Differences In Branching Pattern Research Articles

Influence of phenology on waveform features in deciduous and coniferous trees in airborne LiDAR

Information on forest structure is vital for sustainable forest management. Currently, airborne LiDAR remote sensing has been well established as an effective tool to characterize the structure of canopies and forest inventory variables. Radiometry and geometry are highly intertwined in LiDAR remote sensing of forest vegetation and phenology influences the geometric-optical properties of deciduous and evergreen trees causing seasonal variation in LiDAR observations. This variation may be considered as a nuisance or exploited in for example tree species identification. Airborne LiDAR data are also influenced by sensor functioning, acquisition settings, scan geometry and the atmosphere. Reliable estimation of subtle phenological effects calls for data in which the impact of the external factors is minimal. We experimented with such data and explored LIDAR waveforms (WFs) in boreal trees in winter, early summer and late summer. Our objectives were to i) assess the match of the multitemporal LiDAR data for observing true changes in vegetation; ii) quantify the influence of phenology in deciduous and evergreen trees; iii) study the effect of varying scan zenith angle (SZA) and canopy age on WF features in different phenostates; iv) assess the temporal feature correlation in individual living and dead standing trees. A WF-recording pulsed LiDAR sensor unit operating at the wavelength of 1550 nm was used in repeated acquisitions. WF attributes such as energy, peak amplitude and echo width were derived for each pulse and were localized vertically to crown, understory and ground components. Silver and downy birch, black alder, European aspen, Siberian larch, Scots pine, Norway spruce and dead standing spruce formed our strata. Results showed that phenology caused more variation in WF features of deciduous trees compared to evergreen conifers. Deciduous trees displayed substantial between-species variation that was linked with differences in branching pattern, leaf orientation and bark reflectance. Pine displayed a possible winter-early summer anomaly in canopy backscattering that may be linked with changes in foliage clumping or with the role of stamens in early summer trees. Trees displayed positive temporal correlation in WF features and correlations were the strongest in evergreen and deciduous conifers and decreased with time. SZA had minor influence on WF features whereas age exercised a strong effect on many features with parallel variation between species and phenostates. Structural changes following death, i.e. ‘aging’ changed the geometric WF features of dead standing trees. Our results provide new insights for enhancing tree species identification by using WF LiDAR and for LiDAR time-series analysis of vegetation.

FGF18 promotes human lung branching morphogenesis through regulating mesenchymal progenitor cells.

Fibroblast growth factor (FGF) signaling is known to play an important role in lung organogenesis. However, we recently demonstrated that FGF10 fails to induce branching in human fetal lungs as is observed in mouse. Our previous human fetal lung RNA sequencing data exhibited increased FGF18 during the pseudoglandular stage of development, suggestive of its importance in human lung branching morphogenesis. Whereas it has been previously reported that FGF18 is critical during alveologenesis, few studies have described its implication in lung branching, specifically in human. Therefore, we aimed to determine the role of FGF18 in human lung branching morphogenesis. Human fetal lung explants within the pseudoglandular stage of development were treated with recombinant human FGF18 in air-liquid interface culture. Explants were analyzed grossly to assess differences in branching pattern, as well as at the cellular and molecular levels. FGF18 treatment promoted branching in explant cultures and demonstrated increased epithelial proliferation as well as maintenance of the double positive SOX2/SOX9 distal bud progenitor cells, confirming its role in human lung branching morphogenesis. In addition, FGF18 treated explants displayed increased expression of SOX9, FN1, and COL2A1 within the mesenchyme, all factors that are important to chondrocyte differentiation. In humans, cartilaginous airways extend deep into the lung up to the 12th generation of branching whereas in mouse these are restricted to the trachea and main bronchi. Therefore, our data suggest that FGF18 promotes human lung branching morphogenesis through regulating mesenchymal progenitor cells.

Morphometric characterization of microglial phenotypes in human cerebral cortex

BackgroundMicroglia can adopt different morphologies, ranging from a highly ramified to an amoeboid-like phenotype. Although morphological properties of microglia have been described in rodents, little is known about their fine features in humans. The aim of this study was to characterize the morphometric properties of human microglia in gray and white matter of dorsal anterior cingulate cortex (dACC), a region implicated in behavioral adaptation to neuroinflammation. These properties were compared to those of murine microglia in order to gain a better appreciation of the differences displayed by these cells across species.MethodsPostmortem dACC samples were analyzed from 11 individuals having died suddenly without any history of neuroinflammatory, neurodegenerative, nor psychiatric illness. Tissues were sectioned and immunostained for the macrophage marker Ionized calcium binding adaptor molecule 1 (IBA1). Randomly selected IBA1-immunoreactive (IBA1-IR) cells displaying features corresponding to commonly accepted microglial phenotypes (ramified, primed, reactive, amoeboid) were reconstructed in 3D and all aspects of their morphologies quantified using the Neurolucida software. The relative abundance of each morphological phenotype was also assessed. Furthermore, adult mouse brains were similarly immunostained, and IBA1-IR cells in cingulate cortex were compared to those scrutinized in human dACC.ResultsIn human cortical gray and white matter, all microglial phenotypes were observed in significant proportions. Compared to ramified, primed microglia presented an average 2.5 fold increase in cell body size, with almost no differences in branching patterns. When compared to the primed microglia, which projected an average of six primary processes, the reactive and amoeboid phenotypes displayed fewer processes and branching points, or no processes at all. In contrast, the majority of microglial cells in adult mouse cortex were highly ramified. This was also the case following a postmortem interval of 43 hours. Interestingly, the morphology of ramified microglia was strikingly similar between species.ConclusionsThis study provides fundamental information on the morphological features of microglia in the normal adult human cerebral cortex. These morphometric data will be useful for future studies of microglial morphology in various illnesses. Furthermore, this first direct comparison of human and mouse microglia reveals that these brain cells are morphologically similar across species, suggesting highly conserved functions.

The Earliest Case of Extreme Sexual Display with Exaggerated Male Organs by Two Middle Jurassic Mecopterans

BackgroundMany extant male animals exhibit exaggerated body parts for display, defense or offence in sexual selection, such as male birds of paradise showing off colorful and elegant feathers and male moose and reindeers bearing large structured antlers. For insects, male rhinoceros and stag beetles have huge horn-like structure for fighting and competition and some male Leptopanorpa scorpionflies have very long abdominal terminal segments for sexual display and competition. Fossil records of insects having exaggerated body parts for sexual display are fairly rare. One example is two male holcorpids with elongate abdominal segments from sixth (A6) to eighth (A8) and enlarged male genitalia from Eocene, suggesting evolution of these characters occurred fairly late.Principal FindingsWe document two mecopterans with exaggerated male body parts from the late Middle Jurassic Jiulongshan Formation in northeastern China. Both have extremely extended abdominal segments from A6 to A8 and enlarged genitalia, which might have been used for sexual display and, to less extent, for fighting with other males in the competition for mates. Although Fortiholcorpa paradoxa gen. et sp. nov. and Miriholcorpa forcipata gen. et sp. nov. seem to have affinities with Holcorpidae, we deem both as Family Incertae sedis mainly due to significant differences in branching pattern of Media (M) veins and relative length of A8 for F. paradoxa, and indiscernible preservation of 5-branched M veins in hind wing for M. forcipata.Conclusions/SignificanceThese two new taxa have extended the records of exaggerated male body parts of mecopterans for sexual display and/or selection from the Early Eocene to the late Middle Jurassic. The similar character present in some Leptopanorpa of Panorpidae suggests that the sexual display and/or sexual selection due to extremely elongated male abdominal and sexual organs outweigh the negative impact of bulky body and poor mobility in the evolutionary process.

Microdictyon (Chlorophyta, Anadyomenaceae) do Estado da Bahia, Brasil

A morpho-taxonomic study of the genus Microdictyon from the littoral of Bahia, Brazil, is presented. The material studied was obtained by dredging in the infralittoral of the Municipality of Canavieiras, as well as from analysis of material collected along the Bahia coast and deposited in the herbaria SPF and RFA. The genus is characterized by a flat thallus, astipitate, monostromatic, composed of open, reticulate laminae formed by apical cell-coalition. Three species were identified, M. boergesenii, M. pseudohapteron and M. umbilicatum, which were defined based on the type of adhesion pads at the tip of cells, presence or absence of constrictions and differences in branching pattern. Microdictyon pseudohapteron presents crenulated adhesion pads on the tip of cells whereas M. boergesenii and M. umbilicatum present apical annulated adhesion, the latter two differing by branching patterns and the presence or absence of constriction. Descriptions, illustrations and comparison with related taxa are provided.

Relationships between shoot size and branching patterns in 10 broad-leaved tall tree species in a Japanese cool-temperate forest

Within-tree variations in branching patterns (the patterns of daughter shoot production by mother shoots) are the basis of tree architectural plasticity and, therefore, were studied in 10 cool-temperate broad-leaved tall tree species including three species with distinct short shoots. The relationships between mother shoot length versus branching patterns (i.e., the number and size of daughter shoots) were quantified for each species using regression equations. The number and stem length of daughter shoots were greater on longer mother shoots, although the majority of daughter shoots were short on mother shoots of any size. The magnitude of lateral spread of the mother shoot – daughter shoot system relative to that of its main axis extension increased with increasing mother shoot length, indicating weaker apical control on longer mother shoots. Among species, the lower limit of daughter shoot length was shorter and the frequency of short daughter shoots was greater on mother shoots of species with more distinct short shoots. This indicates that species with distinct short shoots effectively avoid branch overcrowding by minimizing daughter shoot extension. Differences in branching patterns among mother shoots of different sizes are discussed in relation to their functional importance for tree architectural development.

Evaluating mechanical wounding as a surrogate for aspen shoot blight caused by Pollaccia americana in the assessment of crop loss

It is difficult to maintain, in trembling aspen (Populus tremuloides), controlled levels of aspen shoot blight (ASB) caused by Pollaccia americana, under field conditions. Thus, simulating the disease by mechanical wounding may be useful in crop-loss assessment. Three treatments were compared to evaluate the suitability of decapitation as a surrogate for ASB: (1) artificial inoculation with P. americana causing ASB and (2) cutting of the shoot between the fifth and sixth expanded leaves (decapitation), both these treatments being later referred to as injury treatments, and (3) no injury (control). The three treatments were applied to trees from four different seed lots, which subsequently grew under field conditions, and to two different clones held in a growth chamber at soil temperatures of 6, 12, or 20 °C. Leader length, frequency of axillary-shoot development, and lateral- and axillary-shoot lengths were evaluated. Trees infected with ASB and trees that were decapitated responded very similarly and had significantly longer leaders and more axillary shoots than did control trees. Although there were significant differences in branching patterns among seed lots, and significant clone and temperature effects on infection, the effects of treatments were typically consistent across all levels of clone, seed lot, and temperature. These results indicate that decapitation could be used to simulate ASB in assessing crop loss.

Genotypic differences in branching pattern and fruiting habit in common walnut (Juglans regia L.).

Architectural analysis of 840 Slovenian walnut (Juglans regia L.) genotypes was performed to determine the most typical and frequent morphological types and to evaluate their vegetative and generative potential. Four branching and fruiting patterns (I-IV) were detected. A 3-year-old fruiting branch, consisting of a 3-year-old shoot plus corresponding 2-year-old and 1-year-old shoots, was used as a structural unit for quantitative analysis. In the intermediate fruit-bearing types with mesotonic and acrotonic branching pattern (types II and III), the total lengths of 3-, 2- and 1-year-old shoots were 385 and 380 cm, respectively, compared with 275 and 253 cm in the terminal and lateral-fruiting types (types I and IV). In type I, 1-year-old shoots had significantly fewer nodes than in other types. In addition, they had a thinner basal diameter than types III and IV, and their angles were the most erect (39 degrees ). Only 0.4 out of 3.6 1-year-old shoots were flowering with one mixed bud with 1.9 female flowers. In type IV, 2-year-old shoots had significantly more nodes and a larger basal diameter than other types. One-year-old shoots in type IV are thicker than those in other types. Ratios between the number of flowering and the total number of 1-year-old shoots were 0.7 in type IV, 0.6 in type III, 0.5 in type II and 0.1 in type I. On 1-year-old shoots in type IV, 1.7 mixed buds with a mean of three female inflorescences per bud were counted. Consequently, the generative potential is highest in type IV and lowest in type I. In types II and III, growth and the ability to bear fruits are more balanced.

Branching Morphology of Gametophytes and Tetrasporophytes of Ceramium Codicola is Related to Phase and Reproductive Structures

AbstractMost red algae with a Polysiphonia‐type life history are regarded as having isomorphic phases. However, some show minor deviations in morphology, including differences in branching reported in female gametophytes and tetrasporophytes of Ceramium. By sampling populations of Ceramium codicola, an epiphyte of Codium fragile, it was possible to characterize the morphology of female and male gametophytes and tetrasporophytes. Branching pattern was characterized by the Strahler method, in which terminal branches are counted as primary branches, and higher order branches are counted where lower order branches meet. Since Ceramium shows dichotomous branching, this method can be used to characterize the degree in which branching is dichotomous. The angle of branching was also measured. Female gametophytes had a higher ratio of primary to secondary branches (3.6–5.1) than male gametophytes (2.5) and tetrasporophytes (2.5–2.6), which have a similar ratio to each other. This indicates that males and tetrasporophytes have a more dichotomous pattern of branching while female gametophytes have more proliferative primary branches. The differences in branching pattern appear to be related to the location of reproductive cells, which occur along the surface of branches in male gametophytes and tetrasporophytes, but occur near the apices in female gametophytes. The branching angle of female and male gametophytes is similar to each other, and greater than that of tetrasporophytes. Therefore, gametophytes and sporophytes differ in branching angle.

Shade-induced changes in the branching pattern of a stoloniferous herb: functional response or allometric effect?

Shade-induced changes in the branching pattern of clonal plants can lead to conspicuous modifications of their growth form and architecture. It has been hypothesized that reduced branching in shade may be an adaptive trait, enabling clonal plants to escape from unfavourable patches in a heterogeneous environment by allocating resources preferentially to the growth of the main axis (i.e. linear expansion), rather than to local proliferation by branching. However, such an adaptionist interpretation may be unjustified if (1) branching frequency is a function of the ontogenetic stage of plants, and if (2) shading slows down the ontogenetic development of plants, thereby delaying branch formation. In this case, architectural differences between sun- and shade-grown individuals, harvested at the same chronological age, may not represent a functional response to changes in light conditions, but may be a by-product of effects of shade on the rate of plant development. To distinguish between these two alternatives, individuals of the stoloniferous herb Potentilla reptans were subjected to three experimental light conditions: a control treatment providing full daylight, and two shade treatments: neutral shade (13% of ambient PPFD; no changes in light spectral composition) and simulated canopy shade (13% PPFD and a reduced red:far-red ratio). Plant development was followed throughout the experiment by daily monitoring primary stolon growth as well as branch and leaf initiation. Biomass and clonal offspring production were measured when plants were harvested. At the end of the experiment shaded plants had produced significantly fewer branches than clones grown in full daylight. In all three treatments, however, initiation of secondary stolons occurred at the same developmental stage of individual ramets. Shading significantly slowed down the ontogenetic development of plants and this resulted in the observed differences in branching patterns between sun- and shade-grown individuals, when compared at the same chronological age. These results hence provide evidence that shade-induced changes in the branching pattern of clonal plants can be due to purely allometric effects. Implications for interpreting architectural changes in terms of functional shade-avoidance responses are discussed.

１６Ｓ ｒＤＮＡ‐ＲＦＬＰ法による嫌気性処理汚泥中のメタン生成菌の同定

The predominant methanogens in an anaerobic wstewater treatment plant were studied by using a molecular technique without isolation and cultivation. The 16S rRNA genes from the bulk DNA of the anaerobic sludge were amplified by PCR, cloned, and reamplified. Of 30 clones isolated and tested, 24 clones contained a 16S rDNA insert. These positive clones were divided into four ribotypes on the basis of restriction fragment length polymorphism (RFLP) patterns with Hae III. The RFLP pattern of the most abundant ribotype (designated ribotype 1) was almost the same as that of Methanosaeta soehngenii which was computer-predicted and/or experimentally obtained. This was also supported by the results of RFLP analyses with HhaI and SmaI. Phylogenetic trees for methanogens was constructed on the basis of 16S rDNA sequences and 16S rDNA-RFLP patterns. Although there were some differences in branching patterns between the two trees, the RFLP-based tree was suggested to be used roughly as a model showing natural phylogenetic relationships among methanogens. The results of this studyshow that 16S rDNA-KELP analysis with PCR cloning has a promise to identify the predominant methanogens in anaerobic wastewater treatment systems.

Establishment-year height growth in hybrid poplars; relations with longer-term growth

We examined the potential for using components of establishment-year height growth in predicting longer-term growth rankings of six hybrids of Populus deltoides × nigra and one of P. nigra × maximowiczii. Height rankings at the end of the establishment year were correlated (P ≤ 0.10) amongst the four field trials and were generally stable from 38 days after planting onward. End-of-season height rankings from field trials and a controlled environment trial were weakly correlated. Height rankings at the end of the first year did not correlate with rankings at the end of the fifth year, correlations with fifth-year ranks did improve in the second and third years. Shifts in clonal rankings after the establishment year may have been associated with (1) a decreased influence of the planted cutting on growth after the establishment year (2) clonal differences in the time of budburst which were minimized at the time of planting (3) clonal differences in late-season photosynthate allocation to roots (4) clonal differences in branching patterns and canopy development after the establishment year.

Investigations on the nature of a graft-transmissible agent in poinsettia

The free-branching poinsettia (Euphorbia pulcherrima) cultivar Annette Hegg Brilliant Diamond contains a free-branching agent that is graft-transmissible to the restricted-branching cultivar Eckespoint C-1 Red. Transmission electron microscopy failed to reveal evidence of bacteria, fungi, or mycoplasma-like organisms in either 'Brilliant Diamond' or 'C-1 Red' plants. Treatment of both cultivars with tetracycline-hydrochloride produced no differences in branching pattern or leaf morphology in either cultivar, indicating that the agent may not be a mycoplasma-like organism. Scions of a poinsettia mosaic virus indicator species (Euphorbia cyathophora) grafted onto 'Brilliant Diamond' and 'C-1 Red' stocks exhibited the mottling symptoms characteristic of poinsettia mosaic virus, while self-grafted E. cyathophora scions showed no mottling, indicating that poinsettia mosaic virus was not the agent. The agent was not transmitted by pin prick, carborundum, or dodder (Cuscuta sp.), and ribaviran did not eliminate expression of the branching agent from 'Brilliant Diamond' plants. No differences in double-stranded RNA banding patterns were found between extracts of free- and restricted-branching poinsettias by polyacrylamide gel electrophoresis. The double-stranded RNA was attributed to poinsettia mosaic virus and other unknown RNA viruses. Attempts to detect a specific DNA associated with free-branching were inconclusive. Key words: branching agent, Euphorbia pulcherrima, graft transformation, dsRNA, poinsettia mosaic virus.

Plant population studies on peanut (Arachis hypogaea L.) in subtropical Australia. 2. Water-limited conditions

The effects of plant population density on total dry matter (TDM) production, and on pod and kernel yields, of 2 peanut (Arachis hypogaea L.) cultivars (Virginia and Spanish) were investigated under a range of contrasting soil water availability regimes. Protracted crop water deficits were applied to each plant population density treatment in 3 experiments: (i) from planting until the early pod-filling phase (DSWF, dry start, wet finish); (ii) during the pod-filling to maturity phase (WSDF, wet start, dry finish); (iii) from flowering to maturity (TS, terminal stress). Crop water deficits of varying timing and severity were shown to modify substantially the effect of plant population on yield response compared with that observed under well-watered conditions. In most cases, TDM was maximised at the lowest density (40000 Plants/ha). In the WSDF and DSWF experiments, significant cultivar x plant population interactions for pod yield were found. The Spanish cultivar, McCubbin, showed strong pod yield response to S30000 plants/ha, while the Virginia cultivar, Early Bunch, did not respond to increases in plant population above 40000 plants/ha. These differing responses were probably associated with cultivar differences in branching pattern. Under extreme water stress situations where crops were forced to rely solely on soil water reserves (TS), pod yields were highest at the lowest plant population density and declined rapidly as plant population increased. The Gardner and Gardner (1983) model provided a useful framework to characterise the plant population-pod yield response under reduced water availability. The assumptions that both partitioning of dry matter to pods and the hypothetical minimum plant size capable of producing pods were crop constants, irrespective of crop water deficits experienced, were shown to be invalid. These constants may, however, be linearly related to water availability. Relationships relating these parameters to an index of crop or soil water status may improve the predictive capability of the model under water-limited conditions.

The life history in culture of Callithamnion boergesenii sp. nov. (Ceramiaceae, Rhodophyta) from the Caribbean

The widely distributed Caribbean plant presently known as Callithamnion byssoides Arnott ex Harvey in Hooker is here described as C. boergesenii sp. nov. Differences in branching pattern, carposporophyte shape, and spermatangial branch structure distinguish Caribbean material from both eastern and western Atlantic plants referred to C. byssoides. Segregation of the new species is further supported by hybridization experiments. Both eastern and western Atlantic isolates referred to C. byssoides failed to hybridize with C. boergesenii. The new species demonstrated a regular Polysiphonia-type life history in culture.

Size‐related differences in the branching pattern of the motor nerve terminals in triangularis sterni muscle of the mouse

A light microscopy morphometric study was performed in singly innervated synaptic areas of the triangularis sterni muscle of the normal adult Swiss mouse. Investigating mechanisms of the motor nerve growth control, we tested the hypothesis that significant differences in the nerve terminal branching pattern can be detected between different populations of nerve endings classified according to their arborization complexity or size. The main observations of this morphometric study are first, that the mean segment length of the terminal arborization between branch points behaves as an independent variable from the remaining parameters; the mean value of this parameter did not change in nerve endings of differing size and complexity. Secondly, the increase in size of the nerve endings is accompanied by a significant reduction in the mean length of the distal free-end segments. Results are discussed in the context of the possible regulatory mechanisms governing nerve terminal growth and remodelling.

Inter- and intraspecific variation in gorgonian colony morphology: quantifying branching patterns in arborescent animals

Geomorphological methods for quantifying branching networks are used to describe inter- and intra-specific differences in branching patterns among two species of arborescent Caribbean gorgonian, Plexaura homomalla, P. flexuosa, and a third, undescribed plexaurid from the San Blas Islands, Panama. There were significant differences among species for first, second and third order branch lengths, and for tributary to source ratios for first and second order branches. Extrapolations from the branching parameters successfully predicted differences in the branch structure of naturally generated colony fragments. Within P. homomalla, significant differences with depth in the lengths and tributary to source ratios of first, second, and third order branches provide a measure of the greater bushiness of shallow water colonies. These measures can be used to quantify morphological differences in both ecological and systematic analyses. Data on the branching characters of these three gorgonian species demonstrate that gross colony form can be studied as a quantifiable component of phenotype and that gorgonians display both species level and ecophenotypic variation in colony form.

PHENETIC AND CLADISTIC RELATIONSHIPS IN COLLYBIA SECT. LEVIPEDES (FUNGI: BASIDIOMYCETES)

SummaryPhenetic and cladistic methods were both used to study phylogenetic relationships of fungi in the genus Collybia section Levipedes. Ten North American taxa were scored for 23 morphological and ecological traits, and the resulting data set was used for both kinds of analysis. Essentially identical phenograms were generated regardless of the type of similarity or dissimilarity coefficient used. Both principal coordinate and minimum spanning tree analyses also produced results congruent with the various phenograms. For cladistic analysis, parsimony analysis was chosen to construct Wagner trees, which were rooted using several criteria. With only in‐group taxa in the analysis, a single Wagner tree resulted when the dictum ‘common is primitive’ was used to root the tree. Outgroup taxa were chosen from sections Striipedes, Vestipedes and Maculatae. Of the various runs using outgroup taxa from different sections of Collybia, only that with section Striipedes as outgroup resulted in a single unequivocal tree being resolved. This result is consistent with the hypothesis that Striipedes is most closely allied to Levipedes. All parsimony analyses indicated a high level of parallelism in section Levipedes. Both phenetic and cladistic analyses grouped taxa in a similar manner, although several differences in branching pattern were apparent. The C. dryophila complex was clearly distinguished from the rest of the section by all analyses. Other close relationships were suggested between C. alkalivirens and C. fuscopurpurea, and between C. spongiosa and C. kaufmanii. The Wagner trees are presented as hypotheses of phylogenetic relationship in Levipedes.

Structural and antigenic diversity in mucin carbohydrate chains.

There is considerable information on the structure and genetics of the peripheral regions of the complex carbohydrate chains of mucins which vary depending on blood group isotype specificity (1). However, much less is known of the detailed structures and biosynthetic control within the backbone and core regions of these chains. The backbones consist of either Type 1, $$\begin{array}{*{20}c} {{\rm{Ga1\beta 1}} \to {\rm{3G1cNAc\beta 1}} \to, } & {{\rm{or Type 2,}}} & {{\rm{Ga1\beta 1}} \to {\rm{4G1cNAc\beta 1}} \to {\rm{,}}} \\\end{array}$$ sequences (1) and they vary in length and branching. Type 2 sequences in the liner repeating structure $${\rm{Ga1\beta 1}} \to 4{\rm{G1cNAc\beta 1}} \to {\rm{3Ga1\beta 1}} \to {\rm{4G1cNA\beta 1}} \to $$ are recognized by anti-blood group i antibodies (2). Addition of a \({\rm{Ga1\beta 1}} \to 4{\rm{G1cNAc\beta 1}} \to 6\) branch onto the internal galactose of this structure confers blood group I activity (3). Type 1 sequences are apparently not involved in the Ii antigenic system. Species and individual differences in blood group I and i activities may therefore reflect differences in branching patterns and the proportions of Type 1 and Type 2 chain sequences. Ii activities may also be masked by further glycosylation, for example by the addition of sugar residues confering blood group ABH activities.KeywordsBlood GroupCarbohydrate ChainGalactose ResidueGastric MucinMucous GlycoproteinThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

VARIATION OF SHOOT MORPHOLOGY AND BIFURCATION RATIO IN SUGAR MAPLE (ACER SACCHARUM) SAPLINGS

Open‐grown sugar maple saplings differ qualitatively in their gross morphology when compared with saplings growing in shaded forest understories. Forest‐grown saplings have their leaves distributed in a few planar layers, while open‐grown saplings exhibit fuller crowns and more profuse branching. In order to quantify these observed differences in branching patterns, ordering methods were applied to twenty saplings each from forest and open sites. Bifurcation ratio, an index of branching previously assumed to be species constant, differed significantly between forest‐grown and open‐grown saplings. Bifurcation ratios for forest‐grown saplings were low, with a mean of 3.19. Values for open‐grown saplings were generally higher, with a mean of 7.05. This variation of bifurcation ratio between forest‐grown and open‐grown sugar maple saplings is the first such variation within any species to be reported. In addition, open‐grown saplings were characterized by more extension growth of terminal shoots than forest‐grown saplings. These results suggest that sugar maple has a range of branching and light interception characteristics that suit it well in different microenvironments.