis S. Nansai, Srisanga & Suwanph., a new species from Thailand, is described and illustrated. Morphological, anatomical and palynological characters of V. umphangensis are compared with a similar species, V. betonicifolia Sm. An amended key to the Viola species in the Flora of Thailand account is provided.     

Phenolics from Chilean Bee Bread Exhibit Antioxidant and Antibacterial Properties: The First Prospective Study

Bee bread (BB) is a beehive product generated upon fermentation of pollen combined with flower nectar and glandular secretions. The potential application of BB is related to its nutritional and functional components, including phenolic compounds. This is the first prospective study on palynological parameters, phenolics, antioxidant, and antibacterial activity of Chilean bee bread in vitro. The tested material exhibited high levels of phenolics (1340±186 mg GAE/100 g BB) and showed antioxidant capacity as determined by the FRAP (51±2 μmol Trolox equivalent/g BB) and ORAC-FL (643±64 μmol Trolox equivalent/g BB) and antibacterial activity against Streptococcus pyogenes. Furthermore, the phenolic acids and flavonoids was determined using liquid chromatography-mass spectrometry, and the concentration was determined using liquid chromatography with diode array detection. Kaempferol, quercetin, ferulic acid, and rutin were the main phenolics found. This study demonstrates the bioactive potential of Chilean BB and supports the evidence that this bee product is a promising source of antioxidants and antimicrobial compounds.