Intracellular infection of aposymbiotic Hydra viridis by a foreign free-living Chlorella sp.: initiation of a stable symbiosis

1984 ◽  
Vol 65 (1) ◽  
pp. 265-277
Author(s):  
M. Rahat ◽  
V. Reich
Keyword(s):  
Surrounding Medium ◽  
Reproduction Rate ◽  
Free Living ◽  
Intracellular Infection ◽  
Chlorella Sp ◽  
Dense Substance ◽  
Endodermal Cells ◽  
Hydra Viridis

An aposymbiotic strain of Hydra viridis became infected with free-living Chlorella sp. A stable symbiosis formed that differed in its characteristics from other known Chlorella/Hydra symbioses. The algae reproduced and formed clusters in host endodermal cells, inside large vacuoles filled with an electron-dense substance. A few algae were found to be digested by the hydra, but the apparently uncontrolled reproduction rate of the algae more than compensated for this loss. Surplus algae were expelled into the coelenteron and eventually into the surrounding medium. The expelled algae were repeatedly re-engulfed by the hydra during its feeding, forming a process of continuous reinfection. We suggest that such repeated reinfection of the hydra by the expelled algae provides the host with an endless number of Chlorella from which it might in time select a suitable adapted, controllable symbiont. The present newly formed symbiosis might serve as a model for the study of evolution of algal endosymbioses.

Algal endosymbiosis in brown hydra: host/symbiont specificity

1986 ◽  
Vol 86 (1) ◽  
pp. 273-286 ◽  
Author(s):  
M. Rahat ◽  
V. Reich
Keyword(s):  
Ecological Factors ◽  
Vacuolar Membrane ◽  
Physiological Strain ◽  
Free Living ◽  
Daughter Cells ◽  
Green Hydra ◽  
Endodermal Cells ◽  
Hydra Viridis ◽  
Algal Distribution

Host/symbiont specificity has been investigated in non-symbiotic and aposymbiotic brown and green hydra infected with various free-living and symbiotic species and strains of Chlorella and Chlorococcum. Morphology and ultrastructure of the symbioses obtained have been compared. Aposymbiotic Swiss Hydra viridis and Japanese H. magnipapillata served as controls. In two strains of H. attenuata stable hereditary symbioses were obtained with Chlorococcum isolated from H. magnipapillata. In one strain of H. vulgaris, in H. oligactis and in aposymbiotic H. viridis chlorococci persisted for more than a week. Eight species of free-living Chlorococcum, 10 symbiotic and 10 free-living strains of Chlorella disappeared from the brown hydra within 1–2 days. In H. magnipapillata there was a graded distribution of chlorococci along the polyps. In hypostomal cells there were greater than 30 algae/cell while in endodermal cells of the mid-section or peduncle less than 10 algae/cell were found. In H. attenuata the algal distribution was irregular, there were up to five chlorocci/cell, and up to 20 cells/hydra hosted algae. In the dark most cells of Chlorococcum disappeared from H. magnipapillata and aposymbiotic hydra were obtained. Chlorococcum is thus an obligate phototroph, and host-dependent heterotrophy is not required for the preservation of a symbiosis. The few chlorococci that survived in the dark seem to belong to a less-demanding physiological strain. In variance with known Chlorella/H. viridis endosymbioses the chlorococci in H. magnipapillata and H. attenuata were tightly enveloped in the vacuolar membrane of the hosting cells with no visible perialgal space. Chlorococcum reproduced in these vacuoles and up to eight daughter cells were found within the same vacuole. We suggest that the graded or scant distribution of chlorococci in the various brown hydra, their inability to live in H. viridis and the inability of the various chlorellae to live in brown hydra are the result of differences in nutrients available to the algae in the respective hosting cells. We conclude that host/symbiont specificity and the various forms of interrelations we show in green and brown hydra with chlorococci and chlorellae are based on nutritional-ecological factors. These interrelations demonstrate successive stages in the evolution of stable obligatoric symbioses from chance encounters of preadapted potential cosymbionts.

scholarly journals Correlations between characteristics of some free-living Chlorella sp. and their ability to form stable symbioses with Hydra viridis

1985 ◽  
Vol 74 (1) ◽  
pp. 257-266
Author(s):  
M. Rahat ◽  
V. Reich
Keyword(s):  
Growth Rate ◽  
Growth Rates ◽  
Normal Growth ◽  
Digestive Cell ◽  
Free Living ◽  
Chlorella Sp ◽  
Proteose Peptone ◽  
Different Strains ◽  
Hydra Viridis

Aposymbiotic polyps of Hydra viridis were infected with 17 strains of in vitro cultured Chlorella sp. Larvae of Artemia fed with the chlorellae were used as an infecting vector. Of the 17 strains, seven formed stable symbioses and one formed a transient infection that disappeared within several weeks. Chlorellae of the nine other strains were cleared out of the infected hydra within 2–3 days. There was a distinct correlation between the ability of the chlorellae to form stable symbioses and their ability to adapt and grow in media enriched with 0.5% proteose peptone. Only strains that grew in the latter medium formed symbioses with the hydra. The symbioses formed with the different strains of chlorellae differed from one another. Hydra infected with some strains greened completely while those infected with other strains greened only partially. The degree of infection varied also within each population, and there were differences in the distribution of the various chlorellae along the stalk and inside the digestive cells of the hydra. Growth rates of the infected hydra were all less that those of aposymbiotic hydra or of hydra hosting native zoochlorellae. We conclude that adaptability to a nutrient-rich environment inside the perialgal vacuole of the digestive cell and a sufficient growth rate therein are crucial to the ability of chlorellae to form stable symbioses with H. viridis. In time, co-adaptation of hydra and chlorellae would restore the normal growth rate of the former and bring about regularity to the form and extent of infection by the latter.

scholarly journals Further studies of the secretory pathway in thrombin-stimulated human platelets

Blood ◽  
1987 ◽  
Vol 69 (4) ◽  
pp. 1196-1203 ◽  
Author(s):  
JG White ◽  
M Krumwiede
Keyword(s):  
Tannic Acid ◽  
Secretory Pathway ◽  
Surrounding Medium ◽  
Human Platelets ◽  
Secretory Process ◽  
Intense Staining ◽  
Platelet Surface ◽  
Dense Deposits ◽  
Dense Substance ◽  
Secretory Products

Abstract The pathway followed by secretory products stored in platelet alpha granules during the release reaction remains controversial. Tannic acid has been used in the present study as an electron-dense stain to follow the secretory process in thrombin-stimulated platelets. Preliminary experiments demonstrated that tannic acid precipitates fibrinogen, and binds osmium tetroxide to fibrinogen and fibrin strands. Examination of platelets fixed at short intervals after exposure to thrombin and incubated in solutions containing tannic acid revealed electron-dense deposits of osmium not apparent in resting platelets. Granules and lumina of channels making up the open canalicular system (OCS) were unstained in discoid cells. However, exposure to thrombin at concentrations of 1 to 5 U/mL for thirty seconds or more resulted in intense staining of alpha granules by osmium. Some granules communicated directly with dilated channels of the OCS, and several were frequently connected to the same canaliculus. The electron-dense substance in swollen granules and channels appeared to be in the process of extrusion through narrow or dilated openings of the OCS onto the platelet surface. Granule-to-granule fusion and formation of sealed vacuoles of fused granule products unstained by tannic acid-osmium were not observed. The findings support the concept that secretion by stimulated human platelets results from development of direct communications between granules and channels of the OCS and subsequent extrusion of products through channel pores to the surrounding medium.

scholarly journals Further studies of the secretory pathway in thrombin-stimulated human platelets

Blood ◽  
1987 ◽  
Vol 69 (4) ◽  
pp. 1196-1203 ◽  
Author(s):  
JG White ◽  
M Krumwiede
Keyword(s):  
Tannic Acid ◽  
Secretory Pathway ◽  
Surrounding Medium ◽  
Human Platelets ◽  
Secretory Process ◽  
Intense Staining ◽  
Platelet Surface ◽  
Dense Deposits ◽  
Dense Substance ◽  
Secretory Products

The pathway followed by secretory products stored in platelet alpha granules during the release reaction remains controversial. Tannic acid has been used in the present study as an electron-dense stain to follow the secretory process in thrombin-stimulated platelets. Preliminary experiments demonstrated that tannic acid precipitates fibrinogen, and binds osmium tetroxide to fibrinogen and fibrin strands. Examination of platelets fixed at short intervals after exposure to thrombin and incubated in solutions containing tannic acid revealed electron-dense deposits of osmium not apparent in resting platelets. Granules and lumina of channels making up the open canalicular system (OCS) were unstained in discoid cells. However, exposure to thrombin at concentrations of 1 to 5 U/mL for thirty seconds or more resulted in intense staining of alpha granules by osmium. Some granules communicated directly with dilated channels of the OCS, and several were frequently connected to the same canaliculus. The electron-dense substance in swollen granules and channels appeared to be in the process of extrusion through narrow or dilated openings of the OCS onto the platelet surface. Granule-to-granule fusion and formation of sealed vacuoles of fused granule products unstained by tannic acid-osmium were not observed. The findings support the concept that secretion by stimulated human platelets results from development of direct communications between granules and channels of the OCS and subsequent extrusion of products through channel pores to the surrounding medium.

scholarly journals Cytochrome P450 monooxygenase analysis in free-living and symbiotic microalgae Coccomyxa sp. C-169 and Chlorella sp. NC64A

ALGAE ◽  
2015 ◽  
Vol 30 (3) ◽  
pp. 233-239 ◽  
Author(s):  
Ntsane Trevor Mthakathi ◽  
Ipeleng Kopano Rosinah Kgosiemang ◽  
Wanping Chen ◽  
Molikeng Eric Mohlatsane ◽  
Thebeyapelo Jacob Mojahi ◽  
...  
Keyword(s):  
Cytochrome P450 ◽  
Cytochrome P450 Monooxygenase ◽  
Free Living ◽  
P450 Monooxygenase ◽  
Chlorella Sp ◽  
Symbiotic Microalgae

Ultrastructural Changes of the Symbiotic Chlorella-Like Alga Isolated from Hydra Viridis

1982 ◽  
Vol 40 ◽  
pp. 320-321
Author(s):  
K.W. Lee ◽  
R.H. Meints ◽  
D. Kuczmarski ◽  
J.L. Van Etten
Keyword(s):  
Time Course ◽  
Reciprocal Cross ◽  
Ultrastructural Level ◽  
Ultrastructural Changes ◽  
Symbiotic Relationship ◽  
Cell Recognition ◽  
Green Hydra ◽  
Different Strains ◽  
Hydra Viridis

The physiological, biochemical, and ultrastructural aspects of the symbiotic relationship between the Chlorella-like algae and the hydra have been intensively investigated. Reciprocal cross-transfer of the Chlorellalike algae between different strains of green hydra provide a system for the study of cell recognition. However, our attempts to culture the algae free of the host hydra of the Florida strain, Hydra viridis, have been consistently unsuccessful. We were, therefore, prompted to examine the isolated algae at the ultrastructural level on a time course.

The Fine Structure of Rat Granulosa Cell Cultures Correlated with Progestin Secretion

1973 ◽  
Vol 31 ◽  
pp. 552-553
Author(s):  
T. M. Crisp ◽  
F.R. Denys
Keyword(s):  
Fine Structure ◽  
Granulosa Cell ◽  
Cell Cultures ◽  
Single Injection ◽  
Surrounding Medium ◽  
Petri Dish ◽  
Female Rats ◽  
Vaginal Smear ◽  
Immature Female ◽  
Serum Gonadotropin

The purpose of this paper is to present observations on the fine structure of rat granulosa cell cultures grown in the presence of an adenohypophyseal explant and to correlate the morphology of these cells with progestin secretion. Twenty-six day old immature female rats were given a single injection of 5 IU pregnant mares serum gonadotropin (PMS) in order to obtain ovaries with large vesicular follicles. At 66 hrs. post-PMS administration (estrus indicated by vaginal smear cytology), the ovaries were removed and placed in a petri dish containing medium 199 and 100 U penicillin/streptomycin (P/S)/ml. Under a 20X magnification dissecting microscope, some 5-8 vesicular follicles/ovary were punctured and the granulosa cells were expressed into the surrounding medium. The cells were transferred to centrifuge tubes and spun down at 1000 rpm for 5 mins.

Ultrastructure of neuromuscular relationships in the canine heartworm (dirofilaria immitis)

1986 ◽  
Vol 44 ◽  
pp. 278-279
Author(s):  
W. L. Steffens ◽  
Nancy B. Roberts ◽  
J. M. Bowen
Keyword(s):  
Dirofilaria Immitis ◽  
Domestic Dogs ◽  
Structural Description ◽  
Pharmacological Effects ◽  
Free Living ◽  
Canine Heartworm ◽  
The World ◽  
Synaptic Region ◽  
Muscle Innervation ◽  
Insight Into

The canine heartworm is a common and serious nematode parasite of domestic dogs in many parts of the world. Although nematode neuroanatomy is fairly well documented, the emphasis has been on sensory anatomy and primarily in free-living soil species and ascarids. Lee and Miller reported on the muscular anatomy in the heartworm, but provided little insight into the peripheral nervous system or myoneural relationships. The classical fine-structural description of nematode muscle innervation is Rosenbluth's earlier work in Ascaris. Since the pharmacological effects of some nematacides currently being developed are neuromuscular in nature, a better understanding of heartworm myoneural anatomy, particularly in reference to the synaptic region is warranted.

Ultrastructural Changes in the Root Meristem Cells of Rubus Chamaemorus L. (Cloudberry)

1975 ◽  
Vol 33 ◽  
pp. 562-563
Author(s):  
Arya K. Bal
Keyword(s):  
Root Meristem ◽  
Uranyl Acetate ◽  
Particulate Material ◽  
Ultrastructural Changes ◽  
Cell Organelles ◽  
Cytoplasmic Matrix ◽  
Golgi Membranes ◽  
Rubus Chamaemorus ◽  
Dense Substance ◽  
Ultrathin Sections

In the course of studies in the root meristem tissue of Rubus chamaemorus L. some important changes in the ultrastructural morphology were observed during the initiation of senescence at the end of the growing season.Root meristems were collected from naturally growing healthy populations of Cloudberry plants, and fixed in Karnovsky's mixture or in 2.5% glutaraldehyde in phosphate buffer. The samples were osmicated, dehydrated following usual methods and embedded in Epon. Ultrathin sections were stained in uranyl acetate and lead citrate.Figure 1 shows part of a dense cell in the meristem. The electron density of these cells is due to large amounts of a particulate material in the cytoplasmic matrix. The smallest particle seen in electron micrographs is about 40 A, although larger aggregates are also found, which remain randomly distributed in association with various cell organelles. Dense substance has been found associated with golgi membranes, proplastids, vacuoles and microtubules (Fig. 2).

Lead and lead toxicity in domestic and free living birds

2003 ◽  
Vol 32 (1) ◽  
pp. 3-13 ◽  
Author(s):  
N. De Francisco ◽  
N. De Francisco ◽  
N. De Francisco
Keyword(s):  
Lead Toxicity ◽  
Free Living
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