METABOLIC RELATIONSHIPS BETWEEN GREEN HYDRA AND ITS SYMBIOTIC ALGAE

Freshly isolated ‘European’ algae phagocytosed by digestive cells of ‘European’ green hydra were distinguished from the pre-existing population of algae by prestaining with the fluorescent agent Calcofluor White. Only a small number of phagocytosed ‘European’ algae or algae cultured from Paramecium bursaria avoided lysosomal degradation and were transported to the cell base in symbiotic digestive cells, although in aposymbionts up to 50% of phagocytosed algae were transported. Degradation of almost all phagocytosed algae also occurred in digestive cells of hydra containing only half the normal complement of algae, and in those of hydra symbiotic with algae cultured from Paramecium . The presence of algae at the bases of digestive cells appears to negate the mechanism by which potentially symbiotic algae normally avoid lysosomal attack. This protects the host cell and its symbionts from invasion by ‘foreign’ algae and suggests that once established the green hydra symbiosis is conservative in nature.

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The green hydra symbiosis. IV. Entry of symbionts into digestive cells

Proceedings of the Royal Society of London Series B Biological Sciences ◽

10.1098/rspb.1982.0057 ◽

1982 ◽

Vol 216 (1202) ◽

pp. 1-6 ◽

Cited By ~ 12

Keyword(s):

Electron Microscopy ◽

Scanning Electron Microscopy ◽

Plasma Membrane ◽

Digestive Cell ◽

Particle Type ◽

Digestive Cells ◽

Symbiotic Algae ◽

Green Hydra ◽

Different Types ◽

Scanning Electron

Scanning electron microscopy showed that particles, including symbiotic algae, non-symbiotic algae and latex spheres, entered digestive cells of European green hydra by two different types of phagocytosis: (i) they sank into crater-like formations of the digestive-cell surface; or (ii) they were enveloped by raised, funnel-like extensions of plasma membrane. The morphology selected did not depend on particle type: there was no evidence for specific recognition of symbiotic algae during phagocytosis.

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Expulsion of Symbiotic Algae during Feeding by the Green Hydra – a Mechanism for Regulating Symbiont Density?

PLoS ONE ◽

10.1371/journal.pone.0002603 ◽

2008 ◽

Vol 3 (7) ◽

pp. e2603 ◽

Cited By ~ 14

Author(s):

Yelena Fishman ◽

Eliahu Zlotkin ◽

Daniel Sher

Keyword(s):

Symbiotic Algae ◽

Green Hydra

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Temporal relationships of host cell and algal mitosis in the green hydra symbiosis

Journal of Cell Science ◽

10.1242/jcs.58.1.423 ◽

1982 ◽

Vol 58 (1) ◽

pp. 423-431

Author(s):

P.J. McAuley

Keyword(s):

Cell Division ◽

Host Cell ◽

Digestive Cell ◽

Digestive Cells ◽

Symbiotic Algae ◽

Green Hydra ◽

Temporal Relationships ◽

Dividing Cells ◽

Cell Mitosis ◽

Mitotic Cells

In fed hydra or excised regenerating peduncles there are increases in the mitotic indices of both digestive cells and the symbiotic algae that reside within them. Conversely, algal and digestive cell mitotic indices decrease in starved hydra. The temporal relationships of algal and host cell division differ in fed hydra and regenerating peduncles. After feeding, algal and digestive cell mitotic indices both reach a peak at about the same time; during regeneration, first the algae and then the digestive cells divide. Thus, mitotic digestive cells in regenerating peduncles contain more algae than those in gastric regions of fed hydra. However, in both cases mitotic digestive cells contain more algae than non-mitotic cells. The algae appear to be partitioned at random between daughter digestive cells at teleophase. It is suggested that the division of the symbiotic algae is closely related to that of the digestive cells in which they maintained. Mitosis of algae is stimulated by host cell mitosis, but in non-dividing cells algal mitosis is restricted. Possible mechanisms by which the host digestive cells could restrict algal division are discussed.

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The cell cycle of symbiotic Chlorella. IV. DNA content of algae slowly increases during host starvation of green hydra

Journal of Cell Science ◽

10.1242/jcs.85.1.73 ◽

1986 ◽

Vol 85 (1) ◽

pp. 73-84

Author(s):

P.J. McAuley ◽

L. Muscatine

Keyword(s):

Cell Size ◽

Dna Content ◽

Algal Cell ◽

S Phase ◽

Symbiotic Algae ◽

Daughter Cells ◽

Green Hydra ◽

Significant Difference ◽

Preceding Period ◽

Chlorella Algae

The distribution of DNA content of symbiotic Chlorella algae freshly isolated from green hydra was compared with that of cultured Chlorella of the NC64A strain, using flow cytometry. In nonlogarithmic cultures of NC64A most cells had accumulated in G1 phase, while in logarithmic cultures a peak containing cells in S phase and mitosis could be distinguished from the larger G1 peak. However, symbiotic algae showed a single broad peak in which there was no clear distinction between G1 and S phase/mitosis. When hydra were starved for a prolonged period, inhibiting host cell and algal division, the DNA content of the symbiotic algae slowly increased, and the number of daughter cells produced after a single feeding increased with the length of the preceding period of starvation. This suggests that symbiotic algae are able to cycle slowly through S phase, but unless the host is fed they cannot traverse into mitosis and complete the cell division cycle. No significant difference in cell size was found between algae producing either four or eight daughter cells after 1-day- or 22-day-starved hydra were fed, suggesting that algal cell size did not determine the number of daughter cells produced. Instead, this may be dependent upon the length of time the cell had spent in S phase prior to receiving the, as yet unknown, stimulus to enter into mitosis.

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

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100054212 ◽

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.

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New Observations on Green Hydra Symbiosis

Folia Biologica ◽

10.3409/173491607780006380 ◽

2007 ◽

Vol 55 (1) ◽

pp. 77-79 ◽

Cited By ~ 2

Author(s):

Goran Kovačević ◽

Mirjana Kalafatić ◽

Nikola Ljubešić

Keyword(s):

Green Hydra

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Transfer of photosynthate in green hydra

Endosymbiosis and cell biology ◽

10.1515/9783111385068-027 ◽

1980 ◽

pp. 259-268

Keyword(s):

Green Hydra

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Photoinduced toxicity of fluoranthene on primary processes of photosynthesis in lichens

The Lichenologist ◽

10.1017/s0024282907006111 ◽

2006 ◽

Vol 39 (1) ◽

pp. 91-100 ◽

Cited By ~ 11

Author(s):

Marie KUMMEROVÁ ◽

štěpán ZEZULKA ◽

Jana KRULOVÁ ◽

Jan TŘÍSKA

Keyword(s):

Chlorophyll Fluorescence ◽

Bioconcentration Factor ◽

Lichen Species ◽

Chlorophyll Fluorescence Parameters ◽

Fluorescence Parameters ◽

Photochemical Processes ◽

Symbiotic Algae ◽

Lasallia Pustulata ◽

Photoinduced Toxicity ◽

Umbilicaria Hirsuta

The effect of increasing concentrations (0·01, 0·1, 1 and 5 mg l−1) of intact (FLT) and photo-modified (phFLT) fluoranthene and the duration of exposure (1, 2, 3, 5 and 7 days) on the chlorophyll fluorescence parameters (F0, FV/FM, and ΦII) of symbiotic algae in the thalli of two foliose lichens Lasallia pustulata and Umbilicaria hirsuta was investigated. In addition the FLT concentration in thalli of both lichen species was determined and a bioconcentration factor (BCF) was calculated. The results obtained demonstrated that the concentrations of FLT and especially phFLT (1 and 5 mg l−1) applied affected primary photochemical processes of photosynthesis in the algae of both lichen species. The F0 value increased and the FV/FM and ΦII values decreased. The fluoranthene content in the thallus of both lichen species increased with increasing FLT concentration in the environment.

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