Regional Differences In Composition Research Articles

Exploring the regional typicality of Australian Shiraz wines using untargeted metabolomics

Background and Aims Shiraz is the most widely planted winegrape cultivar in Australia. Sensory studies have indicated that different grapegrowing regions in Australia produce distinct styles of Shiraz wines that differ in flavour characteristics. The current project aimed to characterise the underlying volatile composition associated with regional Shiraz wine styles. Methods and Results Wines were selected from six geographically distinct regions and the volatile compounds were analysed using gas chromatography time-of-flight mass spectrometry to provide a comprehensive and holistic overview of the wine volatilome. A suite of R language based software enabled feature extraction and importance ranking, following an untargeted metabolomics approach. A classification model based on the random forests algorithm using the 80 most important compounds correctly associated all samples to regions. A range of these compounds, including terpenoids, benzenoids, esters, furan derivatives and aliphatic alcohols, has been associated with grape composition, winemaking influences and the ageing process. Conclusions The results suggest that the regional compositional differences in varietal wines may be influenced by all processes in the entire wine production chain. Significance of the Study The current study highlighted the chemical basis underlying the regional typicality of Australian Shiraz wines, and identified specific volatile compounds that may be associated with a region.

Regional differences in the fatty acid composition, and vitamin and carotenoid concentrations in farm bulk milk in Hokkaido, Japan.

In this study, we investigated the regional differences in the composition of farm bulk milk produced at three different dairy areas in Hokkaido, Japan. A field survey was conducted at Central, Tokachi, and North areas of Hokkaido, three or four times a year. At each farm, an interview questionnaire for farm basal data was conducted, and 500ml of bulk tank milk sample was obtained. Fatty acid composition, and vitamin and carotenoid concentrations in the milk samples were determined. In Central and Tokachi areas, corn silage was used as the main forage. In North area, fresh herbage was the dominant feed in the summer season, and grass hay was the main feed in the winter season. Discriminant analysis revealed that the composition of milk samples differed among the areas and seasons. Milk from Central and Tokachi areas contained a higher ratio of linoleic acid compared with that from North area, but there were only slight differences in the composition of milk between Central and Tokachi areas. The concentrations of carotenoids and α-tocopherol were higher in samples from North area and the ratios of trans-vaccenic acid and conjugated linoleic acid were higher in the summer season than in the indoor season.

Regional differences in the composition of Fusarium Head Blight pathogens and mycotoxins associated with wheat in Mexico

Fusarium Head Blight (FHB) is a destructive disease of small grain cereals and a major food safety concern. Epidemics result in substantial yield losses, reduction in crop quality, and contamination of grains with trichothecenes and other mycotoxins. A number of different fusaria can cause FHB, and there are significant regional differences in the occurrence and prevalence of FHB pathogen species and their associated mycotoxins. Information on FHB pathogen and mycotoxin diversity in Mexico has been extremely limited, but is needed to improve disease and mycotoxin control efforts. To address this, we used a combination of DNA sequence-based methods and in-vitro toxin analyses to characterize FHB isolates collected from symptomatic wheat in Mexico during the 2013 and 2014 growing seasons. Among 116 Fusarium isolates, we identified five species complexes including nine named Fusarium species and 30 isolates representing unnamed or potentially novel species. Significant regional differences (P < 0.001) in pathogen composition were observed, with F. boothii accounting for >90% of isolates from the Mixteca region in southern Mexico, whereas F. avenaceum and related members of the F. tricinctum species complex (FTSC) accounted for nearly 75% of isolates from the Highlands region in Central Mexico. F. graminearum, which is the dominant FHB pathogen in other parts of North America, was not present among the isolates from Mexico. F. boothii isolates had the 15-acetyldeoxynivalenol toxin type, and some of the minor FHB species produced trichothecenes, such as nivalenol, T-2 toxin and diacetoxyscirpenol. None of the FTSC isolates tested was able to produce trichothecenes, but many produced chlamydosporol and enniatin B.

LOS PECES GOBIIDAE DE LOS ARRECIFES DEL CARIBE COLOMBIANO. I. ESPECIES, DISTRIBUCION, FRECUENCIA Y ABUNDANCIA

Forty-six species of fishes of the family Gobiidae are reported from the reef environments (mainly coralline) of the Colombian Caribbean. Of these, 11 were previously unknown from the southern Caribbean and 24 are new records for the northern Colombian coast. Forty species occur in the continental coast and 37 in Isla de Providencia. Based on rotenone collections, information on their distribution, frequency and abundance is presented and analyzed. Among the small reef ichthyofauna, gobies are in average more than one fourth of the species, about one third of the individuals, and less than one tenth of thé biomass. The most common species in the whole Colombian Caribbean are Coryphopterus personatus and Gnatholepis thompsoni (present in 68% of the samples), followed by Quisqui/ius hipoliti (57%), Coryphopterus eidolon (52%) and Elacatinus illecebrosum (51%). Regional differences in composition, frequency and abundance of the reef gobiid fauna are noted. A key for the identification of the 17 studied genera is included.

Diversity of Fusarium head blight populations and trichothecene toxin types reveals regional differences in pathogen composition and temporal dynamics

Analyses of genetic diversity, trichothecene genotype composition, and population structure were conducted using 4086 Fusarium graminearum isolates collected from wheat in eight Canadian provinces over a three year period between 2005 and 2007. The results revealed substantial regional differences in Fusarium head blight pathogen composition and temporal population dynamics. The 3ADON trichothecene type consistently predominated in Maritime provinces (91%) over the sampled years, and increased significantly (P<0.05) between 2005 and 2007 in western Canada, accounting for 66% of the isolates in Manitoba by the end of the sampling period. In contrast, 3ADON frequency was lower (22%, P<0.001) in the eastern Canadian provinces of Ontario and Québec and did not change significantly between 2005 and 2007, resulting in two distinct longitudinal clines in 3ADON frequency across Canada. Overall, genetic structure was correlated with toxin type, as the endemic population (NA1) was dominated by 15ADON isolates (86%), whereas a second population (NA2) consisted largely of 3ADON isolates (88%). However, the percentage of isolates with trichothecene genotypes that were not predictive of their genetic population assignment (recombinant genotypes) increased from 10% in 2005 to 17% in 2007, indicating that trichothecene type became an increasingly unreliable marker of population identity over time. In addition, there were substantial regional differences in the composition of recombinant genotypes. In western and maritime provinces, NA2 isolates with 15ADON genotypes were significantly more common than NA1 isolates with 3ADON genotypes (P<0.001), and the reverse was true in the eastern provinces of Québec and Ontario. Temporal trends in recombinant genotype composition also varied regionally, as the percentage of 15ADON isolates with NA2 genetic backgrounds increased approximately three fold in western and Maritime provinces, while the opposite trends were observed in Québec and Ontario. The results indicate that F. graminearum population dynamics in Canada have been influenced by a complex adaptive landscape comprising different regional selective pressures, and do not reflect a simple model of dispersal and integration following the introduction of a novel pathogen population. In addition, we identified F. graminearum strains that produce the recently discovered A-trichothecene mycotoxin (NX-2) for the first time in Canada, representing a significant expansion of the known range of NX-2 producing strains in North America.

Regional variations in the histology of porcine skin.

Porcine skin is commonly used as a model for human skin injury and as a source material for biologic scaffold materials. Although remarkable similarities between porcine and human skin exist, regional anatomic variations present in human skin are also present in porcine skin. The objective of this study was to evaluate the structure of porcine skin from 11 different anatomic regions in the American Yorkshire crossbreed. Both qualitative and quantitative methods were used, with emphasis on epidermal and dermal thickness, hair follicle density, and collagen and elastin composition and distribution. The results showed that significant regional differences in skin histology exist, particularly with regard to the thickness of the dermis and epidermis and the amount of collagen and elastin within each tissue. Differences were also seen in the distribution of type I and type III collagen within the dermis. Therefore, while porcine skin shares many similarities with human skin, distinct regional differences in composition and morphology exist. This study highlights the importance of appreciating these regional differences to avoid misinterpretation of experimental results when using porcine skin as a human analogue.

Longitudinal variation and effects of habitat on biodiversity of Australasian temperate reef fishes

AbstractAimLatitudinal gradients in marine biodiversity of fishes are well documented but comparatively little is known about longitudinal patterns. The objective of this study was to describe the distributional patterns in biodiversity and assemblage structure of temperate reef‐associated fishes in two habitats (kelp forests and open reefs) in each of four regions at comparable latitudes spanning a large longitudinal range (&gt; 5000 km; 117.91° E–174.81° E).LocationNew Zealand, New South Wales, South Australia and Western Australia.MethodsTotal abundance, species richness, evenness, average taxonomic distinctness and variation in taxonomic distinctness were calculated from underwater visual counts of individual fish species and were analysed using ANOVA. Compositional change in fish communities was analysed using PERMANOVA and non‐metric multi‐dimensional scaling at the species level and at the family level.ResultsPatterns in univariate diversity measures did not show a clear longitudinal gradient and depended on the particular variable being considered. There was, however, a clear longitudinal gradient of turnover in species composition but this disappeared in family‐level analyses. The effects of habitat were also relatively stronger in family‐level analyses.Main conclusionsWe propose that ecological communities in similar habitats may be assembled according to a general ‘village hypothesis’, whereby an assemblage contains certain essential functional components. Regions having similar environmental characteristics are expected to have a full suite of these functional components. Thus, provided families reflect functional forms, this may explain the similarity among communities from vastly different regions when analysed at the family level. In contrast, the radiation of species within families may be regionally specific, depending on the history of oceanographic connectivity, microclimate and finer niche specialization, thus yielding strong regional differences in composition at this finer taxonomic level.

Regional differences in species composition and toxigenic potential among Fusarium head blight isolates from Uruguay indicate a risk of nivalenol contamination in new wheat production areas

Members of the Fusarium graminearum species complex (FGSC) are the primary cause of Fusarium head blight (FHB) of wheat, and frequently contaminate grain with trichothecene mycotoxins that pose a serious threat to food safety and animal health. The species identity and trichothecene toxin potential of 151 FGSC isolates collected from wheat in Uruguay were determined via multilocus genotyping. Although F. graminearum with the 15ADON trichothecene type accounted for 86% of the isolates examined, five different FGSC species and all three trichothecene types were identified in this collection. This is the first report of Fusarium asiaticum, Fusarium brasilicum, Fusarium cortaderiae, and Fusarium austroamericanum from Uruguay. In addition, we observed significant (P<0.001) regional differences in the composition of FGSC species and trichothecene types within Uruguay. Isolates of F. graminearum with the 15ADON type were the most prevalent in western provinces (95%), while F. asiaticum (43%) and the NIV type (61%) predominated in the new wheat production zone in Cerro Largo along Uruguay's eastern border with Brazil. F. graminearum isolates (15ADON type) were significantly (P<0.005) more aggressive on wheat than were isolates from the other species examined (NIV or 3ADON types). However, F. graminearum isolates (15ADON type) were significantly (P<0.05) more sensitive to tebuconazole than isolates from other species (NIV type). These results document substantial heterogeneity among the pathogens responsible for FHB in Uruguay. In addition, the regional predominance of the NIV trichothecene type is of significant concern to food safety and indicates that additional monitoring of nivalenol levels in grain may be required.

Analysis of natural diatom communities reveals novel insights into the diversity of long chain polyamine (LCPA) structures involved in silica precipitation

The intricately nanopatterned siliceous frustules of diatoms are formed under the control of template organic molecules, some of which are tightly incorporated into the frustule during formation. Long chain polyamines (LCPAs) attract dissolved silicic acid species, enhance silica precipitation and play a role in frustule nanopattern formation. LCPAs thus play a central biogeochemical role, linking the cycling of organic matter with the cycling of silicic acid in the photic zone of the upper ocean. Their distribution and molecular diversity in the environment are as yet unknown. We used high performance liquid chromatography electrospray ionization–mass spectrometry (HPLC–ESI–MSn) to investigate the distribution and molecular diversity of aliphatic LCPAs extracted from the frustules of diatoms in mixed marine plankton communities collected within the euphotic zone of the northeastern Pacific coast, Bering Sea, and Puget Sound estuary. An astonishing variety of over 100 natural LCPAS with complex distribution patterns was found in each sample. Structural variation included degree of methylation, overall chain length, presence of secondary amine functionalities, incorporation of quaternary ammonium and occurrence of sulfonated derivatives. Putrescine-based LCPAs with various degrees of methylation and N-methyl propylamine repeat units were ubiquitous. Although some LCPA species overlapped between samples, there were regional differences in composition and structural characteristics. The structural variety of LCPAs employed by diatoms to produce their nanopatterned silicified exoskeleton could inform biomimetic studies of silica precipitation.

The scientific rationale for the C1XS X-ray spectrometer on India's Chandrayaan-1 mission to the moon

The UK-built Chandrayaan-1 X-ray Spectrometer (C1XS) will fly as an ESA instrument on India's Chandrayaan-1 mission to the Moon, launched in October 2008. C1XS builds on experience gained with the earlier D-CIXS instrument on SMART-1, but will be a scientifically much more capable instrument. Here we describe the scientific objectives of this instrument, which include mapping the abundances of the major rock-forming elements (principally Mg, Al, Si, Ti, Ca and Fe) in the lunar crust. These data will aid in determining whether regional compositional differences (e.g., the Mg/Fe ratio) are consistent with models of lunar crustal evolution. C1XS data will also permit geochemical studies of smaller scale features, such as the ejecta blankets and central peaks of large impact craters, and individual lava flows and pyroclastic deposits. These objectives all bear on important, and currently unresolved, questions in lunar science, including the structure and evolution of any primordial magma ocean, as revealed by vertical and lateral geochemical variations in the crust, and the composition of the lunar mantle, which will further constrain theories of the Moon's origin, thermal history and internal structure.

Lead isotope constraints on the genesis of Pb–Zn deposits in the Neoproterozoic Vazante Group, Minas Gerais, Brazil

The Neoproterozoic Vazante Group at the western border of the São Francisco Craton, Brazil, hosts the largest Zn–Pb district in South America. Several authors have classified this mineral district as Mississippi Valley-type (MVT), based on the intimate association with carbonates and the epigenetic character of most ore bodies. In this paper, we present 47 new lead isotope data from four deposits located along the 300 km N–S Vazante–Paracatu–Unai linear trend. Pb isotope ratios indicate sources with relatively high U/Pb and Th/Pb ratios. Considering the 206Pb/ 204Pb and 208Pb/ 204Pb ratios as indicative parameters for the source, we suggest an upper crustal source for the metals. The small variation on the Pb isotope ratios compared to those observed in the classical MVT deposits, and other geological, fluid inclusion and sulphur isotopic data indicates a metallogenic event of long duration. It was characterized by focused circulation of hydrothermal fluids carrying metals from the basement rocks and from the sedimentary pile. The data obtained are more compatible with an evolution model similar to that of IRISH-type deposits. The existence of three Pb isotopic populations could be the result of regional differences in composition of the source rocks and in the fluid–rock interaction since the mineralization is a long-term process.

Absorption of Volatile Organic Compounds in Biodiesel: Determination of Infinite Dilution Activity Coefficients by Headspace Gas Chromatography

It has been reported in previous work, that biodiesel (rapeseed oil methyl ester) is a highboiling solvent well-suited for VOC (volatile organic compound) absorption. In order to use biodiesel effectively as an absorption solvent for a specific waste gas problem, it is important to determine the activity coefficients, at infinite dilution, of the VOCs to be separated with biodiesel. Here, a detailed investigation of VLE (vapor–liquid-equilibrium) of three volatile organic compounds of industrial significance, benzene, toluene and 1,2-dichloroethane (1,2-DCE) has been carried out in order to determine their infinite dilution activity coefficients in biodiesel. Biodiesel is a methanol transesterificated product of rape seed oil, and as a natural product exhibits regional differences in composition. There is, therefore, a need to characterize the material. Accordingly molar mass of biodiesel was determined and commercial available biodiesel types, winter biodiesel with volatile additives and summer biodiesel without volatile additives, were discussed from the point of view of a scrubbing process. Gas chromatography (GC) and Head Space GC techniques were employed. The molar mass of biodiesel has been determined as 294.86 kg kmol−1. The infinite dilution activity coefficients compare well with the data from previous work and the UNIFAC predictions representative for methyl oleate, which is the major component in biodiesel.

Regional differences in composition of the perforatorium and outer periacrosomal layer of the rat spermatozoon as revealed by immunocytochemistry

The rat perforatorium is the part of the perinuclear theca that underlies the acrosomic system. It appears to be composed of several polypeptides. The main objective of this study was to determine the distribution of seven of these perforatorial polypeptides in the head of the rat spermatozoon. For this purpose, polyclonal antibodies were affinity purified from these polypeptides and tested 1) for their distribution on electron-microscope sections of late spermatids and spermatozoa by immunogold labeling and 2) for their specificity on Western blots of denatured perforatorial polypeptides by immunoblotting. Immunoblotting showed that all seven of the prominent perforatorial polypeptides had epitopes in common. Immunogold labeling of spermatozoa showed that antibodies against the 13, 13.4, and 16 kDa polypeptides were restricted in their localization to the thicker apical portion of the perforatorium and to the inner zone of the ventral spur. However, antibodies against the 34, 43, 57, and 63 kDa polypeptides reacted with the entire perforatorium but, in addition, reacted with the inner part of the ventral spur and with a portion of the "outer periacrosomal layer" lying between the plasma membrane and the outer acrosomal membrane. These results suggest 1) that there are regional differences in protein composition of the perforatorium, of the outer periacrosomal layer, and of the postacrosomal dense lamina; and 2) that perforatorial polypeptides may not necessarily be restricted to the subacrosomal region, but may also compose portions of the outer periacrosomal layer and postacrosomal dense lamina. Based on both immunoblotting and immunocytochemical results, using an antiactin monoclonal antibody that recognizes all known isoforms of actin, actin was not detected in the perforatorium of step 19 spermatids or spermatozoa. Actin, however, together with the seven perforatorial polypeptides tested, was present in the subacrosomal space of elongating spermatids before the process of condensation of the perforatorium takes place.

Illite/Smectite Diagenesis in Devonian Lacustrine Mudrocks from Northern Scotland and Its Relationship to Organic Maturity Indicators

Devonian rocks from the Orcadian Basin show an extreme range of organic maturity. Mean vitrinite reflectance ranges from 0-6 to 10.5~ and spore colour from yellow- orange to black. Illite/smectite (I/S) is abundant in the clay fraction of lacustrine mudrocks and shows variation in expandability from 30 to < 5~. A correlation is observed between expandability and vitrinite reflectance, but the specific relationship is different in the Moray Firth and the Caithness-Orkney areas. Illite 'crystallinity' measurements in the Caithness- Orkney area are also correlated with vitrinite reflectance. Geological evidence favours an I/S origin from precursor smectite, and mineral and chemical analyses of lacustrine shales show no evidence for regional differences in composition that might affect iUitization rates. The different relationships within each region are believed to result from the different relative response of organic maturity indicators and clay minerals to temperature and reaction time. The lower I/S expandabilities in the Caithness-Orkney region at a given vitrinite reflectance are attributed to relatively longer burial times.

Biochemical and immunological analyses of cytoskeletal domains of neurons.

We have used cultured sympathetic neurons to identify microtubule proteins (tubulin and microtubule-associated proteins [MAPs]) and neurofilament (NF) proteins in pure preparations of axons and also to examine the distribution of these proteins between axons and cell bodies + dendrites. Pieces of sympathetic ganglia containing thousands of neurons were plated onto culture dishes and allowed to extend neurites. Dendrites remained confined to the ganglionic explant or cell body mass (CBM), while axons extended away from the CBM for several millimeters. Axons were separated from cell bodies and dendrites by dissecting the CBM away from cultures, and the resulting axonal and CBM preparations were analyzed using biochemical, immunoblotting, and immunoprecipitation methods. Cultures were used after 17 d in vitro, when 40-60% of total protein was in the axons. The 68,000-mol-wt NF subunit is present in both axons and CBM in roughly equal amounts. The 145,000- and 200,000-mol-wt NF subunits each consist of several variants which differ in phosphorylation state; poorly and nonphosphorylated species are present only in the CBM, whereas more heavily phosphorylated forms are present in axons and, to a lesser extent, the CBM. One 145,000-mol-wt NF variant was axon specific. Tubulin is roughly equally distributed between CBM and axon-like neurites of explant cultures. MAP-1a, MAP-1b, MAP-3, and the 60,000-mol-wt MAP are also present in the CBM and axon-like neurites and show distribution patterns similar to that of tubulin. In contrast, MAP-2 was detected only in the CBM, while tau and the 210,000-mol-wt MAP were greatly enriched in axons compared to the CBM. In immunostaining analyses, MAP-2 localized to cell bodies and dendrite-like neurites, but not to axon-like neurites, whereas antibodies to tubulin and MAP-1b localized to all regions of the neurons. The regional differences in composition of the neuronal cytoskeleton presumably generate corresponding differences in its structure, which may, in turn, contribute to the morphological differences between axons and dendrites.

Mature Mesophytic Hardwood Forest: Community Transitions, by Layer, from East‐Central Minnesota to Southeastern Michigan

Fragments of old—growth forest in which sugar maple (Acer saacharum) is a principal dominant, i.e., late—successional mesophytic forests, were sampled layer by layer across a floristic gradient from east—central Minnesota to southeastern Michigan, USA. This includes the northern Maple—Basswood region ("Big Woods" section) and northwestern Beech—Maple region as described by E. L. Braun (1950). All sampled areas were relatively undisturbed, at least 0.5 ha (surrounded on all sides by &gt;30 m of forest), and occupied similar sites: deep, gently sloping, well—drained drift with high water—holding capacity. The object was (1) to determine whether the community importance of species that are common throughout the study area differs significantly from region to region, perhaps as a result of within—layer competition with species that are restricted floristically, but become important as soon as their ranges are entered (e.g., beech, Fagus grandifolia), and (2) to determine whether regional differences in tree composition correlate with regional differences in the composition of inferior layers. Regional differences in composition of mature trees tended to support Braun's earlier findings that "climax" forests on mesic sites west of the beech border are characterized by the prevalence of basswood (Tilia americana) as a codominant, but as soon as the beech border is crossed, beech is the principal codominant. Basswood ranked at least second in density in 70% of the Big Woods stands (mean density = 53.4 boles/ha), but in only 20% of the stands within the range of beech (mean density = 8.3 boles/ha), where beech ranked at least second in 73% of the stands (mean density = 42.0 boles/ha). Mean basal area of basswood was 14.0 m2/ha west of the beech border and 1.6 to the east, compared with 8.7 for beech. Basswood, in fact, attained about the same relative density (0.20) and basal area (0.36) averaged over all stands in the Big Woods as beech did within its range (i.e., 0.23 and 0.29, respectively). (Mean total density per stand in the two regions was 267 ± 38 and 184 ± 37 boles/ha; mean total basal area was 39.0 ± 5.4 and 30.8 ± 4.6 m2ha.) Regional differences in composition were not readily apparent when inferior layers (vascular plants &lt;2 m tall) were sampled quantitatively, excluding rare species and species with restricted floristic distributions. When understories so defined were clustered according to several measures of species importance, broad overlap of stand groups resulted in each case. Overlap was often similar to that obtained when understories were clustered on the basis of species weightings randomly allocated to stands, that is, when the distribution of scores for each species is not changed, but scores are assigned to stands randomly.

Anorogenic metaluminous and peraluminous granite plutonism in the mid-proterozoic of Wisconsin, USA

A magmatic gap from 1.82 to 1.76 b.y. in the Lake Superior region represents the transition from synorogenic calc-alkaline igneous activity of the Penokean Orogeny to anorogenic potassic granophyric granite and ignimbrite. This paper deals with the petrogenetic evolution of 1.76 b.y. granites which represent a major change in source material and conceivably tectonic setting. Although perhaps related to a termination of the Penokean Orogeny by melting of a tectonically thickened crust during collision, these post-Penokean granites may represent the initial appearance of anorogenic, potentially rift-related igneous activity that was widespread throughout North America during late Precambrian time. These post-Penokean granites are too iron-rich and Al-poor to be considered calc-alkaline, a compositional feature shared with most anorogenic igneous activity of continental regions. Within this suite in central and northern Wisconsin, regional differences in composition indicate at least two different granite magma types: one a metaluminous suite of biotite and biotite-hornblende granite and a peraluminous suite of two-mica granite. The systematic compositional differences (Al, Fe/Mg, Ba/Sr, REE) in the two magma suites are likely the result of small differences in residue mineralogy and/or source composition. In general, the degree of fusion was small (10%) and probably of relatively young Penokean material. Both suites have a range of composition due to feldspar dominated fractional crystallization. Removal of the accessory minerals apatite, zircon, and allanite resulted in the REE depletion with differentiation of the two-mica granites. The granites intruded into the upper levels of the crust, and the appearance of primary celadonitic muscovite and subsolvus alkali feldspars (silicic members only) in the two mica granites indicate crystallization at depths of 10–11 km. The biotite granites contain both hypersolvus and subsolvus members and are intruded at depths less than 6 km with the more shallow members generating major volumes of ignimbrite. As a marked departure from the characteristics of most anorogenic granites, these melts crystallized at fairly oxidizing conditions (higher for the two-mica suite) as reflected in the composition of biotite, predominance of magnetite over ilmenite, and early appearance of the Fe-Ti oxides in the crystallization sequence.

Some regional compositional differences within Tertiary—Recent orogenic magmas

Regional differences in the compositions of Recent orogenic magmas, mainly from the circum-Pacific areas, are investigated with the aid of a data file of over 7000 analyses, which contains major-oxide data and, where available, trace elements and modal mineralogy. Each analysis is also coded as belonging to one of the following magma series: calc-alkali, low-K, high-K or shoshonitic, as defined by Peccerillo and Taylor. The lavas can be divided chemically into two broad groups. One group, which includes the western U.S.A. (but not the Cascades), S. America and the Mediterranean, can be regarded as “continental”, while the other, which includes the S.W. and N.W. Pacific, and the Aleutians, Alaska and Cascades, can be regarded as “island-arc”. The inclusion of the Cascades in the latter is, however, somewhat anomalous and indicates that the geochemistry of the lavas is not controlled entirely by their tectonic setting. Central America seems to be intermediate to these two groups. Cluster analysis and multiple discriminant analysis have been used to investigate the chemical and mineralogical differences between these groups. The mineralogical characteristics are consistent with the idea that increasingly K-rich magma series in the orogenic regions may tend to be increasingly hydrous. It is concluded that the K-enrichment in the “continental” group is due to crustal interaction.

Hemlock Stands from Wisconsin to Nova Scotia: Transitions in Understory Composition Along a Floristic Gradient

The understories of 71 small stands strongly dominated by hemlock (Tsuga canadensis [L.] Carr.) were sampled in a transect from northern Wisconsin to Nova Scotia. Stands selected for sampling were at least 100 yr old and had homogeneous overstories composed of at least 75% hemlock. Stand area varied from 0.04 to 2.4 ha, with most stands between 0.2 and 0.8 ha. All stands were local areas of strong hemlock dominance within a much larger mixed forest. The hemlock understories, as a group, are not a distinctive community type with respect to composition (vascular plants). There are no species relatively abundant in the hemlock stands that are not also abundant in other types of mesophytic forest. Presence and coverage of species vary greatly from stand to stand, even on similar soils and topography, suggesting that community organization is haphazard. However, a few species are almost ubiquitous (Tsuga canadensis, Acer rubrum, Maianthemum canadense, Dryopteris austriaca), and others consistently attain high coverage when present (e.g., Taxus canadensis, Oxalis montana). Also, the mean association (Cole's index) between pairs of common species (50—69% presence) significantly exceeds the mean association in stands not strongly dominated by a single overstory species (i.e., mixed hardwood forests with varying proportions of sugar maple and basswood in the overstory). Half of the 66 understory species that are at least moderately common in non—hemlock forest throughout the study area are rare or absent under hemlock in some parts of the transect, yet common in other parts. Regional differences in composition, however, are not discrete. Regional differences in understory composition are poorly correlated with regional differences in the potential hemlock forest flora (i.e., plants observed growing in hemlock forests). Community transitions also correspond poorly to certain climatic differences between regions, such as the length of the freeze—free period.

The cortex of Xenopus laevis embryos: regional differences in composition and biological activity.

The cortex of fertilized Xenopus laevis eggs undergoes regional changes in its composition and morphogenetic activity during the first three divisions. Gray crescent and animal pole cortex of stage 1 (1-cell) and stage 4 (8-cell) embryos each contain a characteristic array of proteins. Implantation of pieces of cortex into the blastocoel of midblastula embryos was used to assay their inductive capacity. The gray crescent cortex was shown to be the only region that had significant axis-inducing activity. This activity increased from stage 1 to stage 4.