Metabolic profiling in Echium plantagineum: presence of bioactive pyrrolizidine alkaloids and napthoquinones from accessions across southeastern Australia

Geographically distinct populations of Paterson’s curse (Echium plantagineum L., Boragineacea), found near roadsides across New South Wales and Victoria, Australia were surveyed along 3 distinct longitudinal transects in spring of 2011 for presence of pyrrolizidine alkaloids and naphthoquinones in sampled plants. Composite samples of shoots and roots were collected from each of 45 sites; shoot extracts were subjected to solid phase extraction and LC-ESI/MS for determination of pyrrolizidine alkaloids (PAs) and related N-oxides (PANOs), while root periderm extracts were analysed for naphthoquinone content spectrophotometrically and by LC-ESI/MS. Metabolic profiling of 12 possible PAs and PANOs showed their consistent appearance in all shoot extracts, with lepthamine N-oxide, echimidine-N oxide and echumine N-oxide predominant. The three major PANOs were significantly higher in northern sampling locations than those further south. Root extracts contained shikonin and several related naphthoquinones, as well as two of the major PANOs found in the leaves. Naphthoquinones were highest in the northwest corner of the sampled region. The patterns of abundance of secondary metabolites in E. plantagienum suggest that climate change might result in greater production of defensive compounds by E. plantagineum, making this weed increasingly toxic to livestock.     

Sinusoidal profiles of lactate dehydrogenase activity in rat liver

Lactate dehydrogenase activities were measured along two sinusoidal paths (1) between small portal tracts and central veins and (2) between regions of adjoining septal branches and central veins in the livers of male Wistar rats, using a Lowry technique. The established profiles of enzyme activity provide further support of functional heterogeneity of liver sinusoids and their abutting hepatocytes related to morphological differences of the sinusoidal bed. Within the hepatocytes a pronounced heterogeneity in enzyme activity was recorded surrounding small portal tracts and central veins. The lowest values of activity were determined in those cells located in close proximity to the vessels, which emphasizes their exceptional morphological and functional position.     

Gut microbiota composition is associated with environmental landscape in honey bees

There is growing recognition that the gut microbial community regulates a wide variety of important functions in its animal hosts, including host health. However, the complex interactions between gut microbes and environment are still unclear. Honey bees are ecologically and economically important pollinators that host a core gut microbial community that is thought to be constant across populations. Here, we examined whether the composition of the gut microbial community of honey bees is affected by the environmental landscape the bees are exposed to. We placed honey bee colonies reared under identical conditions in two main landscape types for 6 weeks: either oilseed rape farmland or agricultural farmland distant to fields of flowering oilseed rape. The gut bacterial communities of adult bees from the colonies were then characterized and compared based on amplicon sequencing of the 16S rRNA gene. While previous studies have delineated a characteristic core set of bacteria inhabiting the honey bee gut, our results suggest that the broad environment that bees are exposed to has some influence on the relative abundance of some members of that microbial community. This includes known dominant taxa thought to have functions in nutrition and health. Our results provide evidence for an influence of landscape exposure on honey bee microbial community and highlight the potential effect of exposure to different environmental parameters, such as forage type and neonicotinoid pesticides, on key honey bee gut bacteria. This work emphasizes the complexity of the relationship between the host, its gut bacteria, and the environment and identifies target microbial taxa for functional analyses.     

Marmoset phylogenetics, conservation perspectives, and evolution of the mtDNA control region

Marmosets (genus Callithrix) are a diverse group of platyrrhine primates with 13-15 purported taxa, many of them considered endangered. Morphological analyses constitute most of the basis for recognition of these forms as distinct taxa. The purpose of this study was to provide a molecular view, based on mitochondrial control region sequences, of the evolutionary history of the marmosets, concomitant with a molecular phylogenetic perspective on species diversity within the group. An additional purpose was to provide the first comparative examination of a complete New World monkey control region sequence with those of other mammals. The phylogenetic analyses provide convincing support for a split between the Atlantic forest and Amazonian marmosets, with the inclusion of the pygmy marmoset (Cebuella pygmaea) at the base of the Amazonian clade. The earliest branch of the Atlantic forest group was C. aurita. In the Amazonian group, the analyses do not support the recognition of C. humeralifer and the recently described C mauesi as distinct taxa. They do, however, support a clear distinction between C. argentata and a strongly supported mixed clade of C. humeralifer and C. mauesi. In the Atlantic forest group, the phylogenetic tree suggests mixing between C. penicillata, C. kuhli, and possibly C. jacchus. Most of the sequence features characteristic of other mammal control regions were also evident in marmosets, with the exception that conserved sequence blocks (CSBs) 2 and 3 were not clearly identifiable. Tandem repeat units often associated with heteroplasmy in a variety of other mammals were not evident in the marmoset sequences.      

Somatic embryo cycling: Evaluation of a novel transformation and assay system for seed-specific gene expression in soybean

Somatic embryo cycling, a modification of soybean somatic embryogenic suspension culture, was developed as an efficient and rapid method of producing tissue suitable for stable transformation of soybean germplasm by biolistic particle bombardment. Instead of using immature seed explants, cotyledon-staged somatic embryo hypocotyls were placed on auxin-containing medium, where they initiated new somatic embryos primarily from single epidermal cells. By bombarding hypocotyls prior to initiation of subsequent embryo formation, we have effectively transformed soybean somatic embryos with the reporter genes neomycin phosphotransferase,gb-glucuronidase, and a mammalian stearyl CoA delta-9 desaturase, controlled by a seed-specific promoter. These embryos contain significantly reduced levels of saturated palmitic and stearic fatty acids, and significant amounts of monounsaturated palmitoleic acid, which is not normally abundant in soybean seeds. This study demonstrates the effectiveness of somatic embryo cycling for soybean transformation, and for testing expression of genes for seed-specific proteins. Abnormal flower development in recovered plants is a limitation for application of the technique to produce transgenic seed at present.     

Phylogenetic Analysis of Heterothallic Neurospora Species

We examined the phylogenetic relationships among five heterothallic species of Neurospora using restriction fragment polymorphisms derived from cosmid probes and sequence data from the upstream regions of two genes, al-1 and frq. Distance, maximum likelihood, and parsimony trees derived from the data support the hypothesis that strains assigned to N. sitophila, N. discreta, and N. tetrasperma form respective monophyletic groups. Strains assigned to N. intermedia and N. crassa, however, did not form two respective monophyletic groups, consistent with a previous suggestion based on analysis of mitochondrial DNAs that N. crassa and N. intermedia may be incompletely resolved sister taxa. Trees derived from restriction fragments and the al-1 sequence position N. tetrasperma as the sister species of N. sitophila. None of the trees produced by our data supported a previous analysis of sequences in the region of the mating type idiomorph that grouped N. crassa and N. sitophila as sister taxa, as well as N. intermedia and N. tetrasperma as sister taxa. Moreover, sequences from al-1, frq, and the mating-type region produced different trees when analyzed separately. The lack of consensus obtained with different sequences could result from the sorting of ancestral polymorphism during speciation or gene flow across species boundaries, or both.     

BLUE WHALE VISUAL AND ACOUSTIC ENCOUNTER RATES IN THE SOUTHERN CALIFORNIA BIGHT

The relationship between blue whale ( Balaenoptera musculus ) visual and acoustic encounter rates was quantitatively evaluated using hourly counts of detected whales during shipboard surveys off southern California. Encounter rates were estimated using temporal, geographic, and weather variables within a generalized additive model framework. Visual encounters (2.06 animals/h, CV = 0.10) varied with subregion, Julian day, time of day, and year. Acoustic encounters of whales producing pulsed A and tonal B call sequences (song; 0.65 animals/h, CV = 0.06) varied by Julian day, survey mode (transit or stationary), and subregion, and encounters of whales producing downswept (D) calls (0.41 animals/h, CV = 0.09) varied by Julian day and the number of animals seen. Inclusion of Julian day in all models reflects the seasonal occurrence of blue whales off southern California; however, the seasonal peak in visual encounters and acoustic encounters of D calling whales (July–August) was offset from the peak in acoustic encounters of singing whales (August–September). The relationship between visual and acoustic encounter rates varied regionally, with significant differences in several northern regions. The number of whales heard D calling was positively related to the number of animals seen, whereas the number of singing whales was not related to visual encounter rate.     

SYNCHRONIZED GROWTH OF THALASSIOSIRA PSEUDONANA (BACILLARIOPHYCEAE) PROVIDES NOVEL INSIGHTS INTO CELL‐WALL SYNTHESIS PROCESSES IN RELATION TO THE CELL CYCLE1

Cell‐cycle effects in phytoplankton have both general and specific influences over a variety of cellular processes. Understanding these effects requires that the majority of cells in a culture are progressing through the same cell‐cycle stage, which requires synchronous growth. We report the development of a silicon starvation–recovery synchrony for the first diatom with a sequenced genome, Thalassiosira pseudonana Hasle et Heimdale, which provides several novel insights into the process of cell‐wall formation. After 24 h of silicate starvation, flow cytometry measurements indicated that 80% of the cells were arrested in the early G1 phase of the cell cycle and then upon silicate replenishment progressed synchronously through the cycle. An early G1‐arrest point was not previously documented in diatoms. After silicate replenishment, girdle‐band synthesis was confined to a particular period in G1, and cells did not lengthen in accordance with each girdle band added, which has implications related to cell growth and separation processes in diatoms. Measurements of silicic acid uptake, intracellular pools, and silica incorporation into the cell wall, coupled with fluorescence visualization of newly synthesized cell‐wall structures, provide the first direct measurements of silica amounts in individual girdle bands and valves in a diatom. Fluorescence imaging indicated why valves in T. pseudonana do not have to reduce in size with each generation and enabled visualization of intermediates in structure formation. The development of a synchrony procedure for T. pseudonana enables correlation of cellular events with the cell cycle, which should facilitate the use of genomic information.