Hydra viridissima(green Hydra) rapidly recovers from multiple magnesium pulse exposures

2015 ◽  
Vol 34 (8) ◽  
pp. 1734-1743 ◽  
Author(s):  
Andrea E. Prouse ◽  
Alicia C. Hogan ◽  
Andrew J. Harford ◽  
Rick A. van Dam ◽  
Dayanthi Nugegoda
Keyword(s):  
Green Hydra

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.

New Observations on Green Hydra Symbiosis

2007 ◽  
Vol 55 (1) ◽  
pp. 77-79 ◽  
Author(s):  
Goran Kovačević ◽  
Mirjana Kalafatić ◽  
Nikola Ljubešić
Keyword(s):  
Green Hydra

Stress tolerance alteration in the freshwater cnidarian green hydra (Hydra viridissima) via symbiotic algae mutagenesis

Symbiosis ◽  
2020 ◽  
Vol 82 (3) ◽  
pp. 189-199
Author(s):  
Siao Ye ◽  
Meenakshi Bhattacharjee ◽  
Evan Siemann
Keyword(s):  
Stress Tolerance ◽  
Symbiotic Algae ◽  
Green Hydra

Transfer of photosynthate in green hydra

1980 ◽  
pp. 259-268
Keyword(s):  
Green Hydra

Insights into Symbiotic Acquisition of Organelles from Studies of the Green Hydra

1992 ◽  
pp. 45-52
Author(s):  
R. L. Pardy ◽  
C. L. Royce
Keyword(s):  
Green Hydra

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.

Regulation of intracellular algae by various strains of the symbiotic Hydra viridissima

1986 ◽  
Vol 85 (1) ◽  
pp. 187-195
Author(s):  
P. Bossert ◽  
K.W. Dunn
Keyword(s):  
Host Cell ◽  
Mitotic Index ◽  
Large Strain ◽  
Green Hydra

In observations on three strains of green hydra, the host and the algal mitotic index is closely coordinated only for the smallest. As the hydra strain size increases the coordination of host and algal mitosis progressively breaks down, first in timing for a medium-sized strain and then in rate for a large strain. Despite disparities between host and algal mitotic index, the number of algae per host cell remains constant in all strains during the interval measured. To account for this constancy we suggest that the hydra may either prolong the duration of the algal tetraspore stage or cull excess algae.

Interference of asexual and sexual reproduction in the green hydra

2010 ◽  
Vol 26 (1) ◽  
pp. 147-152 ◽  
Author(s):  
Anita Kaliszewicz
Keyword(s):  
Sexual Reproduction ◽  
Green Hydra

Partitioning of symbiotic Chlorella at host cell telophase in the green hydra symbiosis

1990 ◽  
Vol 329 (1252) ◽  
pp. 47-53 ◽  
Keyword(s):  
Cell Division ◽  
Host Cell ◽  
Daughter Cell ◽  
Control Cell ◽  
Culture Conditions ◽  
Digestive Cells ◽  
Density Dependent ◽  
Green Hydra ◽  
The Mean ◽  
Control Cell Division

Although there is much evidence that green hydra digestive cells control cell division of their Chlorella symbionts, so that the symbionts divide only at host cell division, it is not clear how the population size of symbionts (numbers per cell) is regulated. In constant culture conditions the mean number of symbionts per cell also remains constant, but with a very large variance about the mean. The way in which symbionts are partitioned at host cell division appears to account for that variation. By counting numbers of Chlorella in daughter cells at late telophase it was found that partitioning of Chlorella symbionts was not symmetrical, but at random, closely following that predicted by the binomial distribution if it is assumed that each symbiont had an equal probability of entering either host daughter cell. A better fit to the predicted distribution was obtained from observations of partition in digestive cells from excised regenerating peduncles than in those from recently fed gastric regions, possibly because in the former, algae have completed their division before the host cell divides, while in the latter algal and host cell division takes place at the same time. There was only a small effect of differences in daughter cell volume on numbers of symbionts received, but comparison of variance and coefficient of variation of numbers of algae in mother (post-algal division, pre-partition) and daughter telophase digestive cells (pre-division, post-partition) suggested that algal division at host mitosis was density dependent. Random partitioning of algae at host cell telophase would account for the wide variation in numbers of algae per cell, and compensatory density-dependent algal division at the next host cell mitosis would ensure stability of the mean algal population.

The green hydra symbiosis. VII. Conservation of the host cell habitat by the symbiotic algae

1982 ◽  
Vol 216 (1205) ◽  
pp. 415-426 ◽  
Keyword(s):  
Host Cell ◽  
Lysosomal Degradation ◽  
Normal Complement ◽  
Calcofluor White ◽  
Digestive Cells ◽  
Symbiotic Algae ◽  
Green Hydra ◽  
Fluorescent Agent ◽  
Almost All ◽  
Cell Base

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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