Assessment of Four Solvents for Extraction and Analysis of the Chemical Composition of Sansevieria Extrafoliar Nectar Drops by Gas Chromatography-mass Spectrometry

In the latter part of the 20th century, much effort was devoted to elucidating the chemical constituents of floral and extrafloral nectar secretions, with the primary aim of understanding their ecological roles, especially in regards to attracting pollinators. But, nearly all these studies focused on determining sugar and amino acid constituents. Only a few studies have reported more comprehensive assessments of the organic chemical constituents of plants, with none of those reporting such efforts for Sansevieria taxa (common houseplants known to purify air by bioaccumulating pollutants). To address this knowledge gap, we evaluated the efficacy of four organic solvents with distinct polarities (dichloromethane (DCM), ethyl acetate, toluene and hexane) to extract the most diverse suite of organic compounds from extrafoliar nectar drops (n = 12) secreted by motherin-law’s-tongue plant (Sansevieria spp.). Each solvent exhibited unique extraction efficiencies, with DCM extracting the greatest number of unique compounds (141), followed by hexane (113), ethyl acetate (58) and toluene (43). Compound class distributions varied with solvent type, with aliphatic hydrocarbons dominating in all but the ethyl acetate extracts. We detected 105 unique aliphatic compounds in the DCM extracts, followed by 69, 28 and 9 in the hexane, toluene and ethyl acetate extracts, respectively. Alcohols predominated in the ethyl acetate extracts. We are aware of no published studies reporting such analytical determinations of the organic compound inventories of Sansevieria extrafoliar nectars. Validation of this methodology provides the impetus to study various other plant secretions of known and unknown utility

Draft Genome Sequence of Vibrio coralliilyticus strain OCN008 Isolated from Kāneʻohe Bay, Hawaiʻi.

Vibrio coralliilyticus is a Gram-negative bacterium found in seawater and is associated with diseased marine organisms. Strains of V. coralliilyticus have been shown to infect coral from multiple genera. We report the draft genome sequence of V. coralliilyticus strain OCN008, the third V. coralliilyticus genome to be sequenced

ABC Transporter Required for Intercellular Transfer of Developmental Signals in a Heterocystous Cyanobacterium

In the filamentous cyanobacterium Anabaena, patS and hetN encode peptide-derived signals with many of the properties of morphogens. These signals regulate the formation of a periodic pattern of heterocysts by lateral inhibition of differentiation. Here we show that intercellular transfer of the patS- and hetN-dependent developmental signals from heterocysts to vegetative cells requires HetC, a predicted ATP-binding cassette transporter (ABC transporter). Relative to the wild type, in a hetC mutant differentiation resulted in a reduced number of heterocysts that were incapable of nitrogen fixation, but deletion of patS or hetN restored heterocyst number and function in a hetC background. These epistasis results suggest that HetC is necessary for conferring self-immunity to the inhibitors on differentiating cells. Nine hours after induction of differentiation, HetC was required for neither induction of transcription of patS nor intercellular transfer of the patS-encoded signal to neighboring cells. Conversely, in strains lacking HetC, the patS- and hetN-encoded signals were not transferred from heterocyst cells to adjacent vegetative cells. The results support a model in which the patS-dependent signal is initially transferred between vegetative cells in a HetC-independent fashion, but some time before morphological differentiation of heterocysts is complete, transfer of both signals transitions to a HetC-dependent process

Dynamic cratering of graphite : experimental results and simulations

The cratering process in brittle materials under hypervelocity impact (HVI) is of major relevance for debris shielding in spacecraft or high-power laser applications. Amongst other materials, carbon is of particular interest since it is widely used as elementary component in composite materials. In this paper we study a porous polycrystalline graphite under HVI and laser impact, both leading to strong debris ejection and cratering. First, we report new experimental data for normal impacts at 4100 and 4200 m s-1 of a 500-μm-diameter steel sphere on a thick sample of graphite. In a second step, dynamic loadings have been performed with a high-power nanosecond laser facility. High-resolution X-ray tomographies and observations with a scanning electron microscope have been performed in order to visualize the crater shape and the subsurface cracks. These two post-mortem diagnostics also provide evidence that, in the case of HVI tests, the fragmented steel sphere was buried into the graphite target below the crater surface. The current study aims to propose an interpretation of the results, including projectile trapping. In spite of their efficiency to capture overall trends in crater size and shape, semi-empirical scaling laws do not usually predict these phenomena. Hence, to offer better insight into the processes leading to this observation, the need for a computational damage model is argued. After discussing energy partitioning in order to identify the dominant physical mechanisms occurring in our experiments, we propose a simple damage model for porous and brittle materials. Compaction and fracture phenomena are included in the model. A failure criterion relying on Weibull theory is used to relate material tensile strength to deformation rate and damage. These constitutive relations have been implemented in an Eulerian hydrocode in order to compute numerical simulations and confront them with experiments. In this paper, we propose a simple fitting procedure of the unknown Weibull parameters based on HVI results. Good agreement is found with experimental observations of crater shapes and dimensions, as well as debris velocity. The projectile inclusion below the crater is also reproduced by the model and a mechanism is proposed for the trapping process. At least two sets of Weibull parameters can be used to match the results. Finally, we show that laser experiment simulations may discriminate in favor of one set of parameters

Exploring Molecular Simulations of a Plausible Prebiotic Reduced Phospholipid Using Hyperchem Software

How the first cells emerged from the primordial milieu is one of the great questions in science. Biomolecular emergence scenarios abound in the literature, but the lack of bioaccessible phosphate and molecular oxygen on the primordial Earth has posed formidable challenges for deducing emergence pathways. One idea gaining wide acceptance invokes delivery of the phosphide mineral schreibersite ((Fe,Ni)3P) to Earth via meteorite impacts ca. 4.2 billion years ago, whereupon they were corroded to reduced phosphorous oxyacids and phosphonates in primordial aquatic environments. We previously proposed that these reduced phosphorus forms could readily combine with putative geochemical species in shallow mineral-rich alkaline hydrothermal systems to form reduced phospholipid analogs of contemporary phosphate-based phospholipids (Fitch, N.W., K.L. Even, L.J. Leinen and M.O. Gaylor. 2016. Plausible prebiotic assembly of a primitive reduced phospholipid from meteoritic phosphorus on the primordial earth. Proceedings of the South Dakota Academy of. Science 95:176.). Lacking resources to empirically validate this idea, we explored “water box” simulations of the proposed phospholipid structure using the HyperChem software package. Simulation results showed the hydrophobic tails migrating away from water molecules, while hydrophilic heads migrated towards them, resulting in quasistacking behaviors consistent with those of known amphiphiles in water. Inspired by these results, we are now investigating more complex primordial simulation scenarios

The hetZ Gene Regulates Heterocyst Formation in Anabaena sp. strain PCC 7120

To form a complex multicellular organism, stem cells must differentiate into each cell/tissue type along proper spatiotemporal scales. The study of differentiation and organismal development has historically been conducted in prokaryotes due to their genetic and morphological simplicity. Anabaena sp. strain PCC 7120 is a multicellular filamentous cyanobacterium that differentiates a morphologically distinct secondary cell type, the heterocyst, in response to a lack of combined environmental nitrogen. Heterocysts are regularly spaced along filaments and fix atmospheric dinitrogen to maintain organismal viability in its absence. Previous work suggested that the hetZ gene is involved in heterocyst differentiation, but the insertional mutants created produced inconsistent phenotypes, so a specific role was not assigned. In this work, a clean hetZ mutant incapable of heterocyst differentiation was generated and the mutation was complemented with the reintroduction of hetZ alone. Overexpression of hetZ bypassed a mutation of hetR, the master regulator of heterocyst differentiation that controls biological pattern formation, but not a mutation of hetP, a regulator of commitment to a differentiated cell fate, which places hetZ roughly between these processes. A protein-protein interaction study showed that HetZ interacts with both HetR and itself. Assessment of transcriptional fusions between the hetZ, hetR, hetP, and patS (an inhibitor of HetR) promoter regions and GFP, and overexpression of HetR in a hetZ mutant resulted in the differentiation of heterocyst-like cells, together indicated that HetZ may act in concert with HetR as an early regulator of development. Taken together, these data describe a non-linear pathway of regulation leading to heterocyst development governed by both HetR and HetZ

Assessment of disease lesion removal as a method to control chronic Montipora white syndrome

Coral colonies in Ka–ne‘ohe Bay, Hawai‘i (USA), are afflicted with the tissue loss disease chronic Montipora white syndrome (cMWS). Here we show that removal of chronic disease lesions is a potential method to slow the progression of cMWS in M. capitata. Over the 24 wk observation period, treatment colonies lost almost half the amount of tissue that was lost by control colonies. The percentage of tissue loss at each sampling interval (mean ± SEM; treatment: 1.17 ± 0.47%, control: 2.25 ± 0.63%) and the rate of tissue loss per day (treatment: 0.13 ± 0.04%, control: 0.27 ± 0.08%) were both significantly lower on treated colonies than control colonies. While lesion removal stopped tissue loss at the initial infection site, which allowed colony healing, it did not prevent re-infection; in all but one of the treated colonies, new cMWS lesions appeared in other areas of the colony but not around the treatment margins. Additionally, the rate of new infections was similar between treatment and control colonies, indicating that physical injury from lesion removal did not appear to increase cMWS susceptibility. These results indicate that lesion removal reduced morbidity in M. capitata exhibiting cMWS but did not stop the disease

Identification and Characterization of Fungal Isolates from Land-applied Sewage Sludge

Approximately eight million dry tons of sewage sludge is generated in the U.S. each year, with more than half of that now land-applied as the primary method of disposal. Despite the proliferation of this practice, little is known about the microbial constituents of these noxious materials. To address this knowledge gap, we isolated and characterized fungi present in archived samples of land-disposed sewage sludge collected from the Snoqualmie National Forest (Washington State). Sludge samples were resuspended in sterile water and 15 fungal isolates were selected and purified on sabouraud dextrose agar plates supplemented with 50 mg/L of chloramphenicol. Fungal morphology was assessed and photodocumented following growth on sabouraud dextrose agar, potato dextrose agar, yeast maltose agar, and malt extract agar. Additionally, pH and temperature tolerance was assessed by growth in liquid cultures of sabouraud dextrose broth from 0 ºC to 50 ºC and determined from pH 2 to 11 at 28 ºC. Carbon source utilization was assessed using Biolog Filamentous Fungi plates. Amplification and sequencing of the ITS region, commonly used in fungal phylogenetic analysis, is in progress to identify each isolate. Phenotypic assessments of growth, carbon utilization, and lactophenol cotton blue staining revealed that sludge-associated fungi are quite varied in size and appearance, but commonly grow in a mesophilic range (10-40 ºC and pH 4-10). Interspecies variation is further evident in the percentage of 31 carbon sources utilized (63-100%). To our knowledge, this work represents the first reported assessment of the fungal community in sewage sludge wastes disposed in the Snoqualmie National Forest

Complete Genome Sequence of Vibrio coralliilyticus Strain OCN014, Isolated from a Diseased Coral at Palmyra Atoll

Vibrio coralliilyticus is a marine gammaproteobacterium that has been implicated as an etiological agent of disease for multiple coral genera on reefs worldwide. We report the complete genome of V. coralliilyticus strain OCN014, isolated from a diseased Acropora cytherea colony off the western reef terrace of Palmyra Atoll

Profiling Volatile Constituents of Homemade Preserved Foods Prepared in Early 1950s South Dakota (USA) Using Solid-Phase Microextraction (SPME) with Gas Chromatography–Mass Spectrometry (GC-MS) Determination

https://scholar.dsu.edu/research-symposium/1013/thumbnail.jp