Application of vibrational spectroscopy in the quality assessment of Buchu oil obtained from two commercially important Agathosma species (Rutaceae)

Quality assessment of natural raw materials and derived consumer products is often done using conventional analytical techniques such as liquid and gas chromatography which are expensive and time consuming. This paper reports on the use of vibrational spectroscopy techniques as possible alternatives for the rapid and inexpensive assessment of the quality of ‘buchu oil’ obtained from two South African species; Agathosma betulina and Agathosma crenulata belonging to the Rutaceae family. Samples of A. betulina (55) and A. crenulata (16) were collected from different natural localities and cultivation sites in South Africa. The essential oil was obtained by hydrodistillation and scanned on Near infrared (NIR), mid infrared (MIR) and Raman spectrometers. The spectral data obtained was processed using chemometric techniques and orthogonal partial least squares discriminant analysis (OPLS-DA) was used to clearly differentiate between A. betulina and A. crenulata. The OPLS-DA technique also proved to be a useful tool to identify wave regions that contain biomarkers (peaks) that contributed to the separation of the two species. The three spectroscopy techniques were also evaluated for their ability to accurately predict the percentage composition of seven major compounds that occur in A. betulina ‘buchu’ oil. Using GC–MS reference data, calibration models were developed for the MIR, NIR and Raman spectral data to predict/profile the major compounds in ‘buchu oil’. A comparison of the three spectroscopy techniques showed that MIR together with PLS algorithms produced the best model (R²X = 0.96; R²Y = 0.88 and Q²Ycum = 0.85) for the quantification of six of the seven major oil constituents. The MIR model showed high predictive power for pseudo-diosphenol (R² = 0.97), isomenthone (R² = 0.97), menthone (R² = 0.90), limonene (R² = 0.91), pulegone (R² = 0.96) and diosphenol (R² = 0.85). These results illustrate the potential of MIR spectroscopy as a rapid and inexpensive alternative to predict the major compounds in buchu oil.     

Mid-infrared spectroscopy and short wave infrared hyperspectral imaging—A novel approach in the qualitative assessment of Harpagophytum procumbens and H. zeyheri (Devil's Claw)

Harpagophytum procumbens (Burch.) DC. ex Meisn. subsp. procumbens (Pedaliaceae) is an important African medicinal plant growing in the Kalahari region of southern Africa. This species, together with its close taxonomic ally Harpagophytum zeyheri are collectively referred to as Devil's Claw and are used interchangeably for the treatment of inflammation-related disorders. Although the two taxa are botanically and chemically similar, H. zeyheri contains lower levels of harpagoside and these two species have not been proven to exhibit equipotent pharmacological activity. Due to these taxonomic similarities, effective quality control methods are required to distinguish between the two species. Differentiation between the two species was achieved using single point mid-infrared spectroscopy in combination with chemometric data analysis. The orthogonal projections to latent structures discriminant analysis (OPLS-DA) model had good predictive ability, as illustrated by the model statistics: R²X (cum predictive + orthogonal) = 0.86 and Q² (cum) = 0.63. Short wave infrared (SWIR) hyperspectral imaging could distinguish between the two species with acceptable model statistics: R²X and R²Y of 0.99 and 0.78, respectively. This study demonstrated that both MIR single point spectroscopy and SWIR hyperspectral imaging coupled with chemometric modelling are reliable and rapid methods to determine the authenticity of Harpagophytum spp.     

Environmental determinants of Gulf Menhaden (Brevoortia patronus) oil content in the northern Gulf of Mexico

Gulf Menhaden (Brevoortia patronus) are a species of commercial and ecological importance in the northern Gulf of Mexico, provisioning the second largest fishery by weight, in the United States, and providing critical ecosystem services in the coastal region. The recruitment and productivity dynamics of the stock are influenced by a suite of environmental factors but an understanding of the factors that determine individual variation in oil content (an indicator of an individual’s commercial value to the fishery and its dietary value to predators) has not been well described. In this work I describe the temporal dynamics of oil content and determine the demographic characteristics that provide predictive power to describe annual contrasts. I relate the predicted patterns in oil yield to a suite of seasonal environmental data series including: the magnitude of spring Mississippi River discharge, spring wind vectors, and the preceding winter El Nino conditions. Two uncorrelated (r = 0.06, p = 0.81) population-level predictor variables were identified that have explanatory power to describe temporal patterns in oil content (L kg⁻¹); a weight-at-length power function parameter (a) and the von Bertalanffy asymptotic fork length (L_∞, mm FL): L kg⁻¹ = − 0.158 − 0.026*a − 0.00163*L_∞ (p < 0.05, R² = 0.42). Analysis of the impacts of environmental variables on the oil content of Gulf Menhaden was evaluated comprehensively in a Bayesian framework by transforming the observed oil content information from two sources to a common scale. Parameters relating oil content to spring Mississippi River discharge and the preceding winter (December–February) El Nino Southern Oscillation index resulted in sample distributions from the posterior where zero was outside the 95% credible interval. This work contributes to the understanding of Gulf Menhaden as a prey species in the Gulf of Mexico and indicates that the value of the species to both the fishery and predators exhibits relatively large inter-annual variability controlled, in part, by seasonal environmental conditions.     

Molecular analysis of the bacterial community in digestive tract of rabbit

This work aimed to study the stability over time of the bacterial community in cæcum and fæces of the rabbit (diversity index and structure) without experimental disturbance and to evaluate its relationships with environmental parameters. Soft and hard fæces of 14 rabbits were sampled for 5 weeks while cæcal content was sampled on the 3rd week (by surgery) and the 5th week (at slaughter). Bacterial communities were assessed by studying CE-SSCP profiles of 16S rRNA genes fragments. Redox potential, pH, NH3-N concentration and volatile fatty acid concentrations were measured in the cæcum. Data showed that bacterial communities of soft and hard fæces barely differed from that of the cæcum (ANOSIM-R < 0.25; p < 0.05). Without disturbance, the bacterial communities of fæces were stable over time (ANOSIM-R < 0.25; p < 0.001). However, the bacterial communities of cæcum and fæces were affected by the surgery (ANOSIM-R = 0.22–0.33; p < 0.001). The cæcal content was an acidic (pH = 6.03 ± 0.33) and an anaerobic environment (redox potential = ?160 ± 43 mV). Only the redox potential was correlated with the diversity index of the bacterial community of the cæcum (R² = 0.35; p < 0.05) and no environmental parameters were correlated to its structure.     

Edraianthus × lakusicii (Campanulaceae) a new intersectional natural hybrid: morphological and molecular evidence

The genus Edraianthus A.DC. has a center of distribution in the Balkans and it is one of the most prominent groups of endemic plants in this region. During our recent fieldtrip to Mt. Lov?en (Montenegro), putative hybrid individuals were encountered, morphologically intermediate between two sympatric taxa, E. tenuifolius (E. sect. Edraianthus) and E. wettsteinii subsp. lovcenicus (E. sect. Uniflori). Multivariate morphometric and molecular analyses were carried out to investigate the occurrence of hybridization between these two species. As a result, a new nothospecies is described here, Edraianthus × lakusicii V. Stevanovi? & D. Laku?i?, a natural hybrid between E. tenuifolius and E. wettsteinii subsp. lovcenicus. At present, this hybrid is known only from the single locality of Mt. Lov?en. Its population size is estimated to be <50 mature individuals and the estimated “area of occupancy” is smaller than 1 km².     

Biodegradation of Tapis blended crude oil in marine sediment by a consortium of symbiotic bacteria

Biodegradation rate and the high molecular weight hydrocarbons are among the important concerns for bioremediation of crude oil. Inoculation of a non-oil-degrading bacterium as supplementary bacteria increased oil biodegradation from 57.1% to 63.0% after 10 days of incubation. Both the oil-degrading bacteria and the non-oil-degrading bacteria were isolated from Malaysian marine environment. Based on the 16S rDNA sequences, the oil-degrading bacteria was identified as Pseudomonas pseudoalcaligenes (99% similarity) while the non-oil-degrading bacterium was Erythrobacter citreus (99% similarity). E. citreus does not grow on crude oil enriched medium under present experimental condition but it withstands 5000 mg kg^?1 Tapis blended crude oil in sediment. Under optimal condition, the oil-degrading bacterium; P. pseudoalcaligenes, alone utilized 583.3 ± 3.8 mg kg^?1 (57.1%) at the rate of 3.97 × 10^?10 mg kg^?1 cell^?1 day^?1 Tapis blended crude oil from 1000 mg kg^?1 oil-contaminated sediment. Inoculation of E. citreus as the supplementary bacteria to P. pseudoalcaligenes enhanced biodegradation. The bacterial consortium degraded 675.8 ± 18.5 mg kg^?1 (63.0%) Tapis blended crude oil from the 1000 mg kg^?1 oil-contaminated sediment. Biodegradation rate of the bacterial consortium increased significantly to 4.59 × 10^?10 mg kg^?1 cell^?1 day^?1 (p = 0.02). Improvement of the oil degradation by the bacterial consortium was due to the synergetic reaction among the bacterial inoculants. There are two implications: (1) E. citreus may have a role in removing self-growth-inhibiting compounds of P. pseudoalcaligens. (2) P. pseudoalcaligenes degraded Tapis blended crude oil while E. citreus competes for the partially degraded hydrocarbons by P. pseudoalcaligenes. P. pseudoalcaligenes forced to breakdown more hydrocarbons to sustain its metabolic requirement. The bacterial consortium degraded 78.7% of (C₁₂–C₃₄) total aliphatic hydrocarbons (TAHs) and 74.1% of the 16 USEPA prioritized polycyclic aromatic hydrocarbons.     

An untargeted metabolomic approach in the chemotaxonomic assessment of two Salvia species as a potential source of α-bisabolol

α-Bisabolol is a commercially important aroma chemical currently obtained from the Candeia tree (Vanillosmopsis erythropappa). Continuous unsustainable harvesting of the Candeia tree has prompted the urgent need to identify alternative crops as a source of this commercially important sesquiterpene alcohol. A chemotaxonomic assessment of two Salvia species indigenous to South Africa is presented and recommended as a potential source of α-bisabolol. The essential oil obtained by hydrodistillation of the aerial parts was analysed by gas chromatography coupled to mass spectrometry (GC–MS) and mid-infrared spectroscopy (MIRS). Orthogonal projections to latent structures–discriminant analysis (OPLS–DA) were used for multivariate classification of the oils based on GC–MS and MIRS data. Partial least squares (PLS) calibration models were developed on the MIRS data for the quantification of α-bisabolol using GC–MS as the reference method. A clear distinction between Salvia stenophylla and Salvia runcinata oils was observed using OPLS–DA on both GC–MS and MIRS data. The MIR calibration model showed high coefficient of determination (R² = 0.999) and low error of prediction (RMSEP = 0.540%) for α-bisabolol content.     

Immunodiagnosis of anti-Toxocara vitulorum IgG antibodies by using commercially available bovine ELISA Kit in bovine of Potohar region Pakistan

The Toxocarosis is a common zoonotic parasitic infection caused by three etiological agents T. cati, T. canis and T. vitulorum. It has a severe impact on health and economy especially in countries where it is endemic. The study was conducted from June 2013–2014. The blood samples were collected from (n = 270) cattle grazing in the Potohar region. The sera were separated and subjected to anti-Toxocara ELISA and results revealed an overall seroprevalence of 16.67% (45/270) in cattle. The relationship between age groups and seroprevalence of T. vitulorum indicated a statistically significant difference (p = .01, χ² = 16.81) and non-significant was sex group of cattle and seroprevalence of T. vitulorum (p = .859, χ² = 0.032). The results also revealed a statistically non-significant difference between cattle breed and Toxocara infection (p = .142, χ² = 5.424). From the study, we concluded that indirect ELISA is a highly efficient assay for timely diagnosis of infection in order to adapt control strategies to mitigate the infection. The present study recommended the need to develop ELISA by using excretory-secretory (ES) T. vitulorum antigen in order to reduce the cost of commercial kits for mass screening purposes. Furthermore, the result of the current study also suggested and conducting similar nature of studies in other agroecological zones of Pakistan, which will help to provide baseline epidemiological data of parasitic diseases.     

Kocuria tytonicola,new bacteria from the preen glands of American barn owls (Tyto furcata)

Although birds are hosts to a large number of microorganisms, microbes have rarely been found in avian oil glands. Here, we report on two strains of a new bacterial species from the preen oil of American barn owls (Tyto furcata). Phenotypic as well as genotypic methods placed the isolates to the genus Kocuria. Strains are non-fastidious, non-lipophilic Gram-positive cocci and can be unambiguously discriminated from their closest relative Kocuria rhizophila DSM 11926^T. In phylogenetic trees, the owl bacteria formed a distinct cluster which was clearly separated from all other known Kocuria species. The same conclusion was drawn from MALDI-TOF MS analyses. Once again, the new bacterial strains were very similar to one another, but exhibited substantial differences when compared to the most closely related species. Besides, the results of the biochemical tests, optimum growth conditions and pigmentation differed from closely related Kocuria spp. Finally, ANIb values of less than 87% provided striking evidence that the isolates recovered from American barn owls represent a hitherto undescribed species, for which we propose the name Kocuria tytonicola sp. nov. The type strain is 489^T (DSM 104133^T = LMG 29945^T, taxonumber TA00340).     

Evaluation of insecticidal activity of the essential oil of Allium chinense G. Don and its major constituents against Liposcelis bostrychophila Badonnel

Water-distilled essential oil from the dried bulbs of Allium chinense (Liliaceae) was analyzed by gas chromatography–mass spectrometry (GC–MS). Eighteen compounds, accounting for 98.4% of the total oil, were identified and the main components of the essential oil of A. chinense were methyl allyl trisulfide (30.7%), dimethyl trisulfide (24.1%), methyl propyl disulfide (12.8%) and dimethyl disulfide (9.6%) followed by methyl allyl disulfide (3.4%) and methyl propyl trisulfide (3.6%). The essential oil exhibited contact toxicity against the booklice (Liposcelis bostrychophila) with an LC₅₀ value of 441.8 μg/cm² while the two major constituents, dimethyl trisulfide and methyl propyl disulfide had LC₅₀ values of 153.0 μg/cm² and 738.0 μg/cm² against the booklice, respectively. The essential oil of A. chinense possessed strong fumigant toxicity against the booklice with an LC₅₀ value of 186.5 μg/l while methyl allyl trisulfide (LC₅₀ = 90.4 μg/l) and dimethyl trisulfide (LC₅₀ = 114.2 μg/l) exhibited stronger fumigant toxicity than methyl propyl disulfide (LC₅₀ = 243.4 μg/l) and dimethyl disulfide (LC₅₀ = 340.8 μg/l) against the booklice. The results indicated that the essential oil and its major constituents have potential for development into natural insecticides or fumigants for control of insects in stored grains.     

Predicting feed intake using modelling based on feeding behaviour in finishing beef steers

Current techniques for measuring feed intake in housed cattle are both expensive and time-consuming making them unsuitable for use on commercial farms. Estimates of individual animal intake are required for assessing production efficiency. The aim of this study was to predict individual animal intake using parameters that can be easily obtained on commercial farms including feeding behaviour, liveweight and age. In total, 80 steers were used, and each steer was allocated to one of two diets (40 per diet) which consisted of (g/kg; DM) forage to concentrate ratios of either 494:506 (MIXED) or 80:920 (CONC). Individual daily fresh weight intakes (FWI; kg/day) were recorded for each animal using 32 electronic feeders over a 56-day period, and individual DM intakes (DMI; kg/day) subsequently calculated. Individual feeding behaviour variables were calculated for each day of the measurement period from the electronic feeders and included: total number of visits to the feeder, total time spent at the feeder (TOTFEEDTIME), total time where feed was consumed (TIMEWITHFEED) and average length of time during each visit to the feeder. These feeding behaviour variables were chosen due to ease of obtaining from accelerometers. Four modelling techniques to predict individual animal intake were examined, based on (i) individual animal TOTFEEDTIME relative expressed as a proportion of the dietary group (GRP) and total GRP intake, (ii) multiple linear regression (REG) (iii) random forests (RF) and (iv) support vector regressor (SVR). Each model was used to predict CONC and MIXED diets separately, giving eight prediction models, (i) GRP_CONC, (ii) GRP_MIXED, (iii) REG_CONC, (iv) REG_MIXED, (v) RF_CONC, (vi) RF_MIXED, (vii) SVR_CONC and (viii) SVR_MIXED. Each model was tested on FWI and DMI. Model performance was assessed using repeated measures correlations (R²_RM) to capture the repeated nature of daily intakes compared with standard R², RMSE and mean absolute error (MAE). REG, RF and SVR models predicted FWI with R²_RM = 0.1–0.36, RMSE = 1.51–2.96 kg and MAE = 1.19–2.49 kg, and DMI with R²_RM = 0.13–0.19, RMSE = 1.15–1.61 kg and MAE = 0.9–1.28 kg. The GRP models predicted FWI with R²_RM = 0.42–0.49, RMSE = 2.76–3.88 kg and MAE = 2.46–3.47 kg, and DMI with R²_RM = 0.32–0.44, RMSE = 0.32–0.44 kg, MAE = 1.55–2.22 kg. Whilst more simplistic GRP models showed higher R²_RM than regression and machine learning techniques, these models had larger errors, likely due to individual feeding patterns not being captured. Although regression and machine learning techniques produced lower errors associated with individual intakes, overall precision of prediction was too low for practical use.     

Variation in essential oil composition of Leonotis leonurus,an important medicinal plant in South Africa

Leonotis leonurus widely used by traditional healers in southern Africa for treatment of various ailments, is well known for its reported psychoactive properties. The present study was undertaken to investigate the variation in essential oil composition between geographically distinct populations of L. leonurus in South Africa using gas chromatography. Plant material (n = 50) was collected from three provinces of South Africa. Essential oils of the aerial parts were obtained by hydrodistillation and analysed using one and two dimensional gas chromatography. Twenty-six compounds accounted for more than 80% of the total composition of the oil. Eight major constituents in the oil, representing about 50% of the total oil composition, were identified by both GC–MS–FID and GCxGC–ToF–MS. These major compounds were trans-β-ocimene (0.1–5.0%), cis-β-ocimene (0.1–31.5%), β-caryophyllene (0.3–15.0%), caryophyllene oxide (0.1–5.0%), α-humulene (0.4–18.2%), γ-elemene (0.4–10.6%), α-cubebene (0.2–12.0%) and germacrene D (0.1–22.1%). Marked similarities exist in the essential oil composition between populations; differences are mostly quantitative when determined by GC–MS–FID, while GCxGC–ToF–MS data reveals both quantitative and qualitative differences.Untargeted multivariate analysis was performed using SIMCA-P + 14.0 PCA and OPLS-DA methods, identifying two distinct clusters, inland and coastal populations.     

Global gene methylation profiling of common warts caused by human papillomaviruses infection

Infection with the human papillomaviruses (HPV) often involves the epigenetic modification of the host genome. Despite its prevalence among the population, host genome methylation in HPV-induced warts is not clearly understood. In this study, genome-wide methylation profiling was carried out on paired healthy skin and wart samples in order to investigate the effects that benign HPV infection has on gene methylation status. To overcome this gap in knowledge, paired wart (n = 12) and normal skin (n = 12) samples were obtained from Arab males in order to perform DNA extraction and subsequent genome-wide methylation profiling on the Infinium Methylation EPIC Bead Chip microarray. Analysis of differential methylation revealed a clear pattern of discrimination between the wart and normal skin samples. In warts, the most differentially methylated (DM) genes included long non-coding RNAs (AC005884, AL049646.2, AC126121.2, AP001790.1, and AC107959.3), microRNAs (MIR374B, MIR596, MIR1255B1, MIR26B, and MIR196A2),snoRNAs (SNORD114-22, SNORD70, and SNORD114-31), pseudogenes (AC069366.1, RNU4ATAC11P, AC120057.1, NANOGP3, AC106038.2, TPT1P2, SDC4P, PKMP3, and VN2R3P), and protein-coding genes (AREG, GJB2, C12orf71, AC020909.2, S100A8, ZBED2, FABP7, and CYSLTR1). In addition, pathway analysis revealed that, among the most differentially methylated genes, STAT5A, RARA, MEF2D, MAP3K8, and THRA were the common regulators. It can be observed that HPV-induced warts involve a clear and unique epigenetic alteration to the host genome.     

Effect of Clove (Syzygium aromaticum) spice as microbial inhibitor of resistant bacteria and Organoleptic Quality of meat

For centuries, spices have been utilized as flavourants, colourants and as preservatives in food. Moreover, spices possess various antimicrobial properties with massive health benefits for the treatment and management of ailments and diseases. The present study was focused on three (3) aspects; (1) isolation and molecular identification of bacteria from the meat; (2) to determine the antimicrobial activity of the spices against the pathogens; (3) to assess the organoleptic properties of the spiced meat. A total of twelve (n = 12) spices evaluated against forty (n = 40) spoilage food-borne pathogenic bacteria (Escherichia coli and Enterococci spp.). The spice extracts were tested using disk diffusion method to determine the inhibition abilities. The results show that clove and black seed cumin extract exhibited excellent antibacterial activity against most pathogenic bacteria. Clove displayed the highest inhibition zone of 18 mm against E. coli (EcFwS1). Clove extract was the most inhibitor followed by black cumin, whereas extracts of thyme and cinnamon showed weak antibacterial activities against the tested strains. The most sensitive strain to spice extracts was Enterococcus spp. (EnFmL1) and the most resistant strain being E. coli. (EcFmS1 and EcFpL1). Untreated meat showed that E. coli and Enterococcus spp. count was 4.4 * 10⁵ ± 3.4 * 10⁵ and 2.2 * 10⁵ ± 3.6 * 10⁴ cfu/mL respectively after 7 days while the single dose of clove showed 5.4 * 10⁴ ± 4.4 * 10² cfu/mL of E. coli and 1.7 * 10⁵ ± 4.1 * 10⁴ cfu/mL of Enterococcus spp. The organoleptic characteristics such as colour, texture, odour, pH, shape of the single dose of clove on the meat was overall acceptable.     

Assessment of the genetic variation of chamomile (Matricaria chamomilla L.) populations using phytochemical,morphological and ISSR markers

Inter simple sequence repeat (ISSR) markers were used to assess the genetic diversity of 23 populations of chamomile. Ten primers were applied, producing 193 polymorphic bands. The polymorphic bands were analysed using Simple Matching (SM) similarity index and UPGMA cluster analysis. The resulting dendrogram consisted of four major groups which were in accordance to the geographical regions from which the populations had originated. Populations from North-western (NW), South-Eastern (SE), Central (C) Iran and Europe tended to be classified separately into groups. The highest gene diversity was observed in populations from the Central regions of Iran (0.25). Principal coordinate analysis (PCoA) confirmed the results of cluster analysis, while morphological classification was not related to molecular results. The population from Hungary had the greatest yield of essential oil (0.88 gr/dw), whereas for Iranian ones the greatest and the lowest essential oil yields belonged to NW (Aza = 0.6 and Ard = 0.7) and C (Isf 4, Isf 5 and Isf 6 = 0.44) regions, respectively. The results of the present study could contribute to a better understanding and management of conservation and exploitation of the chamomile germplasm.     

Emulsifying properties of a marine bacterial exopolysaccharide

Exopolysaccharide produced by a marine Enterobacter cloaceae (designated as EPS 71a) emulsified hexane, benzene, xylene, kerosene, paraffin oil, cottonseed oil, coconut oil, jojoba oil, castor oil, groundnut oil and sunflower oil. However, it could form stable emulsions with groundnut oil and hexane at optimal concentration of 1 mg ml⁻¹. Further increase in concentration of EPS 71a did not show noteworthy increase in emulsification indices. Emulsions with groundnut oil and hexane were stable up to 10 days between pH 2 and 10 and in the presence of sodium chloride in the range of 5–50 mg ml⁻¹ at 35–37 °C. EPS 71a formed stable emulsion with xylene as compared to commercial gums such as arabic, tragacanth, karaya and xanthan.     

The role and contribution of the seagrass Posidonia oceanica (L.) Delile organic matter for secondary consumers as revealed by carbon and nitrogen stable isotope analysis

The δ¹³C and δ¹⁵N values of primary producers and consumers were studied to obtain information on the trophic role of Posidonia oceanica L. Delile, the dominant primary producer, in a Mediterranean shallow environment (the Stagnone di Marsala, western Sicily). δ¹³C strongly discriminated between pelagic and benthic pathways, with the former based on phytoplankton and the latter on a mixed pool of seagrass detritus, epiphytes and benthic algae as carbon sources. A particularly important trophic role appears to be performed by the vegetal epiphytic community on seagrass leaves (δ¹³C = –14.9 ± 0.1‰), which supports most of the faunal seagrass community (i.e. Amphipoda, Isopoda, Tanaidacea; δ¹³C = –14.9 ± 0.1‰, –12.5 ± 0.1‰ and –14.8 ± 1.0‰, respectively). Although P. oceanica (δ¹³C = –11.3 ± 0.3‰) does not seem to be utilised by consumers via grazing (apart from a few Palaemonidae species with δ¹³C value of –10.8 ± 1.8‰), its trophic role may be via detritus. P. oceanica detritus may be exploited as a carbon source by small detritivore invertebrates, and above all seems to be exploited as a nitrogen reservoir by both bottom and water column consumers determining benthic–pelagic coupling. At least three trophic levels were detected in both the pelagic (mixture of phytoplankton and cyanobacteria, zooplankton, juvenile transient fish) and benthic (sedimentary organic matter and epiphytes, small seagrass-associated invertebrates, larger invertebrates and adult resident fish) pathways.     

Effects of phosphorus and nitrogen amendments on the growth of Egeria najas

The effect of nutrient addition on the growth of E. najas was evaluated in a dose response experiment using sand amended with phosphorus (P) and nitrogen (N), and in enrichment trials with N and P amendments to natural sediments. Plants, water and sediment came from lagoons of the Upper Paraná River Floodplain and from Itaipu Reservoir (Brazil). Relative growth rates (RGRs) of E. najas shoots, based on dry mass (DM), varied from 0.03 to 0.060 d⁻¹ for both nutrients. Root:shoot biomass ratios were related to sediment exchangeable P (r = −0.419; P = 0.03) and N (r = −0.54; P = 0.006), however root RGR was not related to sediment nutrient concentrations. When natural sediments were amended with N and P, neither shoot nor root RGRs differed among treatments for substrata from either the reservoir or the floodplain lagoons (P > 0.05). Comparison of nutrient concentrations measured in natural sediments collected from several sites in both the Upper Paraná River Floodplain (range 49–213 μg P g⁻¹ DM; 36–373 μg N g⁻¹ DM) and Itaipu Reservoir (range 43–402 μg P g⁻¹ DM; 7.9–238 μg N g⁻¹ DM) showed that sediment N and P from these systems usually exceeded minimum requirements necessary for E. najas growth, as measured in the dose response experiment. Together, these results indicate that E. najas, at least in early stages of development, responds to sediment nutrient amendments and relies upon bottom sediments to meet its N and P requirements and that for at least two Brazilian ecosystems, growth of this species is not limited by insufficient sediment N or P. Thus, reducing N and P in water is not enough to control E. najas growth in short time periods in these ecosystems.     

Rahnella victoriana sp. nov., Rahnella bruchi sp. nov., Rahnella woolbedingensis sp. nov., classification of Rahnella genomospecies 2 and 3 as Rahnella variigena sp. nov. and Rahnella inusitata sp. nov., respectively and emended description of the genus Rahnella

Isolations from oak symptomatic of Acute Oak Decline, alder and walnut log tissue, and buprestid beetles in 2009–2012 yielded 32 Gram-negative bacterial strains showing highest gyrB sequence similarity to Rahnella aquatilis and Ewingella americana. Multilocus sequence analysis (using partial gyrB, rpoB, infB and atpD gene sequences) delineated the strains into six MLSA groups. Two MLSA groups contained reference strains of Rahnella genomospecies 2 and 3, three groups clustered within the Rahnella clade with no known type or reference strains and the last group contained the type strain of E. americana. DNA–DNA relatedness assays using both the microplate and fluorometric methods, confirmed that each of the five Rahnella MLSA groups formed separate taxa. Rahnella genomospecies 2 and 3 were previously not formally described due to a lack of distinguishing phenotypic characteristics. In the present study, all five Rahnella MLSA groups were phenotypically differentiated from each other and from R. aquatilis. Therefore we propose to classify the strains from symptomatic oak, alder and walnut and buprestid beetles as: Rahnella victoriana sp. nov. (type strain FRB 225^T = LMG 27717^T = DSM 27397^T), Rahnella variigena sp. nov. (previously Rahnella genomosp. 2, type strain CIP 105588^T = LMG 27711^T), Rahnella inusitata sp. nov. (previously Rahnella genomosp. 3, type strain DSM 30078^T = LMG 2640^T), Rahnella bruchi sp. nov. (type strain FRB 226^T = LMG 27718^T = DSM 27398^T) and Rahnella woolbedingensis sp. nov. (type strain FRB 227^T = LMG 27719^T = DSM 27399^T).