Chick embryos (Gallus domesticus) exposed continuously from day one until 18 days of incubation to a 2G acceleration (hyperG chicks) force hatched with altered macular epithelia. Fertile eggs were placed in an incubator and exposed to 2G on a centrifuge by the original apparatus until 18 days of incubation. Effective 2G loads were obtained by rotating the apparatus at a constant velocity of 327.5 degree/sec with the incubator mounted at 55 cm from the center axis [1]. The vestibules of the newly hatch chicks were dissected and fixed in 2.5% glutaraldehyde. The utricles were rinsed in phosphate buffer, postfixed with 2% osmic acid and dehydrated in graded ethanol and embedded in plastic. Semithin sections were examined under Light microscopy with computerized video imaging system [2] and ultrathin sections were examined under TEM.

Chronic streptomycin (STP) administration to young rats for 49 consecutive days intramuscularly affected the rats equilibrium, and balance. Behavioral measures indicated motor-related impairment and rats inability to swim correctly or upright themselves when dunk in a water tank. Moreover, the affected rats failed to walk straight on a inclined platform. Upon termination of the STP administration, motor-related functions returned to pre-administration levels in some animals (recovered group), but not in others (un-recovered group) suggesting that organs involved in maintenance of equilibrium and balance of the body were affected, but later recuperated. The inner ear of both groups and sham controls were processed for histology and transmission electron microscopy and examined.

Twenty day old male Long Evans rats were injected daily in alternating hindlimbs with 400mg/Kg body weight STP. Control rats were injected physiological saline, up to 57 days when they began the recovery period of 8-12 weeks without further injections.

We have been investigating the development of the toe-pads of the frog Phyllomedusa irinhuiis. Several families of frog appear to have evolved rather similar digits with expanded terminal pads where ventral surfaces are specialised for adhesion. Although toe-pad structure has been extensively studied, development - which may gives clues to evolution - has not.

Adult and eggs of P. Iriniialis were collected from Trinidad, West Indies. Tadpoles were grown in our aquarium in Glasgow. We fixed front and hind digits of tadpoles at Gosner (1960) stages 37-42, froglets at stage 43-46, and adults. Pads were then processed for SEM.

Adult toe pads have a specialised epidermis with a surface layer of hexagonallyshaped cells, separated by deep clefts into which mucus glands open. Each pad is separated from the rest of the digit by a circumferal groove (Fig. 1).

Ruppia maritima L. is a submerged halophyte which occurs frequently in estuaries where sodium chloride is the dominant salt. Unlike terrestrial halophytes, R. maritima does not possess any specialised salt-secreting structures such as salt glands. Knowledge of salt tolerance mechanisms in this plant is important to our understanding of its biology. In a previous study it was shown that leaf epidermal cells of R. maritima, which possess transfer cell characteristics, are implicated in salt regulation. In the present investigation, the effect of calcium (Ca) on salt tolerance of leaf epidermal cells was studied since Ca has been found to be an important factor in resistance to salt stress in terrestrial plants.

Plants were grown in artificial seawater of high salinity (33%) and at two different Ca concentrations : 400 ppm (high Ca) and 100 ppm (low Ca).

Trace metals, such as manganese (Mn) and aluminum (Al), show increased solubility as soil acidity increases. Uptake of these elements may approach toxic concentrations in some plant species growing in acid forest soils. Previously, we had excellent results when chromium trioxide (CrO3) was used as the freeze substitution fixative in examining Al-treated plant and fungal tissue.1-2 However, when the fixative was used to study Mn toxicity, peak overlap (CrK β and MnKα) made it difficult to determine the location of Mn. In contrast, osmium tetroxide (OsO4) has no overlapping peak with Mn and is an excellent freeze substitution fixative. This study compares the use of OsO4 and CrO3 as fixatives for energy dispersive x-ray microanalysis (EDS) of the effect of Mn on ultrastructure and element localization in sugar maple leaves.

Viruses grouped in the family Potyviridaeare long flexious rod-shaped viruses and cause the most damage of all plant vims groups. They possess a single stranded positive sense RNA genome that encodes a single polyprotein product which yields eight or more proteins by secondary processing. Considerable efforts have been made to transform plants with DNA or RNA sequences of these proteins in hopes of obtaining pathogen-derived resistant plants. Hull has suggested that a close assessment of the risks involved in field release of transformed plants would be desirable. However, to our knowledge, there have been no published reports regarding properties of viruses that do infect some transformed plants. We describe here an ultrastructural appearance of transgenic plant cells infected by potato virus Y (PVY) (ATCC PV No. 50; PVY-50) and unusual mitochondrial aggregation with the virus.

In flowering plants, pollination and the process of fertilization are complex processes involving a series of cell-to-cell communication events. Though details of the progression of the pollen tube through the pistil, beginning with germination of the pollen grain on the stigma and culminating with delivery of the sperm cells to the embryo sac, are well established for several higher plant species, the mechanisms involved have yet to be elucidated. It has been shown that the transmitting tissue, which coincides with the path of pollen tubes in the gynoecium, is composed of highly secretory cells characterized by an extensive extracellular matrix (ECM). The actual roles that this ECM plays in pollination are currently unknown, although functions proposed include mechanical and/or chemotropic pollen tube guidance as well as pollen tube nutrition.

Most endosymbionts remain separated from their host cell by a derivative of the phagocytic membrane. This membrane and its contents have been defined as a novel “organelle-like” structure called a symbiosome. However, in the case of many cnidarian-dinoflagellate symbioses the putative symbiosome is composed of multiple layers of apparent membranes (Fig. 1). In the past the origin of these membranes has been assigned to host and/or symbiont with very little experimental evidence to support either view; however, several interesting hypotheses have been proposed to explain the origin of the “membranes”. Trench and Blank suggest that occasionally the outer most layer of the vegetative symbiont's cell wall is sloughed off the surface of the cell. They concede that the outer most layer of “membranes” must be the host vacuolar membrane, but believe that it simply prevents the sloughed layer from moving away from the cell, (as would happen in culture), and that, over time, multiple sloughed layers accumulate beneath the host vacular membrane.

Phloem proteins are specifically presented in phloem tissues of monocotyledons and dicotyledons. Ultrastructural studies showed that they were filamentous, spherical, tubular, crystalline and amorphous in shaped They were present in the sieve elements and sometimes are also found in companion cells and phloem parenchyma cells. The diversities in shape and biogenesis of plant p-protein in relation to plant species and developmental stage of phloem tissues were reported. In the present study, a 42.5 kDA protein obtained from phloem exudate of Luffa cylindrica fruits were examined with amino acid composition, immnoblotting, and immunolocalization.

Phloem exudates leaking from Luffa cylindrica fruits by a simple razor blade cutting were mixed with the extraction medium containing antioxidant and rapidly separated by 2-dimensional gel of native and sodium dodecylsulfate (SDS) polyacrylamide gel electrophoresis (PAGE).