On the Ecology of Larvae of Anopheles culicifacies Giles, in Borrow-pits

(1) In seepage-filled borrow-pits in South India it was observed that there was a progressive decline in the density of larvae of Anopheles culicifacies, Giles, as the pits became older. The largest numbers of larvae were tound soon after water entered the newly-dug pits.(2) There was less ovipositing by culicifacies in older pits than in new ones dug late in the irrigation season. Newer pits seemed definitely more attractive in this species than older ones. These newer pits sheltered more culicifacies larvae late in the season than the older pits.(3) The decline of culicifacies larva density in a borrow-pit seemed to be due mainly to factors internal to the pits. There was no evidence of the influence of external factors, except from October to January, when perhaps meteorological influences supplemented the internal factors. The attractiveness of new borrow-pits to culicifacies appeared to be due mainly to internal factors.(4) Certain simple factors studied did not seem to have any significance in relation to culicifacies density in the pits. Rainfall, predators, macroscopic vegetation, pH, CO2, dissolved oxygen, bicarbonate alkalinity, ratio of free to bound and half bound CO2, hardness, chlorine, ammoniacal nitrogen, nitrates, nitrites, sulfates and iron, appeared to have no significance in this regard. Albuminoid nitrogen and oxygen absorbed perhaps had some significance, which was not clear.(5) Among planktonic organisms, the individual groups of organisms, such as green algae, diatoms, rotifers, and copepods, definitely showed no relation to culicifacies breeding. Protozoa as a group appeared to be negatively associated to a slight degree. Blue-green algae also seemed to have a negative association.(6) Amorphous organic matter and total plankton, however, showed statistically significant negative association with larval density of culicifacies The decline in culicifacies larvae was clearly associated with increase in total plankton and amorphous matter. The attractiveness of new borrow-pits also seemed to be related to their low total plankton content.(7) The exact manner in which the total organic matter acted as an inhibitory factor against culicifacies breeding was not determined.

Download Full-text

Variable Amounts of Dna Related to the size of Chloroplasts

Journal of Cell Science ◽

10.1242/jcs.11.2.357 ◽

1972 ◽

Vol 11 (2) ◽

pp. 357-377

Author(s):

K. V. KOWALLIK ◽

R. G. HERRMANN

Keyword(s):

Chloroplast Dna ◽

Beta Vulgaris ◽

Green Algae ◽

Developmental State ◽

Biochemical Data ◽

Serial Sections ◽

Blue Green Algae ◽

The Individual ◽

Dna Amounts

Glutaraldehyde-fixed strips of fully differentiated leaves of Beta vulgaris L. were treated with proteases. With this method it is possible to display DNA-regions in chloroplasts selectively and to reconstruct them from serial sections. As in young plastids, the DNA in mature plastids is also distributed within several regions which are separated rather clearly by thylakoids. The number of such regions depends upon the size of the organelle and thus upon its developmental state. The shape of the regions is, in contrast to less-differentiated plastids, mostly elongated. The individual regions seem to contain unequal quantities of DNA-fibrils. A comparison of our ultrastructural results and biochemical data (DNA-amounts per plastid depending on the size of the organelle; kinetic complexity of chloroplast-DNA of Beta) as well as a comparison of the chloroplast with similar prokaryotic systems (as in bacteria, blue-green algae, and mitochondria) leads to the suggestion that each DNA-containing region can be regarded as a single nucleoid. In addition, each nucleoid already contains several (on average, 4-8) genetic units. Thus the chloroplast of Beta seems genetically polyvalent in at least 2 respects: (i) it is of polyenergidic organization, and (ii) the individual nucleoids can be polyploid to varying degrees.

Download Full-text

Effects of Potassium Permanganate Preoxidation Followed with Coagulation on the Fluorescence Spectrum of Algae

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.71-78.2920 ◽

2011 ◽

Vol 71-78 ◽

pp. 2920-2924 ◽

Cited By ~ 1

Author(s):

Peng Chao Xie ◽

Jing Yun Fang ◽

Jun Ma

Keyword(s):

Organic Matter ◽

Fluorescence Spectrum ◽

Potassium Permanganate ◽

Green Algae ◽

Fluorescence Intensity ◽

Fluorescence Spectra ◽

Organic Matters ◽

Blue Green Algae ◽

Kind Of Blue

This study was performed to illustrate the effects of preoxidation by potassium permanganate on the fluorescence spectrum of Microcysis aeruginosa, a kind of blue-green algae. The results showed there were four dominate excitation/emission (Ex/Em) wavelength pairs, 230/334, 280/312, 280/334 and 620/642 nm/nm in the fluorescence spectra of algae and their derived organic matters (AOM). Coagulation resulted in desorption of the organic matter adsorbed in algae cells and produced two new fluorophores centered at 275/460 and 400/460 nm/nm. Potassium permanganate preoxidation could reduce the fluorescence intensity of algae and dissolved algal organic matters effectively and the descent rate increased with increasing potassium permanganate dosage.

Download Full-text

Geobiology of the Paleoproterozoic Belcher Group, Nunavut, Canada

USURJ University of Saskatchewan Undergraduate Research Journal ◽

10.32396/usurj.v6i1.507 ◽

2020 ◽

Vol 6 (1) ◽

Author(s):

Zach Pollock ◽

Camille Partin

Keyword(s):

Raman Spectroscopy ◽

Organic Matter ◽

North America ◽

Green Algae ◽

Photoelectron Spectroscopy ◽

Iron Formation ◽

Hudson Bay ◽

X Ray ◽

Blue Green Algae ◽

Eukaryotic Organisms

The ~2.0-1.8 Ga (billion years old) Belcher Group on the Belcher Islands in Nunavut provide a unique opportunity for studying Paleoproterozoic geobiology. The Belcher Group includes a sequence of low metamorphic grade peritidal carbonate rocks that preserve putative microbiota, as first described by Hofmann and Jackson (1969). Microbial mats, including stromatolites, are abundant in the peritidal carbonate succession. Additionally, morphologies possibly related to blue-green algae were first described in granular iron formation rocks of the Belcher Group by Moore (1918). The Belcher Group microbiota are a group of simple organisms, believed to be prokaryotic in nature. Microbiota morphologies include ellipsoids, spheroids, and filamentous chains of cells interpreted by previous workers to represent blue-green algae and acritarchs. Some microstructures are questionably biogenic and might be abiotic. The most significant field studies on the Belcher Group occurred from the late 1950s to the early 1980s, which provides the geological context for this study. This project aims to build on the previous work of H. Hofmann and others in the ‘60s and bring these microbiota into a modern context, drawing on the analytical advancements of the last 50 years. The main goal of the project is to determine if there is evidence that the microbiota are perhaps eukaryotic organisms. The emergence of eukaryotes is arguably the most significant geobiological event in Earth history, with eukaryotic cells believed to have evolved around 1.6 Ga (Knoll et al. 2006; Javaux and Lepot 2018), but some contentious fossils interpreted to represent eukaryotes have been dated to as early as 2.2 Ga (Retallack et al. 2013). In North America, the oldest discovered eukaryotic remains are around 1.5 Ga (Adam et al. 2017). If eukaryotic fossils were to be discovered in the Belcher Group, this would make them the oldest occurrence in North America. To test the hypothesis, samples from the microbiota-containing units were collected on the Belcher Islands. Both light microscopy and a collection of modern analytical techniques will be used to obtain high resolution images and chemical signatures of the microbiota and their biosignatures. Preliminary data from petrography, Raman Spectroscopy, and X-ray Photoelectron Spectroscopy (XPS) will be presented. Both Raman spectroscopy and XPS have been used as characterization tools in other studies looking at microbiota and organic matter remains (Qu et al. 2018; Arnarson and Keil 2001). Raman collects molecular and structural data from the sample, while XPS collects elemental chemical data. Both techniques are therefore particularly useful for identifying and characterizing organic carbon, which is the base of organic matter. References: Adam, Zachary R., Mark L. Skidmore, David W. Mogk, and Nicholas J. Butterfield. 2017. “A Laurentian Record of the Earliest Fossil Eukaryotes.” Geology 45 (5): 387–90. https://doi.org/10.1130/G38749.1. Arnarson, Thorarinn S., and Richard G. Keil. 2001. “Organic–Mineral Interactions in Marine Sediments Studied Using Density Fractionation and X-Ray Photoelectron Spectroscopy.” Organic Geochemistry 32 (12): 1401–15. https://doi.org/10.1016/S0146-6380(01)00114-0. Hofmann, H. J., and G. D. Jackson. 1969. “Precambrian (Aphebian) Microfossils from Belcher Islands, Hudson Bay.” Canadian Journal of Earth Sciences 6 (5): 1137–44. https://doi.org/10.1139/e69-115. Javaux, Emmanuelle J., and Kevin Lepot. 2018. “The Paleoproterozoic Fossil Record: Implications for the Evolution of the Biosphere during Earth’s Middle-Age.” Earth-Science Reviews 176 (January): 68–86. https://doi.org/10.1016/j.earscirev.2017.10.001. Knoll, A.H, E.J Javaux, D Hewitt, and P Cohen. 2006. “Eukaryotic Organisms in Proterozoic Oceans.” Philosophical Transactions of the Royal Society B: Biological Sciences 361 (1470): 1023–38. https://doi.org/10.1098/rstb.2006.1843. Moore, E. S. 1918. “The Iron-Formation on Belcher Islands, Hudson Bay, with Special Reference to Its Origin and Its Associated Algal Limestones.” The Journal of Geology 26 (5): 412–38. Qu, Yuangao, Shixing Zhu, Martin Whitehouse, Anders Engdahl, and Nicola McLoughlin. 2018. “Carbonaceous Biosignatures of the Earliest Putative Macroscopic Multicellular Eukaryotes from 1630 Ma Tuanshanzi Formation, North China.” Precambrian Research 304 (January): 99–109. https://doi.org/10.1016/j.precamres.2017.11.004. Retallack, Gregory J., Evelyn S. Krull, Glenn D. Thackray, and Dula Parkinson. 2013. “Problematic Urn-Shaped Fossils from a Paleoproterozoic (2.2Ga) Paleosol in South Africa.” Precambrian Research 235 (September): 71–87. https://doi.org/10.1016/j.precamres.2013.05.015.

Download Full-text

5. Microbial engines of the coral reef

Coral Reefs: A Very Short Introduction ◽

10.1093/actrade/9780198869825.003.0005 ◽

2021 ◽

pp. 58-67

Author(s):

Charles Sheppard

Keyword(s):

Organic Matter ◽

Coral Reef ◽

Organic Compounds ◽

Green Algae ◽

Major Part ◽

Food Chains ◽

Primary Producers ◽

Blue Green Algae ◽

Form Part ◽

Species Groups

The symbiosis between corals and the dinoflagellates—zooxanthellae—is the key to a tight recycling of nutrients on reefs that generally thrive best in nutrient poor parts of the oceans. But several other mechanisms and species groups aid transmission of organic matter and energy along the numerous food chains of a reef. Viruses, bacteria, and archaea are key to the recycling of carbon and organic compounds, making the ‘microbial loop’, one key but invisible aspect to how the reef functions. Cyanobacteria, formerly blue-green algae, are a major part of the micro-benthos too, and are important primary producers. Protists are also hugely abundant—larger, single-celled organisms which are eukaryotes with cells with nuclei, and this group has species that exist in planktonic and benthic forms. Foraminifera are important protists, being abundant and having calcareous tests, so that they are significant sand producers in some areas. Finally, zooplankton provide food for numerous reef species, and indeed larvae from all species form part of the plankton temporarily too.

Download Full-text

Freeze-Fracture Replication in the Ultrastructure of Blue-Green Algae

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100060386 ◽

1967 ◽

Vol 25 ◽

pp. 74-75

Author(s):

L. V. Leak

Keyword(s):

Cell Wall ◽

Electron Microscope ◽

Green Algae ◽

Three Dimensional ◽

Freeze Fracture ◽

Electron Microscopic ◽

Photosynthetic Membranes ◽

Blue Green Algae ◽

Cell Biol ◽

Cellular Components

Electron microscopic observations of freeze-fracture replicas of Anabaena cells obtained by the procedures described by Bullivant and Ames (J. Cell Biol., 1966) indicate that the frozen cells are fractured in many different planes. This fracturing or cleaving along various planes allows one to gain a three dimensional relation of the cellular components as a result of such a manipulation. When replicas that are obtained by the freeze-fracture method are observed in the electron microscope, cross fractures of the cell wall and membranes that comprise the photosynthetic lamellae are apparent as demonstrated in Figures 1 & 2.A large portion of the Anabaena cell is composed of undulating layers of cytoplasm that are bounded by unit membranes that comprise the photosynthetic membranes. The adjoining layers of cytoplasm are closely apposed to each other to form the photosynthetic lamellae. Occassionally the adjacent layers of cytoplasm are separated by an interspace that may vary in widths of up to several 100 mu to form intralamellar vesicles.

Download Full-text