scholarly journals Chloroplast Distribution in the Stems of 23 Eucalypt Species

Plants ◽  
2020 ◽  
Vol 9 (12) ◽  
pp. 1814
Author(s):  
Geoffrey E. Burrows ◽  
Celia Connor
Keyword(s):  
Woody Plants ◽  
Secondary Xylem ◽  
Narrow Band ◽  
Large Diameter ◽  
Small Diameter ◽  
High Density ◽  
Outer Bark ◽  
Leaf Mesophyll ◽  
Eucalypt Species ◽  
Wide Range

Small diameter branchlets and smooth barked stems and branches of most woody plants have chloroplasts. While the stems of several eucalypt species have been shown to photosynthesise, the distribution of chloroplasts has not been investigated in detail. The distribution of chloroplasts in branchlets (23 species) and larger diameter stems and branches with smooth bark (14 species) was investigated in a wide range of eucalypts (species of Angophora, Corymbia and Eucalyptus) using fresh hand sections and a combination of bright field and fluorescence microscopy. All species had abundant stem chloroplasts. In both small and large diameter stems, the greatest concentration of chloroplasts was in a narrow band (usually 100–300 μm thick) immediately beneath the epidermis or phellem. Deeper chloroplasts were present but at a lower density due to abundant fibres and sclereids. In general, chloroplasts were found at greater depths in small diameter stems, often being present in the secondary xylem rays and the pith. The cells of the chlorenchyma band were small, rounded and densely packed, and unlike leaf mesophyll. A high density of chloroplasts was found just beneath the phellem of large diameter stems. These trees gave no external indication that green tissues were present just below the phellem. In these species, a thick phellem was not present to protect the inner living bark. Along with the chlorenchyma, the outer bark also had a high density of fibres and sclereids. These sclerenchyma cells probably disrupted a greater abundance and a more organised arrangement of the cells containing chloroplasts. This shows a possible trade-off between photosynthesis and the typical bark functions of protection and mechanical strength.

Comparative developmental anatomy of the taproot of the cucurbitaceous vines Citrullus colocynthis (perennial), Citrullus lanatus (annual) and Cucumis myriocarpus (annual)

2014 ◽  
Vol 62 (7) ◽  
pp. 537 ◽  
Author(s):  
Geoffrey E. Burrows ◽  
Razia S. Shaik
Keyword(s):  
Secondary Xylem ◽  
Citrullus Lanatus ◽  
Large Diameter ◽  
Small Diameter ◽  
Low Density ◽  
Citrullus Colocynthis ◽  
Xylem Parenchyma ◽  
Developmental Anatomy ◽  
Ray Parenchyma ◽  
Ecological Differences

The genus Citrullus (Cucurbitaceae) consists of four species of desert vines. Two species (Citrullus colocynthis and Citrullus lanatus) are widespread weeds on several continents. Above ground, they can be relatively difficult to distinguish apart. However, Citrullus colocynthis is a perennial with a tuberous taproot, whereas Citrullus lanatus is an annual with a slender taproot. We studied the morphology and anatomy of taproot development to better understand their structural and ecological differences. The annual Citrullus lanatus reached close to its maximum taproot diameter (~3 mm) soon after germination. The vascular cambium formed four relatively broad triangular sectors of fibres in which were embedded relatively large diameter vessels. These sectors were separated by narrower triangular areas of secondary ray parenchyma. In contrast, the taproot diameter of the perennial Citrullus colocynthis continued to increase during the study, reaching ~20 mm after 14 weeks. Most of this substantial root consisted of secondary xylem parenchyma, with a low density of relatively small diameter vessels and few fibres. The remarkable differences in root morphology and anatomy of the studied species of Citrullus are related to differences in their annual and perennial lifecycles. Interestingly, the slender taproots of Citrullus lanatus were calculated to have a similar theoretical hydraulic conductance to that of Citrullus colocynthis (large diameter taproot).

Comparison of hairtube types for the detection of mammals

1999 ◽  
Vol 26 (6) ◽  
pp. 745 ◽  
Author(s):  
D. B. Lindenmayer ◽  
R. D. Incoll ◽  
R. B. Cunningham ◽  
M. L. Pope ◽  
C. F. Donnelly ◽  
...  
Keyword(s):  
Large Diameter ◽  
Small Diameter ◽  
Detection Rates ◽  
South Wales ◽  
Wide Range ◽  
Mountain Ash ◽  
Common Wombat ◽  
Antechinus Stuartii ◽  
Pvc Pipe ◽  
The One

We compare detection rates of different species of mammals by three types of hairtubes in both the mountain ash forests of the central highlands of Victoria and a range of wet forest types at Tumut in southern New South Wales. The types of hairtubes were a small-diameter PVC pipe, a large-diameter PVC pipe and a newly constructed tapered hair funnel. Data were analysed for brown antechinus (Antechinus stuartii), bush rat (Rattus fuscipes), common wombat (Vombatus ursinus), swamp wallaby (Wallabia bicolor) and common and mountain brushtail possums (Trichosurus vulpecula and T. caninus). The most effective hairtube type (i.e. the one yielding the highest number of detections) varied between species: small hairtubes forR. fuscipes, hair funnels for Trichosurus spp., and large hairtubes for V. ursinus and W. bicolor. For A. stuartii, the most effective hairtube type differed between the two study regions (hair funnels in Victoria and small hairtubes at Tumut). Detection by more than one hairtube type at a given plot was uncommon. Our findings have important implications for field surveys and how data gathered from such studies are interpreted. For example, if the aim of field survey is to detect a wide range of species then several types of hairtubes may need to be deployed.

Examining the Anomalous Electrical Characteristics Observed in InN Nanowires

2008 ◽  
Vol 8 (1) ◽  
pp. 222-227 ◽  
Author(s):  
Anurag Chaudhry ◽  
M. Saif Islam
Keyword(s):  
Large Diameter ◽  
Small Diameter ◽  
Photonic Devices ◽  
High Density ◽  
Conduction Path ◽  
Accumulation Layer ◽  
Electron Accumulation ◽  
Unique Material ◽  
Measured Resistance ◽  
Surface Conduction

Research interest in InN has intensified in recent years because of its unique material properties and promising applications in electronic and photonic devices. Measurements on InN nanowires presented by Chang et al., [J. Electron. Mater. 35, 738 (2006)] showed an anomalous resistance behavior in InN nanowires with diameters less than 90 nm. We examine possible theories presented in literature to explain this intriguing observation. We propose that the presence of a high density electron accumulation layer at the surface of thin InN nanowires is the most probable cause for the uncharacteristic relationship between the total measured resistance and the ratio of length-to-area. High density surface electron accumulation layer, characteristic of InN films and nanowire, promotes a surface conduction path distinct from the bulk conduction. For large diameter nanowires, bulk conduction is likely to be the dominant mechanism while surface conduction is proposed to play a major role for small diameter InN nanowires.

Buds, bushfires and resprouting in the eucalypts

2013 ◽  
Vol 61 (5) ◽  
pp. 331 ◽  
Author(s):  
G. E. Burrows
Keyword(s):  
Phylogenetic Analysis ◽  
Leaf Area ◽  
High Intensity ◽  
Structural Damage ◽  
Large Diameter ◽  
Small Diameter ◽  
Subsequent Development ◽  
Degree Of Protection ◽  
Wide Range ◽  
Large Genus

Eucalypts encounter a wide range of severe disturbances such as extensive defoliation by insects, major structural damage from cyclonic winds, as well as foliage and bark loss during drought and fire. Most healthy, mature eucalypts are not killed by these events, but regenerate vegetatively. With increasing intensity of disturbance, resprouting first occurs from the accessory buds in the small-diameter branchlets of the crown, followed by the epicormic buds in the medium- and large-diameter branches and stems, and then from the buds of the lignotuber. All these modes of regeneration are ultimately dependent on preventitious buds and, thus, the present review concentrates on axillary buds, their subsequent development into epicormic or lignotuber buds and their degree of protection from fire. The eucalypts have remarkably abundant, well protected and anatomically distinctive bud-forming structures in their leaf axils, branches, stems and lignotubers. These structures are quite consistent across this large genus, but are generally different from resprouting structures in many other plants. From an anatomical perspective, these structures seem best adapted to regeneration after fire, rather than damage from insects, storms or drought and this also correlates with ecological observations. On a worldwide basis, the eucalypts are some of the most successful post-fire resprouters, especially epicormic resprouting after medium- and high-intensity fires. Given the apparent ecological advantages of epicormic resprouting (the rapid reestablishment of extensive leaf area while simultaneously shading basal resprouters and seedlings) this could be an important factor in the success of eucalypts in Australia. Recent phylogenetic analysis has indicated a long relationship between eucalypts, fire and bud structures that facilitate resprouting.

scholarly journals Modeling benzene permeation through drinking water high density polyethylene (HDPE) pipes

2015 ◽  
Vol 13 (3) ◽  
pp. 758-772 ◽  
Author(s):  
Feng Mao ◽  
Say Kee Ong ◽  
James A. Gaunt
Keyword(s):  
Drinking Water ◽  
High Density Polyethylene ◽  
Distribution Systems ◽  
Water Distribution ◽  
Large Diameter ◽  
Small Diameter ◽  
High Density ◽  
Ethyl Benzene ◽  
Constant Input ◽  
Hdpe Pipes

Organic compounds such as benzene, toluene, ethyl benzene and o-, m-, and p-xylene from contaminated soil and groundwater may permeate through thermoplastic pipes which are used for the conveyance of drinking water in water distribution systems. In this study, permeation parameters of benzene in 25 mm (1 inch) standard inside dimension ratio (SIDR) 9 high density polyethylene (HDPE) pipes were estimated by fitting the measured data to a permeation model based on a combination of equilibrium partitioning and Fick's diffusion. For bulk concentrations between 6.0 and 67.5 mg/L in soil pore water, the concentration-dependent diffusion coefficients of benzene were found to range from 2.0 × 10−9 to 2.8 × 10−9cm2/s while the solubility coefficient was determined to be 23.7. The simulated permeation curves of benzene for SIDR 9 and SIDR 7 series of HDPE pipes indicated that small diameter pipes were more vulnerable to permeation of benzene than large diameter pipes, and the breakthrough of benzene into the HDPE pipe was retarded and the corresponding permeation flux decreased with an increase of the pipe thickness. HDPE pipes exposed to an instantaneous plume exhibited distinguishable permeation characteristics from those exposed to a continuous source with a constant input. The properties of aquifer such as dispersion coefficients (DL) also influenced the permeation behavior of benzene through HDPE pipes.

An anatomical study of epicormic bud strand structure in Eucalyptus cladocalyx (Myrtaceae)

2000 ◽  
Vol 48 (2) ◽  
pp. 233 ◽  
Author(s):  
G. E. Burrows
Keyword(s):  
Transverse Section ◽  
Secondary Xylem ◽  
Large Diameter ◽  
Anatomical Study ◽  
Leaf Primordia ◽  
Bark Thickness ◽  
Outer Bark ◽  
Epicormic Shoots ◽  
Vascular Connections ◽  
Do So

Epicormic bud strands in Eucalyptus cladocalyx F.Muell. extended from the pith to the outer bark. In large-diameter stems (30 cm diameter, 2 cm bark thickness) the epicormic bud strands had their greatest anatomical complexity at the level of the vascular cambium. At this level the epicormic bud strand was about 3 mm wide × 5 mm high in transverse section and within it were 22–40 radially arranged strips of cells of meristematic appearance embedded in a mainly parenchymatous matrix. Well-developed buds with leaf primordia and vascular connections were never observed in intact trees, although when stimulated each meristem strip could produce numerous bud primordia. Toward the bark surface the epicormic bud strands became progressively simpler in structure. On the stem surface, the position of the epicormic bud strand was shown by a number of adjacent small protrusions which appeared to have no meristematic potential. From the outer secondary xylem to the pith the bud strand usually became slightly smaller in diameter and its cells, although nucleated, had thick lignified walls and the meristem strips were much reduced or were not present. In most previously investigated angiosperm tree genera epicormic shoots develop from suppressed buds embedded in the bark. Eucalyptus appears to be unique in that suppressed buds are not present in the bark and that each epicormic bud strand has the potential to form numerous bud primordia when stimulated to do so.

Differences in the brain stem terminations of large- and small-diameter vestibular primary afferents

1995 ◽  
Vol 74 (3) ◽  
pp. 1362-1366 ◽  
Author(s):  
J. A. Huwe ◽  
E. H. Peterson
Keyword(s):  
Brain Stem ◽  
Large Diameter ◽  
Small Diameter ◽  
Movement Control ◽  
Three Dimensions ◽  
Significant Shift ◽  
Axon Diameter ◽  
Vestibular Complex ◽  
The Brain ◽  
Adjacent Brain

1. We visualized the central axons of 32 vestibular afferents from the posterior canal by extracellular application of horseradish peroxidase, reconstructed them in three dimensions, and quantified their morphology. Here we compare the descending limbs of central axons that differ in parent axon diameter. 2. The brain stem distribution of descending limb terminals (collaterals and associated varicosities) varies systematically with parent axon diameter. Large-diameter afferents concentrate their terminals in rostral regions of the medial/descending nuclei. As axon diameter decreases, there is a significant shift of terminal concentration toward the caudal vestibular complex and adjacent brain stem. 3. Rostral and caudal regions of the medial/descending nuclei have different labyrinthine, cerebellar, intrinsic, commissural, and spinal connections; they are believed to play different roles in head movement control. Our data help clarify the functions of large- and small-diameter afferents by showing that they contribute differentially to rostral and caudal vestibular complex.

scholarly journals Metabolic engineering in woody plants: challenges, advances, and opportunities

aBIOTECH ◽  
2021 ◽  
Author(s):  
Shu Yu ◽  
Cody S. Bekkering ◽  
Li Tian
Keyword(s):  
Renewable Energy ◽  
Metabolic Engineering ◽  
Ecosystem Services ◽  
Plant Transformation ◽  
Woody Plants ◽  
Woody Plant ◽  
High Biomass ◽  
Generation Times ◽  
Wide Range ◽  
Biochemical Diversity

AbstractWoody plant species represent an invaluable reserve of biochemical diversity to which metabolic engineering can be applied to satisfy the need for commodity and specialty chemicals, pharmaceuticals, and renewable energy. Woody plants are particularly promising for this application due to their low input needs, high biomass, and immeasurable ecosystem services. However, existing challenges have hindered their widespread adoption in metabolic engineering efforts, such as long generation times, large and highly heterozygous genomes, and difficulties in transformation and regeneration. Recent advances in omics approaches, systems biology modeling, and plant transformation and regeneration methods provide effective approaches in overcoming these outstanding challenges. Promises brought by developments in this space are steadily opening the door to widespread metabolic engineering of woody plants to meet the global need for a wide range of sustainably sourced chemicals and materials.

scholarly journals Elastic Modulus and Elasticity Ratio of Malignant Breast Lesions with Shear Wave Ultrasound Elastography: Variations with Different Region of Interest and Lesion Size

Diagnostics ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1015
Author(s):  
Antonio Bulum ◽  
Gordana Ivanac ◽  
Eugen Divjak ◽  
Iva Biondić Špoljar ◽  
Martina Džoić Dominković ◽  
...  
Keyword(s):  
Elastic Modulus ◽  
Shear Wave ◽  
Large Diameter ◽  
Small Diameter ◽  
Shear Wave Elastography ◽  
Lesion Size ◽  
Ultrasound Elastography ◽  
Breast Lesions ◽  
Malignant Breast ◽  
The Impact

Shear wave elastography (SWE) is a type of ultrasound elastography with which the elastic properties of breast tissues can be quantitatively assessed. The purpose of this study was to determine the impact of different regions of interest (ROI) and lesion size on the performance of SWE in differentiating malignant breast lesions. The study included 150 female patients with histopathologically confirmed malignant breast lesions. Minimal (Emin), mean (Emean), maximal (Emax) elastic modulus and elasticity ratio (e-ratio) values were measured using a circular ROI size of 2, 4 and 6 mm diameters and the lesions were divided into large (diameter ≥ 15 mm) and small (diameter < 15 mm). Highest Emin, Emean and e-ratio values and lowest variability were observed when using the 2 mm ROI. Emax values did not differ between different ROI sizes. Larger lesions had significantly higher Emean and Emax values, but there was no difference in e-ratio values between lesions of different sizes. In conclusion, when measuring the Emin, Emean and e-ratio of malignant breast lesions using SWE the smallest possible ROI size should be used regardless of lesion size. ROI size has no impact on Emax values while lesion size has no impact on e-ratio values.

Bark in Woody Plants: Understanding the Diversity of a Multifunctional Structure

2019 ◽  
Vol 59 (3) ◽  
pp. 535-547 ◽  
Author(s):  
Julieta A Rosell
Keyword(s):  
Woody Plants ◽  
Fire Regime ◽  
Soluble Sugars ◽  
Plant Performance ◽  
Functional Ecology ◽  
Bark Thickness ◽  
Outer Bark ◽  
Plant Parts ◽  
Selective Forces ◽  
Plant Ecological

Abstract Most biological structures carry out multiple functions. Focusing on only one function to make adaptive inferences overlooks that manifold selection pressures and tradeoffs shape the characteristics of a multifunctional structure. Focusing on single functions can only lead to a partial picture of the causes underlying diversity and the evolutionary origin of the structure in question. I illustrate this discussion using bark as a study case. Bark comprises all the tissues surrounding the xylem in woody plants. Broadly, bark includes an inner and mostly living region and an outer, dead one. Of all plant structures, bark has the most complex anatomical structure and ontogenetic origin involving two (and often three) different meristems. Traditionally, the wide diversity in bark traits, mainly bark thickness, has been interpreted as the result of the selective pressures imposed by fire regime. However, recent research has shown that explanations based on fire regime cannot account for salient patterns of bark variation globally including the very strong inner bark thickness–stem diameter scaling, which is likely due to metabolic needs, and the very high intracommunity variation in total, inner, and outer bark thickness, and in inner:outer proportions. Moreover, explanations based on fire disregard that in addition to fire protection, bark carries out several other crucial functions for plants including translocation of photosynthates; storage of starch, soluble sugars, water, and other compounds; protection from herbivores, pathogens, and high temperatures; wound closure, as well as mechanical support, photosynthesis, and likely being involved in xylem embolism repair. All these functions are crucial for plant performance and are involved in synergistic (e.g., storage of water and insulation) and trade-off relationships (e.g., protection from fire vs photosynthetic activity). Focusing on only one of these functions, protection from fire has provided an incomplete picture of the selective forces shaping bark diversity and has severely hindered our incipient understanding of the functional ecology of this crucial region of woody stems. Applying a multifunctional perspective to the study of bark will allow us to address why we observe such high intracommunity variation in bark traits, why some bark trait combinations are ontogenetically impossible or penalized by selection, how bark is coordinated functionally with other plant parts, and as a result, to understand how bark contributes to the vast diversity of plant ecological strategies across the globe.

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