Developmental Pattern and Structural Organisation of Leaf Chloroplasts in Lepidozamia peroffskyana

1990 ◽  
Vol 38 (1) ◽  
pp. 53 ◽  
Author(s):  
PM Bonatti ◽  
RB Fornasiero
Keyword(s):  
Leaf Development ◽  
Natural Habitat ◽  
High Ratio ◽  
Light Conditions ◽  
Structural Pattern ◽  
Chl A ◽  
Eastern Australia ◽  
Closed Forest ◽  
Weak Light ◽  
Characteristic Features

The ontogenesis of chloroplasts during leaf development in Lepidozamia peroffskyana Regel is described; this cycad lives in the ground layer of the evergreen subtropical closed forest of south-eastern Australia. Characteristic features in young plastids are long bands of multilayered thylakoids, resembling photosynthetic structures of some green algae and ferns. 'Optional' structures, namely prothylakoid bodies and crystalline inclusions, are present in the pre-grana stages, in relation to the slow rate of leaf development. Mature chloroplasts are characterised by a great number of randomly oriented high grana stacks, a lack of starch, a high ratio of appressed to exposed thylakoids, and a low ratio of Chl a to Chl b; these shade features appear coherent with the natural habitat of Lepidozamia. However, since similar structures have been reported in mature chloroplasts of other cycads living in exposed sites, the existence of a genetically superimposed structural pattern is hypothesised, reflecting a primitive adaptation to weak light conditions of this group of ancient seed plants.

scholarly journals Barking up the right tree: comparative use of arboreal and terrestrial artificial refuges to survey reptiles in temperate eucalypt woodlands

2018 ◽  
Vol 45 (2) ◽  
pp. 185 ◽  
Author(s):  
Damian R. Michael ◽  
Daniel Florance ◽  
Mason Crane ◽  
Wade Blanchard ◽  
David B. Lindenmayer
Keyword(s):  
Survey Methods ◽  
Natural Habitat ◽  
Basal Area ◽  
Agricultural Landscapes ◽  
Mature Trees ◽  
Detection Rates ◽  
Closed Cell ◽  
Eastern Australia ◽  
Non Destructive ◽  
Cell Foam

Context Artificial refuges (cover boards) are a popular method to survey and monitor herpetofauna worldwide. However, one limitation of using artificial refuges in terrestrial environments is the low detection rates of arboreal species. Furthermore, destructive search techniques can damage critical microhabitat such as exfoliating rock or flaking bark of mature trees. Aim We tested a non-destructive, passive method of sampling arboreal reptiles in fragmented agricultural landscapes in south-eastern Australia. Methods We installed 84 artificial bark refuges consisting of strips of non-toxic, closed-cell foam attached to eucalypt trees in 13 patches of remnant vegetation. We used Bayesian statistics to compare differences in detection rates among artificial bark refuges, terrestrial artificial refuges and active searches of natural habitat over a 4-year period. Key results Active searches combined with terrestrial artificial refuges detected the highest number of reptile species, including several cryptic fossorial species. Artificial bark refuges detected, on average, 132 times more individuals of the arboreal southern marbled gecko, Christinus marmoratus, than did terrestrial refuges. Gecko abundance patterns were related to tree characteristics such as tree size, bark thickness and stand basal area, as well as survey year. Conclusions Traditional survey methods such as terrestrial cover boards, in combination with active searches of natural habitat, may significantly underestimate counts for arboreal gecko species. Implications Artificial bark refuges provide a cost-effective, non-destructive and durable method for surveying and monitoring arboreal reptiles in woodland environments over short to medium time frames. Foil-backed, closed-cell foam has broad application for use in spatial capture–recapture studies and long-term monitoring of arboreal reptiles. This method also may be effective for procuring records of threatened arboreal geckos or as a solution for providing temporary habitat in ecological restoration projects.

Environmental response of spring wheat in the south-western Australian cereal belt

1987 ◽  
Vol 38 (4) ◽  
pp. 655 ◽  
Author(s):  
KG Rickert ◽  
RH Sedgley ◽  
WR Stern
Keyword(s):  
Water Use ◽  
Spring Wheat ◽  
Critical Evaluation ◽  
Grain Filling ◽  
High Ratio ◽  
Soil Types ◽  
Environmental Response ◽  
Total Water ◽  
Eastern Australia ◽  
Dry Conditions

The performance of the spring wheat cultivar Gamenya, the leading cultivar in Western Australia since 1968, was studied to identify key aspects of its response to the environment under typically dry conditions on two contrasting soil types: a heavy clay loam and a light loamy sand overlying clay in the Merredin region.In the rain-fed treatments the total water use was similar on both soils and was of the order of 240 mm. On the heavy-textured soil at high nitrogen, the foliage canopy developed more rapidly than on the light soil, resulting in earlier soil water depletion and haying off. Water use efficiencies of about 10 kg grain ha-1 per mm of water were similar to those reported for winter rainfall areas in south-eastern Australia. This suggests a greater degree of buffering against spring drought than is indicated by the high ratio of pre-anthesis to post-anthesis water use (3-4.7:l) relative to values of 2-2.7:l in other parts of the Australian wheatbelt. Data on the partitioning of dry matter indicated that this buffering of the harsh spring conditions at Merredin may be due to a greater contribution of assimilates from pre-anthesis storage, to grain filling. In dry environments, further critical evaluation is needed of the role of stored assimilates in grain formation.Faster canopy closure on the heavy soil resulted from a higher density of shoots and possibly larger leaves. This led to the suggestion that on heavier, more fertile soils, an ideotype with restricted tillering, may be higher yielding. By the end of the season ear bearing shoot densities and total water use were the same on both soil types, thus masking earlier important differences.

scholarly journals In Vitro Enzymatic Activity Assays Implicate the Existence of the Chlorophyll Cycle in Chlorophyll b-Containing Cyanobacteria

2019 ◽  
Vol 60 (12) ◽  
pp. 2672-2683 ◽  
Author(s):  
HyunSeok Lim ◽  
Ayumi Tanaka ◽  
Ryouichi Tanaka ◽  
Hisashi Ito
Keyword(s):  
Enzymatic Activity ◽  
Chlorophyll A ◽  
Developmental Stages ◽  
Enzymatic Activities ◽  
Light Acclimation ◽  
Chlorophyll B ◽  
Light Conditions ◽  
Chl A ◽  
Shallow Seas

Abstract In plants, chlorophyll (Chl) a and b are interconvertible by the action of three enzymes—chlorophyllide a oxygenase, Chl b reductase (CBR) and 7-hydroxymethyl chlorophyll a reductase (HCAR). These reactions are collectively referred to as the Chl cycle. In plants, this cyclic pathway ubiquitously exists and plays essential roles in acclimation to different light conditions at various developmental stages. By contrast, only a limited number of cyanobacteria species produce Chl b, and these include Prochlorococcus, Prochloron, Prochlorothrix and Acaryochloris. In this study, we investigated a possible existence of the Chl cycle in Chl b synthesizing cyanobacteria by testing in vitro enzymatic activities of CBR and HCAR homologs from Prochlorothrix hollandica and Acaryochloris RCC1774. All of these proteins show respective CBR and HCAR activity in vitro, indicating that both cyanobacteria possess the potential to complete the Chl cycle. It is also found that CBR and HCAR orthologs are distributed only in the Chl b-containing cyanobacteria that habitat shallow seas or freshwater, where light conditions change dynamically, whereas they are not found in Prochlorococcus species that usually habitat environments with fixed lighting. Taken together, our results implicate a possibility that the Chl cycle functions for light acclimation in Chl b-containing cyanobacteria.

scholarly journals SWIR AOTF Imaging Spectrometer Based on Single-pixel Imaging

Sensors ◽  
2019 ◽  
Vol 19 (2) ◽  
pp. 390 ◽  
Author(s):  
Huijie Zhao ◽  
Zefu Xu ◽  
Hongzhi Jiang ◽  
Guorui Jia
Keyword(s):  
Mercury Cadmium Telluride ◽  
Short Wave ◽  
Tunable Filter ◽  
Light Conditions ◽  
Acceptance Angle ◽  
Imaging Spectrometer ◽  
Light Passing ◽  
New Type ◽  
Weak Light ◽  
Single Pixel

An acousto-optic tunable filter (AOTF) is a new type of mono-wavelength generator, and an AOTF imaging spectrometer can obtain spectral images of interest. However, due to the limitation of AOTF aperture and acceptance angle, the light passing through the AOTF imaging spectrometer is weak, especially in the short-wave infrared (SWIR) region. In weak light conditions, the noise of a non-deep cooling mercury cadmium telluride (MCT) detector is high compared to the camera response. Thus, effective spectral images cannot be obtained. In this study, the single-pixel imaging (SPI) technique was applied to the AOTF imaging spectrometer, which can obtain spectral images due to the short-focus lens that collects light into a small area. In our experiment, we proved that the irradiance of a short-focus system is much higher than that of a long-focus system in relation to the AOTF imaging spectrometer. Then, an SPI experimental setup was built to obtain spectral images in which traditional systems cannot obtain. This work provides an efficient way to detect spectral images from 1000 to 2200 nm.

Pharmacognostical Evaluation of Raw and Shodhita (Processed) Danti [Baliospermum montanum (Willd.) Muell.-Arg] Root

2017 ◽  
Vol 2 (3) ◽  
pp. 164-174
Author(s):  
Rabinarayan Acharya ◽  
Channappa R Harisha ◽  
Siba P Rout
Keyword(s):  
Image Segmentation ◽  
Reference Material ◽  
Natural Habitat ◽  
Processing Technique ◽  
Scientific Investigation ◽  
Herbal Drug ◽  
Piper Longum ◽  
Characteristic Features ◽  
Fruit Powder

ABSTRACT Introduction Danti, Baliospermum solanifolium (Burm.) Suresh [Syn. Baliospermum montanum (Willd.) Muell. Arg], of family Euphorbiaceae is an important herbal drug in the Ayurveda pharmacopoeia of India. In Ayurveda, Samskara (processing) has been shown to increase the efficacy of various drugs. Shodhana (purificatory measures/processing) is one of the steps involved in Samskara. The Charaka samhita describes the Shodhana (processing) of Danti by applying the fruit powder of Pippali (Piper longum L.) along with honey, wrapping it with Kusha (Desmostachya bippinnata Stapf.), and then fomenting it. The root thus obtained is dried under sunrays and then stored for further use. The exact pharmacognostical changes that transpire through Samskara (classical processing technique) remain to be explored scientifically. Hence, an attempt has been made to evaluate the pharmacognostical changes in Danti root, including its powder microscopy. Materials and methods Roots of raw Danti (RD) were collected from its natural habitat (Odisha) after proper botanical authentication. The roots were subjected to Shodhana and four groups of Danti root—RD, classically processed Danti root (CPDR), Kusha-processed Danti root (KPDR), and water-classically processed Danti root (WPDR)—were obtained. The raw and classically processed Danti roots were evaluated for their macroscopic and microscopic characters while RD, CPDR, KPDR, and WPDR were subjected to powder microscopy. The macroscopic powder images of the respective Danti samples was carried out by L*a*b*color-based image segmentation for identification. Results Transverse sections (TS) of CPDR show characteristic features with multilayered, ruptured reddish cork cells and presence of black debris of Pippali adhering to cork cells. Powder microscopy reveals Pippali with stone cells and dark-brownish oleoresin content in the CPDR group. WPDR reveals more swollen sclereids compared with the KPDR group. Macroscopic imaging showed distinct L*a*b* color-based segmentation. Conclusion Pharmacognostical findings of raw and shodhita Danti root will serve as a reference material for future scientific investigation. How to cite this article Rout SP, Harisha CR, Acharya R. Pharmacognostical Evaluation of Raw and Shodhita (Processed) Danti [Baliospermum montanum (Willd.) Muell.-Arg] Root. J Drug Res Ayurvedic Sci 2017;2(3):164-174.

Population Studies on Acacia melanoxylon R. Br. I. Variation in Seed and Vegetative Characteristics

1978 ◽  
Vol 26 (3) ◽  
pp. 365 ◽  
Author(s):  
TP Farrell ◽  
DH Ashton
Keyword(s):  
Environmental Parameters ◽  
Morphological Characters ◽  
Annual Rainfall ◽  
Clinal Variation ◽  
Acacia Melanoxylon ◽  
Open Forest ◽  
Popu Lations ◽  
Eastern Australia ◽  
Closed Forest ◽  
Shape And Size

Considerable variation in phyllode shape and size was found between populations of Acacia melanoxylon sampled over the wide geographical range (27° of latitude) of this species in tropical and temperate eastern Australia. Communities sampled range from closed-forest to open-forest and grassy woodland. Some evidence of relationships between morphological characters of the phyllodes and environ- mental conditions of the collecting site was found, although such relationships are complex and not easily understood. The most important factors determining phyllode shape and size were the distance of the collecting site from the coast, and the seasonal distribution of the annual rainfall. Phyllodes tended to be smaller and more symmetric in the drier inland areas. Differences were found between seed characteristics of selected populations, although there was no evidence of correlation of these with selected environmental parameters. Seedlings of 17 popu- lations of A. melanoxylon grown under uniform glasshouse conditions showed some differences in leaf morphology. The age at which conversion to phyllodes begins is correlated with the mean annual rainfall at the site of origin of the seeds. The occurrence of this species in such a wide variety of habitats in eastern Australia is probably due to its clinal variation.

scholarly journals Interactive effects of temperature and light during deep convection: a case study on growth and condition of the diatom Thalassiosira weissflogii

2014 ◽  
Vol 72 (6) ◽  
pp. 2061-2071 ◽  
Author(s):  
B. Walter ◽  
J. Peters ◽  
J. E. E. van Beusekom ◽  
M. A. St. John
Keyword(s):  
Primary Production ◽  
Deep Convection ◽  
Growth Conditions ◽  
Interactive Effects ◽  
Light Conditions ◽  
Thalassiosira Weissflogii ◽  
Pulsed Light ◽  
Low Light ◽  
Chl A ◽  
The North

Abstract Aim of this study was to expose phytoplankton to growth conditions simulating deep winter convection in the North Atlantic and thereby to assess changes in physiology enabling their survival. Growth rate, biochemical composition, and photosynthetic activity of the diatom Thalassiosira weissflogii were determined under two different light scenarios over a temperature range of 5–15°C to simulate conditions experienced by cells during winter deep convection. These metrics were examined under a low light scenario (20 µmol m−2 s−1, 12/12 h light/dark), and compared with a scenario of short light pulses of a higher light intensity (120 µmol m−2 s−1, 2/22 h light/dark). Both experimental light conditions offered the same daily light dose. No growth was observed at temperatures below 8°C. Above 8°C, growth rates were significantly higher under low light conditions compared with those of short pulsed light exposures, indicating a higher efficiency of light utilization. This could be related to (i) a higher content of Chl a per cell in the low light trial and/or (ii) a more efficient transfer of light energy into growth as indicated by constantly low carbohydrate levels. In contrast, pulsed intense light led to an accumulation of carbohydrates, which were catabolized during the longer dark period for maintaining metabolism. Light curves measured via Chl a fluorescence indicated low light assimilation for the algae exposed to short pulsed light. We postulate that our trial with short light pluses did not provide sufficient light to reach full light saturation. In general, photosynthesis was more strongly affected by temperature under pulsed light than under low light conditions. Our results indicate that model estimates of primary production in relation to deep convection, which are based on average low light conditions, not considering vertical transportation of algae will lead to an overestimation of in situ primary production.

scholarly journals The history and natural regeneration of a secondary oak-beech woodland on a former wood-pasture in Hungary

2015 ◽  
Vol 84 (2) ◽  
pp. 215-225 ◽  
Author(s):  
Anna Varga ◽  
Péter Ódor ◽  
Zsolt Molnár ◽  
János Bölöni
Keyword(s):  
Stand Structure ◽  
Tree Stand ◽  
Wood Pasture ◽  
Continuous Forest ◽  
Forestry Management ◽  
Large Trees ◽  
Closed Forest ◽  
Tree Stand Structure ◽  
Characteristic Features ◽  
Agricultural Areas

Characteristic features of European woodland include both a reduction in natural forest areas and an increase in former agricultural areas occupied by secondary woodland. The management of these areas is challenging in terms of nature conservation, agricultural and forestry management and policy. The aim of our study was to reconstruct the history and to document the current tree stand structure for a secondary oak-beech woodland in Hungary. Towards the end of the 1800s, this area which was once almost completely occupied by a continuous forest, had been transformed into a wood-pasture. As a result of its gradual abandonment, the closed forest stand of the pasture increased from 10 to 52% between 1963 and 2005. The most characteristic feature of this woodland is the abundance of large trees. Globally, the number of large and ancient trees is rapidly diminishing. Therefore preserving and maintaining such areas, where large trees could live, is an essential management task.

Sign in / Sign up

Export Citation Format

Share Document