A new species of Golunda (Rodentia, Muridae) from the Late Pleistocene of Indian Himalaya

The youngest fossil Golunda (Rodentia, Muridae) is described from the Late Pleistocene fluvio-lacustrine deposits, exposed at Dulam (Bageshwar), Kumaun Lesser Himalaya, India. The age of fossiliferrous horizon is estimated as 31,000 yr BP. A new species, Golunda dulamensis nov. sp. has highly derived characters, e.g., antero-posteriorly stretched molars, upper molars with more length and less width, stephanodonty, cusps in M₃ strongly inclined backward giving the molars a very stretched aspect, and metaconid and entoconid in M₃ forming almost straight lingual row of the cusps. G. dulamensis nov. sp. is most similar to present day G. ellioti but differs from the later slightly by larger size, a thin connection between t₄ and t₅ in M¹, and comparatively larger entoconid and very weakly developed antero-labial cusp in M₃. We suggest that highly specialized molars of G. dulamensis nov. sp. and present day G. ellioti are derivable through G. kelleri. We also propose that Golunda migrated from Asia to Africa, not from Africa to Asia as was thought by earlier workers.     

Taphonomy and compositional fidelity of Quaternary fossil assemblages of terrestrial gastropods from carbonate-rich environments of the Canary Islands

Quaternary aeolian deposits of the Canary Islands contain well‐preserved terrestrial gastropods, providing a suitable setting for assessing the taphonomy and compositional fidelity of their fossil record over ~13 kyr. Nine beds (12, 513 shells) have been analysed in terms of multivariate taphonomic and palaeoecological variables, taxonomic composition, and the stratigraphic and palaeontological context. Shells are affected by carbonate coatings, colour loss and fragmentation. Shell preservation is size‐specific: juveniles are less fragmented and show colour preservation more commonly than adults. In palaeosols, the adult shell density correlates negatively with the proportion of fragmented adults, negatively with the proportion of juveniles, and positively with the proportion of adults with coatings. High bioturbation intensity in palaeosols is associated with low shell fragmentation and high proportion of shells with coatings. These relationships imply that high adult density in palaeosols was driven by an increase in shell production rate (related to a decrease in predation rates on adults and a decrease in juvenile mortality) and a decrease in shell destruction rate (related to an increase in durability enhanced by carbonate precipitation). In dunes, the relationships between taphonomic alteration, shell density and bioturbation are insignificant. However, dune assemblages are characterized by a lower frequency of shells with coatings and higher rates of colour loss, indicating lower shell durability in dunes than in palaeosols. Additionally, non‐random differences in the coating proportion among palaeosols imply substantial temporal variation in the rate of carbonate crust formation, reflecting long‐term changes in bioturbation intensity that covaries positively with shell preservation. Dunes and palaeosols do not differ in species abundances despite differences in the degree of shell alteration, suggesting that both weakly and strongly altered assemblages offer data with a high compositional fidelity. Carbonate‐rich terrestrial deposits originating in arid conditions can enhance the preservation of gastropods and result in fossil assemblages that are suitable for palaeoecological and palaeoenvironmental studies of terrestrial ecosystems.     

周口店遗址保护地区地质—地球物理调查简报及结果解释

1996年9月,法国地球物理学家与中国有关科研人员联合对周口店古人类遗址保护区进行了系统的地球物理调查,发现了多处异常带,尤其是在地质和地球物理异常带交汇（或重叠）处,这些异常部位是最有可能的第四纪堆积物潜在处,值得进一步勘探,这样的区域总共有5个。但经过分析,个别异常区的第四纪堆积与后来的人类活动有关。     

Comparative molecular biological analysis of the microbial community of the Holocene and Pleistocene deposits of Posol’skaya Shoal,Lake Baikal

The bacterial diversity was studied in sediment layers of Posol’skaya Shoal station (Southern Baikal) belonging to different periods. A set of primers specific to individual bacterial groups was used to analyze the 16S rRNA gene fragments. The bacterial diversity in the Holocene deposits was found to be higher than in the Pleistocene ones. In the upper sediments, a positive PCR reaction with bacterial primers and with specific cyanobacterial and archaebacterial primers was detected. The following phylogenetic groups were revealed in the microbial community of the surface horizon: green nonsulfur bacteria, δ-proteobacteria, β-proteobacteria (Nitrospirae), α-proteobacteria, acidobacteria, crenarchaeota, euryarchaeota, and groups of uncultured bacteria. From the DNA of the Pleistocene deposits, the PCR product was obtained only with bacterial primers. The representatives of the genus Pseudomonas were most closely related to the sequences obtained (95–97% homology).     

Subcellular localization of cadmium in roots and leaves of Arabidopsis thaliana

We examined the subcellular cadmium (Cd) localization in roots and leaves of wild-type Arabidopsis thaliana (ecotype Columbia) exposed to environmentally relevant Cd concentrations. Energy-dispersive X-ray microanalysis (EDXMA) was performed on high-pressure frozen and freeze-substituted tissues. In the root cortex, Cd was associated with phosphorus (Cd/P) in the apoplast and sulfur (Cd/S) in the symplast, suggesting phosphate and phytochelatin sequestration, respectively. In the endodermis, sequestration of Cd/S was present as fine granular deposits in the vacuole and as large granular deposits in the cytoplasm. In the central cylinder, symplastic accumulation followed a distinct pattern illustrating the importance of passage cells for the uptake of Cd. In the apoplast, a shift of Cd/S granular deposits from the middle lamella towards the plasmalemma was observed. Large amounts of precipitated Cd in the phloem suggest retranslocation from the shoot. In leaves, Cd was detected in tracheids but not in the mesophyll tissue. Extensive symplastic and apoplastic sequestration in the root parenchyma combined with retranslocation via the phloem confirms the excluder strategy of Arabidopsis thaliana.     

In deep water: a crinoid–brachiopod association in the Upper Oligocene of Antigua,West Indies

Extant brachiopods and stalked crinoids are found together in the deeper waters of the Caribbean Sea. Analogous brachiopod/crinoid associations have been reported from diverse palaeoenvironments in the Neogene of the region. Studied examples include the Pleistocene of Jamaica (deeper water fore reef), and the Miocene of Jamaica (island slope chalks), Barbados (accretionary prism) and Carriacou (turbiditic siliciclastic shelf). Comparison with analogous modern environments indicates deposition in 150+m water depth. This association has now been extended back into the Late Oligocene. Crinoids and brachiopods both occur in the Antigua Formation of Antigua; both occur high in the formation, implying deeper water in this retrograde succession. They have received little attention from systematists, although the brachiopods Cistellarcula dubia Cooper and Tichosina foresti Cooper have previously been described from the Antigua Formation; to these, we add Cistellarcula sp., Argyrotheca sp. and Tichosina sp. At Half Moon Bay in southeast Antigua, high in the Antigua Formation, we have found columnals of isocrinid crinoids (cf. Isocrinus sp.) associated with rare brachiopods (Terebratulina sp.) in island slope deposits. These taxa provide independent evidence for the deeper water aspect of this part of the Antigua Formation, in beds that also yield large, thin‐walled fossil sponges.     

论南京直立人化石的年代

根据南京直立人洞穴钙板方解石的ＴＩＭＳ测年,南京直立人化石的年代应早于距今５０万年。南京猿人洞穴堆积所含哺乳动物化石和孢粉分析,表明含人类化石的堆积形成于冷期;哺乳动物化石的比较分析和聚类分析认为含南京直立人化石层可对比于北京猿人洞穴堆积的第６层和深海岩芯氧同位素记录的１４阶段,从而进一步支持南京直立人化石时代早于５０万年的Ｔ＾ＩＭＳ测年结果。     

昆明盐矿古老岩盐沉积中可培养细菌多样性研究

为了了解昆明盐矿古老岩盐沉积中可培养细菌的多样性,用MBA和ISP2分离和培养了昆明盐矿卤水和盐晶中的细菌44株。发现盐晶中的可培养好氧细胞数量(3·1×103~3·7×106CFU/g)远远高于卤水中的数量(1·3~6·3×103CFU/L)。分离所得纯培养物的16SrDNA序列系统发育分析结果表明,44株菌可分为4大类群34个不同的分类单元(16SrDNA序列相似性大于97%为同一分类单元)。24株属于厚壁菌门(Firmicutes,54·6%),2株属于变形菌门α亚群(α-Proterbacteria,4·6%),4株属于变形菌门γ亚群(γ-Proterbacteria,9·1%),14株属于放线细菌门(Actinobacteria,31·7%)。卤水和盐晶中的优势菌都是Bacillus属菌(26·1%和59·9%)。据16SrDNA序列相似性分析发现7株菌为可能的新种或属。此外,还筛选到7株抗菌活性菌株。研究表明,昆明盐矿古老岩盐沉积中,不仅含有较为丰富的微生物物种多样性,并且存在许多未被认识的新物种和生物活性菌株,为古老岩盐沉积中微生物的深入研究奠定了基础。     

大气降尘沉积对塔克拉玛干沙漠腹地土壤水盐运移的影响

利用微型蒸渗仪(MLS)对不同粒级和不同厚度大气降尘沉积条件下塔克拉玛干沙漠腹地土壤水分蒸发和盐分运移进行了模拟试验.结果表明：不同粒级和不同厚度大气降尘沉积均对研究区土壤水分蒸发和盐分运移有显著影响;在相同的沉积厚度和相同的初始含水量条件下,细粒物质（粒径<0.063 mm）沉积可促进土体蒸发、加速下层土体的干旱和盐分的表聚,而粗粒物质（粒径0.063～2 mm）沉积则抑制了土壤水分蒸发、降低了深层土壤水分的损失和盐分的表聚;研究区土壤水分蒸发抑制效率在0.20 mm粒径处出现拐点,粒径在0.063～0.20 mm时,蒸发抑制效率随粒径增大而增大,当粒径>0.20 mm时,蒸发抑制效率则随粒径增大而减小.在相同粒级和相同的初始含水量条件下,不同厚度大气降尘沉积对土壤水分蒸发具有抑制作用,且土壤水分蒸发抑制效率随着沉积厚度的增大而增大,蒸发抑制效率与沉积厚度呈对数关系;沉积厚度越大,盐分向表层积聚越困难.降尘的加入可能导致干旱荒漠区生态系统的不稳定.     

Proflavine derivatives as fluorescent imaging agents of amyloid deposits

A series of proflavine derivatives for use to further image Aβ amyloid deposits were synthesized and characterized. Aged 3xTg-AD (23 months old) mice hippocampus sections incubated with these derivatives revealed preferential labeling of amyloid plaques. Furthermore an in vitro binding study showed an inhibitory effect, although moderate, of these compounds on Aβ₄₀ fibril formation. This study highlights the potential of proflavine as a molecular scaffold for designing new Aβ imaging agents, its native fluorescence allowing in vitro neuropathological staining in AD damaged brain sections.