Phylogeny and floral hosts of a predominantly pollen generalist group of mason bees (Megachilidae: Osmiini)

Within the genus Osmia, the three subgenera Osmia, Monosmia, and Orientosmia form a closely‐related group of predominantly pollen generalist (‘polylectic’) mason bees. Despite the great scientific and economic interest in several species of this clade, which are promoted commercially for orchard pollination, their phylogenetic relationships remain poorly understood. We inferred the phylogeny of 21 Osmia species belonging to this clade by applying Bayesian and maximum likelihood methods based on five genes and morphology. Because our results revealed paraphyly of the largest subgenus (Osmia s.s.), we synonymized Monosmia and Orientosmia under Osmia s.s. Microscopical analysis of female pollen loads revealed that five species are specialized (‘oligolectic’) on Fabaceae or Boraginaceae, whereas the remaining species are polylectic, harvesting pollen from up to 19 plant families. Polylecty appears to be the ancestral state, with oligolectic lineages having evolved twice independently. Among the polylectic species, several intriguing patterns of host plant use were found, suggesting that host plant choice of these bees is constrained to different degrees and governed by flower morphology, pollen chemistry or nectar availability, thus supporting previous findings on predominantly oligolectic clades of bees. © 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 111 , 78–91.     

Phylogenetic analysis of Aedes species distributed in Taif Province,Saudi Arabia,based on mitochondrial COX1 sequences

As Aedes mosquitoes are the predominant carriers of arboviruses responsible for global dengue fever and chikungunya outbreaks, understanding their genetic diversity and population structure can enhance dengue prevention and vector control efforts. Although sympatric cryptic species have been acknowledged in Aedes species subgroups in Southeast Asia, little information is available regarding the occurrence and dispersal of cryptic Aedes species in Saudi Arabia. In the present investigation, we intend to analyze genetic variations and perform a phylogenetic study of sympatric Aedes samples collected from various locations in Taif Province, Saudi Arabia. The locus of mitochondrial DNA cytochrome c oxidase subunit 1 (COX1, analyzed with DNA barcoding) was utilized to determine genetic variance and to build phylogenetic trees. For species identification, the COX1 sequences of Aedes samples from Taif Province were compared with those of Aedes samples from GenBank (National Center for Biotechnology Information, NCBI). To identify phylogenetic relationships and genetic variability, phylogenetic trees were created using Taif Province samples, GenBank A. albopictus samples, and GenBank A. aegypti samples. The phylogenetic analysis revealed that some Taif samples (A3, A7, F2, F4, F1, A4, A1, F9 and F6) were closer to A. aegypti and A. albopictus samples from Africa and East Asia, especially Kenya and Malaysia. Whereas other samples (F9, F6, A4, F1 and A1) were closer to the GenBank A. aegypti samples KP843383 (Thailand), HM399357(Australia), MK533632 (Kenya), KX420460 (Kenya), KU495081 (Australia) and MF179160 (China) than the remaining Taif samples. Overall, our findings demonstrate that examining the genetic diversity and phylogenetic linkages of Aedes samples can aid in understanding the evolution of Aedes cryptic species in the western regions of Saudi Arabia.     

甲醛诱导Tau蛋白形成“孔道样”聚集结构

尽管Lin等(University of California, Santa Barbara)就蛋白构象病中细胞死亡的机制提出了“非特异性淀粉样离子通道”(aspecific amyloid ion channels)学说,但到目前为止,尚未发现神经Tau蛋白能形成“孔道样”聚集结构,也未寻找到可以导致蛋白质形成“孔道样”聚集结构的诱导剂．依据本实验室提出的“散发性老年痴呆发生发展中的内源性甲醛慢性损伤”假说,采用一定浓度的甲醛与Tau蛋白进行温育,观察到甲醛可以明显诱导Tau蛋白分子聚集并形成淀粉样沉积物,同时也观察到了Tau蛋白“孔道样”聚集结构．上述结果为探索甲醛诱导Tau蛋白错误折叠形成的产物导致细胞代谢障碍和死亡的机制提供了新的研究思路．     

Raman microspectroscopy reveals long‐term extracellular activity of chlamydiae

The phylum Chlamydiae consists exclusively of obligate intracellular bacteria. Some of them are formidable pathogens of humans, while others occur as symbionts of amoebae. These genetically intractable bacteria possess a developmental cycle consisting of replicative reticulate bodies and infectious elementary bodies, which are believed to be physiologically inactive. Confocal Raman microspectroscopy was applied to differentiate between reticulate bodies and elementary bodies of Protochlamydia amoebophila and to demonstrate in situ the labelling of this amoeba symbiont after addition of isotope‐labelled phenylalanine. Unexpectedly, uptake of this amino acid was also observed for both developmental stages for up to 3 weeks, if incubated extracellularly with labelled phenylalanine, and P. amoebophila remained infective during this period. Furthermore, P. amoebophila energizes its membrane and performs protein synthesis outside of its host. Importantly, amino acid uptake and protein synthesis after extended extracellular incubation could also be demonstrated for the human pathogen Chlamydia trachomatis, which synthesizes stress‐related proteins under these conditions as shown by 2‐D gel electrophoresis and MALDI‐TOF/TOF mass spectrometry. These findings change our perception of chlamydial biology and reveal that host‐free analyses possess a previously not recognized potential for direct experimental access to these elusive microorganisms.     

Shoot regeneration and free-radical scavenging activity in <Emphasis Type="Italic">Silybum marianum</Emphasis> L.

The morphogenic potential and free-radical scavenging activity of the medicinal plant, Silybum marianum L. (milk thistle) were investigated. Callus development and shoot organogenesis were induced from leaf explants of wild-grown plants incubated on media supplemented with different plant growth regulators (PGRs). The highest frequency of callus induction was observed on explants incubated on Murashige and Skoog (MS) medium supplemented with 5.0 mg l⁻¹ 6-benzyladenine (BA) after 20 days of culture. Subsequent transfer of callogenic explants onto MS medium supplemented with 2.0 mg l⁻¹ gibberellic acid (GA₃) and 1.0 mg l⁻¹ α-naphthaleneacetic acid (NAA) resulted in 25.5 ± 2.0 shoots per culture flask after 30 days following culture. Moreover, when shoots were transferred to an elongation medium, the longest shoots were observed on MS medium supplemented with 0.5 mg l⁻¹ BA and 1.0 mg l⁻¹ NAA, and these shoots were rooted on a PGR-free MS basal medium. Assay of antioxidant activity of in vitro and in vivo grown tissues revealed that significantly higher antioxidant activity was observed in callus than all other regenerated tissues and wild-grown plants.     

Generic delivery of payload of nanoparticles intracellularly via hybrid polymer capsules for bioimaging applications

Towards the goal of development of a generic nanomaterial delivery system and delivery of the 'as prepared' nanoparticles without 'further surface modification' in a generic way, we have fabricated a hybrid polymer capsule as a delivery vehicle in which nanoparticles are loaded within their cavity. To this end, a generic approach to prepare nanomaterials-loaded polyelectrolyte multilayered (PEM) capsules has been reported, where polystyrene sulfonate (PSS)/polyallylamine hydrochloride (PAH) polymer capsules were employed as nano/microreactors to synthesize variety of nanomaterials (metal nanoparticles; lanthanide doped inorganic nanoparticles; gadolinium based nanoparticles, cadmium based nanoparticles; different shapes of nanoparticles; co-loading of two types of nanoparticles) in their hollow cavity. These nanoparticles-loaded capsules were employed to demonstrate generic delivery of payload of nanoparticles intracellularly (HeLa cells), without the need of individual nanoparticle surface modification. Validation of intracellular internalization of nanoparticles-loaded capsules by HeLa cells was ascertained by confocal laser scanning microscopy. The green emission from Tb(3+) was observed after internalization of LaF(3):Tb(3+)(5%) nanoparticles-loaded capsules by HeLa cells, which suggests that nanoparticles in hybrid capsules retain their functionality within the cells. In vitro cytotoxicity studies of these nanoparticles-loaded capsules showed less/no cytotoxicity in comparison to blank capsules or untreated cells, thus offering a way of evading direct contact of nanoparticles with cells because of the presence of biocompatible polymeric shell of capsules. The proposed hybrid delivery system can be potentially developed to avoid a series of biological barriers and deliver multiple cargoes (both simultaneous and individual delivery) without the need of individual cargo design/modification.     

Establishment of a complete series of a monosomic tomato chromosome addition lines in the cultivated potato using RFLP and GISH analyses

With the aim of establishing a complete monosomic alien tomato chromosome addition series in a potato background, the backcross progenies derived from repeated crossing of potato (+) tomato fusion hybrids to potato were screened through RFLP and GISH analyses. Because of the availability from our previous work of seven of the possible 12 tomato monosomic additions, selected from BC₂ populations, attention was paid to those alien additions that were missing. Thus, since the alien additions were already available for tomato chromosomes 1, 2, 4, 6, 8, 10 and 12, efforts were made to select for chromosomes 3, 5, 7, 9 and 11 by screening specific BC₃ populations. In all, 105 plants from four BC₃ populations were screened through a combination of RFLP and GISH analyses in order to complete the series. Among the newly selected alien addition lines, five were monosomic additions for all the remaining chromosomes and one was a disomic addition for chromosome 11. When using conventional cytogenetics the selection of monosomic alien additions is highly laborious. All the tomato chromosomes showed a variable rate of transmission. Chromosome 6 was transmitted at 29.6% and 81.5% frequency in populations 2705 and 2701 respectively. The present study showed that molecular markers and molecular cytogenetics applied in this study were most efficient and rapid because a pre-selection for the desired genotypes was possible by screening a population with chromosome-specific markers for the presence of one tomato chromosome at a time. Received: 9 January 2001 / Accepted: 26 January 2001