Guayule as a feedstock for lignocellulosic biorefineries using ammonia fiber expansion (AFEX) pretreatment

Natural rubber latex extraction from guayule leaves behind greater than 90% (by weight) of agricultural residue as a feedstock suitable for conversion to biofuels via a thermochemical or biochemical route. Untreated guayule shrub and bagasse (after latex extraction) has shown to be very recalcitrant to enzymatic hydrolysis, necessitating application of a chemical pretreatment to enhance cellulase accessibility. The objective of this work was to carry out detailed compositional analysis, ammonia fiber expansion (AFEX¹) pretreatment, enzymatic hydrolysis and ethanol fermentation for various guayule-derived biomass fractions. Plant feedstocks tested were derived from two sources; (a) a mature 2007 AZ-2 whole guayule shrub plant obtained from USDA/ARS² research fields, and (b) the guayule latex-extracted commercial grade bagasse (62505) from Yulex Corporation. Compositional analysis and enzymatic hydrolysis were carried out using standard NREL³ protocols (www.nrel.gov/biomass/analytical_procedures.html). AFEX pretreatment was carried out using concentrated ammonium hydroxide at elevated temperatures for desired residence times in a pressurized reactor. Yeast fermentations on biomass hydrolyzates were carried out micro-aerobically using Saccharomyces cerevisiae (424A strain) in shake flasks.AFEX pretreatment was found to substantially improve overall enzymatic digestibility by 4-20 fold for both untreated guayule shrub and latex-extracted bagasse. Maximum glucan and xylan conversion achieved for the latex-extracted bagasse was 40% and 50%, respectively. The yeast was readily able to ferment both glucose and xylose to ethanol from the guayule bagasse hydrolyzate with or without external nutrient supplementation (i.e., yeast extract and tryptone). Our results highlight the possible utilization of guayule as a feedstock for lignocellulosic refineries co-producing natural rubber latex and biofuels. However, further process improvements (e.g., lignin/resin extraction and cellulose decrystallization using a modified AFEX process) are necessary to increase the effectiveness of ammonia-based pretreatments for further enhancing enzymatic digestibility of guayule-derived hardwood biomass.     

The influence of landscape characteristics and home-range size on the quantification of landscape-genetics relationships

A common approach used to estimate landscape resistance involves comparing correlations of ecological and genetic distances calculated among individuals of a species. However, the location of sampled individuals may contain some degree of spatial uncertainty due to the natural variation of animals moving through their home range or measurement error in plant or animal locations. In this study, we evaluate the ways that spatial uncertainty, landscape characteristics, and genetic stochasticity interact to influence the strength and variability of conclusions about landscape-genetics relationships. We used a neutral landscape model to generate 45 landscapes composed of habitat and non-habitat, varying in percent habitat, aggregation, and structural connectivity (patch cohesion). We created true and alternate locations for 500 individuals, calculated ecological distances (least-cost paths), and simulated genetic distances among individuals. We compared correlations between ecological distances for true and alternate locations. We then simulated genotypes at 15 neutral loci and investigated whether the same influences could be detected in simple Mantel tests and while controlling for the effects of isolation-by-distance using the partial Mantel test. Spatial uncertainty interacted with the percentage of habitat in the landscape, but led to only small reductions in correlations. Furthermore, the strongest correlations occurred with low percent habitat, high aggregation, and low to intermediate levels of cohesion. Overall genetic stochasticity was relatively low and was influenced by landscape characteristics.     

Epidemiologic investigation of Mycobacterium bovis in a population of cats

OBJECTIVE: To determine whether cats exposed at a residence were infected with Mycobacterium bovis, whether the tuberculin skin test can identify cats infected with M bovis, and whether an ELISA could identify tuberculosis-infected cats. ANIMALS: 20 domestic cats exposed to a cat with laboratory-confirmed disseminated M bovis infection. PROCEDURE: Cats were administered a tuberculin skin test and monitored for 72 hours. Blood and fecal samples were collected. Cats were then euthanatized, and postmortem examinations were performed. Tissues were examined grossly and histologically for signs of mycobacteriosis. Pooled tissue samples and fecal samples were submitted for mycobacterial culture. Blood samples were examined for evidence of tuberculosis by use of a comparative ELISA. RESULTS: 4 cats had positive responses for the ELISA, and 2 cats had suspicious responses. All tuberculin skin tests yielded negative results. No gross or histologic lesions of tuberculosis were detected in any tissues, and mycobacteria were not isolated from tissues or feces obtained from the 20 cats. CONCLUSIONS AND CLINICAL RELEVANCE: All cats that had positive or suspicious responses for the ELISA were offspring of the cat with tuberculosis. Evidence of tuberculosis was not seen in other cats at the residence, the owner, or the attending veterinarian. The most likely source of tuberculosis for the infected cat was through the consumption of M bovis-infected wildlife carcasses or offal. Because M bovis is endemic in wildlife in northeastern Michigan, there is a risk of exposure to tuberculosis in companion animals, their owners, and attending veterinarians.     

Epitheliotropic T-cell lymphoma in 2 half-sibling bontebok

We diagnosed epitheliotropic T-cell lymphoma of the forestomachs in 2 aged, half-sibling, zoo-managed bontebok (Damaliscus pygargus pygargus). One bontebok also had mesenteric lymph node and cutaneous involvement. Both animals had a history of chronic abdominal distension and diminished body condition that resulted in euthanasia. At autopsy, both animals had marked ruminal distension with diffusely blunted ruminal papillae and reticular crests. In case 1, there was an increased amount and particle length of the ruminoreticular fibrous material with scant fluid, and a 2-cm diameter focus of cutaneous crusting adjacent to a mammary teat. In case 2, the rumen and reticulum were fluid-distended with decreased fibrous material. Histologically in case 1, the rumen, reticulum, omasum, and skin had intraepithelial nests and sheets of neoplastic small lymphocytes; in case 2, the rumen and reticulum had a similar neoplastic cell population. Immunohistochemically, neoplastic lymphocytes were immunoreactive for CD3 and negative for CD20, confirming the diagnosis of epitheliotropic T-cell lymphoma.     

An Exploratory Investigation of Polar Organic Compounds in Waters from a Lead�CZinc Mine and Mill Complex

Surface water samples were collected in 2006 from a lead mine?Cmill complex in Missouri to investigate possible organic compounds coming from the milling process. Water samples contained relatively high concentrations of dissolved organic carbon (DOC; greater than 20 mg/l) for surface waters but were colorless, implying a lack of naturally occurring aquatic humic or fulvic acids. Samples were extracted by three different types of solid-phase extraction and analyzed by electrospray ionization/mass spectrometry. Because large amounts of xanthate complexation reagents are used in the milling process, techniques were developed to extract and analyze for sodium isopropyl xanthate and sodium ethyl xanthate. Although these xanthate reagents were not found, trace amounts of the degradates, isopropyl xanthyl thiosulfonate and isopropyl xanthyl sulfonate, were found in most locations sampled, including the tailings pond downstream. Dioctyl sulfosuccinate, a surfactant and process filtering aid, was found at concentrations estimated at 350 ??g/l at one mill outlet, but not downstream. Release of these organic compounds downstream from lead?Czinc mine and milling areas has not previously been reported. A majority of the DOC remains unidentified.     

In vitro comparison of proximal ulnar osteotomy and distal ulnar osteotomy with release of the interosseous ligament in a canine model

Objective: To determine the effect of proximal ulnar osteotomy (PUO), distal ulnar osteotomy (DUO), and DUO with release of the interosseous ligament (DOLR) on displacement of the proximal ulna at the radioulnar joint. Study Design: Experimental mechanical study. Sample Population: Cadaveric, skeletally mature canine thoracic limb pairs (n=11). Methods: Thoracic limbs disarticulated at the elbow were randomly assigned to 1 of 2 groups: (A) limbs were tested with no treatment (NOTX), then with PUO; (B) limbs were tested with DUO followed by DOLR. A distraction force was applied to the proximal ulna with the distal limb secured in a frame, and displacement of the proximal ulnar segment at the radioulnar joint was recorded. Results: Mean displacement was 0.36 mm (95% confidence interval [CI]: 0?1.12 mm) in the NOTX group, 4.68 mm (95% CI: 3.82–5.55 mm) for PUO limbs, 0.95 mm (95% CI: 0.52–1.39 mm) for the DUO group, and 4.36 mm (95% CI: 3.71–5.02 mm) for the DOLR group. Mean ulnar displacement of the DOLR group was significantly different compared with the DUO group, but there was no significant difference between the PUO and DOLR groups. Conclusions: No significant difference was observed in displacement of the proximal ulnar segment after DOLR compared with PUO.     

Stem injection of a systemic insecticide to control Uraba lugens on urban Lophostemon confertus trees

BACKGROUND: Uraba lugens Walker (Lepidoptera: Nolidae) has the potential to become a serious pest of susceptible forestry and urban trees in New Zealand. Stem injection of insecticides provides a method for the control of U. lugens in public locations where foliar applications are not suitable. Field and laboratory studies were conducted in 2009 and 2010 to determine a dose response profile of U. lugens larvae to acephate injected at 0.0, 0.25, 0.50 and 1.00 g cm^?1 tree diameter measured at breast height (dbh). The concentration of the injected solution varied across years. RESULTS: The highest mortality (85–100%) of U. lugens larvae occurred at 1.00 g acephate injected cm^?1 dbh. The lower rates (0.25 and 0.50 g acephate cm^?1) were more effective in 2010 than in 2009, a factor attributed to the change in volume of injected solution. CONCLUSION: Systemic injections of acephate at rates above 0.50 g cm^?1 dbh provide a tool for the management of U. lugens in public places. It is recommended that stem injection operations for control of U. lugens larvae be timed to coincide with the emergence of first instars so that larvae are exposed to lethal insecticide doses. Copyright © 2011 Society of Chemical Industry     

Growth and stem quality responses to fertilizer application by 21 loblolly pine clones in the Virginia Piedmont

Clonal forestry offers the opportunity to increase yields, enhance uniformity and improve wood characteristics. Intensive silvicultural practices, including fertilization, will be required to capture the full growth potential of clonal plantations. However, variation in nutrient use efficiency that exists among clones could affect growth responses. Our research objective was to determine the range of growth response and stem form quality due to fertilization in clones of Pinus taeda. A split-plot experimental design was used, with the whole plots being two levels of fertilizer application (fertilizer versus control) and the split plot factor being 25 clones. Whole plot treatments were blocked and replicated four times. Six years after planting and five years after fertilizer application, a repeated measures analysis showed fertilizer-by-time and clone-by-time interactions affected volume (p < 0.10). Clone-by-fertilizer interactions were observed for tree height, branch traits, and a metric of foliar display. These interactions were primarily due to scale-effect phenomena rather than rank shifts. The magnitude of fertilizer responses observed in a small number of genotypes suggests that knowledge of fertilizer responses in widely deployed genotypes, if developed prior to mid-rotation, may better optimize management of single-clone blocks. Our results further indicate that a range of possibilities exist for the design and application of clone-specific precision silvicultural systems.     

Using a multifaceted approach to reveal avian community responses to natural and anthropogenic effects in a fragmented Southern Mistbelt Forest system,South Africa

Landscape Ecology - Forest loss and fragmentation are major drivers of biodiversity decline globally. However, with the widely recognised notion that biodiversity is multifaceted, few studies have...