Differential rubisco content and photosynthetic efficiency of rol gene integrated Vinca minor transgenic plant: Correlating factors associated with morpho-anatomical changes, gene expression and alkaloid productivity.

Transgenic plants obtained from a hairy root line (PVG) of Vinca minor were characterized in relation to terpenoid indole alkaloids (TIAs) pathway gene expression and vincamine production. The hairy roots formed callus with green nodular protuberances when transferred onto agar-gelled MS medium containing 3.0mg/l zeatin. These meristematic zones developed into shoot buds on medium with 1.0mg/l 2, 4-dichlorophenoxyacetic acid and 40mg/l ascorbic acid. These shoot buds subsequently formed rooted plants when shifted onto a hormone-free MS medium with 6% sucrose. Transgenic nature of the plants was confirmed by the presence of rol genes of the Ri plasmid in them. The transgenic plants (TP) had elongated internodes and a highly proliferating root system. During glass house cultivation TP consistently exhibited slower growth rate, low chlorophyll content (1.02±0.08mg/gm fr. wt.), reduced carbon exchange rate (2.67±0.16µmolm-2s-1), less transpiration rate (2.30±0.20mmolm-2 s-1) and poor stomatal conductance (2.21±0.04mmolm-2 s-1) when compared with non-transgenic population. The activity of rubisco enzyme in the leaves of TP was nearly two folds less in comparison to non-transgenic controls (1.80milliunitsml-1mgprotein-1 against 3.61milliunits ml-1mgprotein-1, respectively). Anatomically, the TP had a distinct tetarch arrangement of vascular bundles in their stem and roots against a typical ployarched pattern in the non-transgenic plants. Significantly, the transgenic plants accumulated 35% higher amount of total TIAs (3.10±0.21% dry wt.) along with a 0.03% dry wt. content of its vasodilatory and nootropic alkaloid vincamine in their leaves. Higher productivity of alkaloids in TP was corroborated with more than four (RQ=4.60±0.30) and five (RQ=5.20±0.70) times over-expression of TIAs pathway genes tryptophan decarboxylase (TDC) and strictosidine synthase (STR) that are responsible for pushing the metabolic flux towards TIAs synthesis in this medicinal herb.

Effects of microplastics on European flat oysters, Ostrea edulis and their associated benthic communities.

Plastic pollution is recognised as an emerging threat to aquatic ecosystems, with microplastics now the most abundant type of marine debris. Health effects caused by microplastics have been demonstrated at the species level, but impacts on ecological communities remain unknown. In this study, impacts of microplastics on the health and biological functioning of European flat oysters (Ostrea edulis) and on the structure of associated macrofaunal assemblages were assessed in an outdoor mesocosm experiment using intact sediment cores. Biodegradable and conventional microplastics were added at low (0.8 µg L(-1)) and high (80 µg L(-1)) doses in the water column repeatedly for 60 days. Effects on the oysters were minimal, but benthic assemblage structures differed and species richness and the total number of organisms were ∼1.2 and 1.5 times greater in control mesocosms than in those exposed to high doses of microplastics. Notably, abundances of juvenile Littorina sp. (periwinkles) and Idotea balthica (an isopod) were ∼2 and 8 times greater in controls than in mesocosms with the high dose of either type of microplastic. In addition, the biomass of Scrobicularia plana (peppery furrow shell clam) was ∼1.5 times greater in controls than in mesocosms with the high dose of microplastics. This work indicates that repeated exposure to high concentrations of microplastics could alter assemblages in an important marine habitat by reducing the abundance of benthic fauna.

From herkogamy to cleistogamy--development of cleistogamy in periwinkle.

Periwinkle (Catharanthus roseus [L.] G. Don), an important medicinal plant, is an allogamous species in which the stigma is below the anthers. The receptive portion is at the base of the stigmatic head and thus automatic intra-flower self-pollination is excluded. The structure of the flower is of typical reverse herkogamy and pollination occurs through nectar-seeking insects. A few self-pollinating strains are also reported in which self-pollination is brought about by an increase in length of the style or of the ovary. Self-pollination is governed by allelic duplicate genes recessive to allogamy. An induced monogenic recessive mutant (EMS 17-1) with caducous closed corolla (corolla abscising before anthesis), isolated from variety, Dhawal, was crossed with two self-pollinating strains to study the possibility of obtaining cleistogamous recombinants combining closed corolla and self-pollination traits. Cleistogamous plants were obtained in which development of fruits and seeds occurred without opening of the corolla. Closed corolla and self-pollination were found to be independently inherited. A dominant gene in the parent in which self-pollination occurred due to an increase in length of the ovary, appeared to completely or partially inhibit expression of the gene for closed corolla in homozygous or heterozygous condition, respectively. The genetic basis of development of cleistogamy is described. Cleistogamy in periwinkle would facilitate in ensuring genetic purity, pollen containment, and seed production even in the absence of pollinators. This appears to be the first report on the development of cleistogamous plants in an allogamous species.

Fiddler crabs facilitate Spartina alterniflora growth, mitigating periwinkle overgrazing of marsh habitat.

Ecologists have long been interested in identifying and testing factors that drive top-down or bottom-up regulation of communities. Most studies have focused on factors that directly exert top-down (e.g., grazing) or bottom-up (e.g., nutrient availability) control on primary production. For example, recent studies in salt marshes have demonstrated that fronts of Littoraria irrorata periwinkles can overgraze Spartina alterniflora and convert marsh to mudflat. The importance of indirect, bottom-up effects, particularly facilitation, in enhancing primary production has also recently been explored. Previous field studies separately revealed that fiddler crabs, which burrow to depths of more than 30 cm, can oxygenate marsh sediments and redistribute nutrients, thereby relieving the stress of anoxia and enhancing S. alterniflora growth. However, to our knowledge, no studies to date have explored how nontrophic facilitators can mediate top-down effects (i.e., grazing) on primary-producer biomass. We conducted a field study testing whether fiddler crabs can facilitate S. alterniflora growth sufficiently to mitigate overgrazing by periwinkles and thus sustain S. alterniflora marsh. As inferred from contrasts to experimental plots lacking periwinkles and fiddler crabs, periwinkles alone exerted top-down control of total aboveground biomass and net growth of S. alterniflora. When fiddler crabs were included, they counteracted the effects of periwinkles on net S. alterniflora growth. Sediment oxygen levels were greater and S. alterniflora belowground biomass was lower where fiddler crabs were present, implying that fiddler crab burrowing enhanced S. alterniflora growth. Consequently, in the stressful interior S. alterniflora marsh, where subsurface soil anoxia is widespread, fiddler crab facilitation can mitigate top-down control by periwinkles and can limit and possibly prevent loss of biogenically structured marsh habitat and its ecosystem services.

[Tissue culture of Vinca minor and determination of vincamine].

OBJECTIVE: To study tissue culture of Vinca minor and determine the content of vincamine. METHOD: Leaf blades, stalks, root segment of V. minor were used as explants to study the effect of 2, 4-D,6-BA,NAA on its callus induction and vincamine contents in the orthogonal design experiment. In the peak period of callus formation, vincamine content in callus of V. minor and sterile plants was determined by HPLC. The experimental data was statistically analyzed. RESULT: The content of 6-BA and NAA had no significant effect on its callus induction. But the content of 2, 4-D had significant effect on its callus induction. Within 20,40,60 d, the content of vincamine in sterile plant was (0.015 +/- 0.003)%, (0.097 +/- 0.001)% , (0.113 +/- 0.06)%, respectively. In the peak period of callus formation, vincamine content in callus of leaf blades, stalks, root segment was (0.024 +/- 0.0025)%, (0.016 +/- 0.0015)%, (0.010 +/- 0.0015)%, respectively. To 30 days of subculture, vincamine content in callus of leaf blades, stalks, root segment was (0.041 +/- 0.002)%, (0.019 +/- 0001)%, (0.016 +/- 0.002)%, respectively. CONCLUSION: The optimal hormone combination for callus initiation was MS +2, 4-D 1.0 mg x L(-1) +6-BA 0.5 mg x L(-1) + NAA 0.5 mg x L(-1). In different growth periods, vincamine content in sterile plants is significantly different. From different explants in callus vincamine content is different, in which leaves callus is significantly higher than that of stems, roots produced callus organization.

Elevated female fecundity as a possible compensatory mechanism in response to trematode infestation in populations of Littorina saxatilis (Olivi).

Co-evolution between parasites and their hosts may lead to changes in the life-history traits of the host that promote sustainability of their populations despite parasite pressure. Such changes are expected to be especially pronounced in the host-parasite systems where parasites cause complete castration of their hosts. We have studied populations of the rough periwinkle, Littorina saxatilis, infested by castrating trematode species, in order to determine whether high infestation levels are associated with a compensatory increase in host fecundity. To test this hypothesis, we determined female fecundity in populations with trematode prevalence spanning from <1% to 30-75%, and followed long-term changes in female fecundity and trematode infestation in two heavily infested populations of L. saxatilis. The broad-scale geographic analysis of populations with different trematode burdens showed that fecundity of uninfected females is significantly higher in highly infested L. saxatilis populations than in those with low trematode burdens. This is also supported by a comparison of fecundity in two pairs of geographically adjacent populations with contrasting trematode levels, revealing higher fecundity of uninfected females in heavily infested populations. Higher fecundity could be explained by the larger size of uninfected females in some heavily infested populations but not in others. Long-term (15-20 years) intra-population analysis performed in two heavily infested L. saxatilis populations showed that female fecundity increased in parallel with a long-term increase in trematode prevalence from 20% to >75% in one population, but remained high and relatively stable in the second population, reflecting its consistently high trematode prevalence (40-65%). These data support the hypothesis that an increase in female fecundity may be a population compensation mechanism in response to heavy trematode infestation in L. saxatilis and suggest the possible involvement of both natural selection and fast (physiological) regulation mechanisms.

An experimental study of the effects of weed invasion on lizard phenotypes.

We examined how a weed affected the basking and activity of a diurnal lizard, and the potential cascading effects of these shifts for life history strategies and expression of morphology. Hatchlings of the diurnal lizard Lampropholis delicata were raised to maturity in outdoor enclosures that mimicked high, moderate and low invasion by a sprawling plant (blue periwinkle, Vinca major). Skinks depend on sunlight for growth and maintenance. Periwinkle differs from displaced grassland by being structurally complex and blocking sunlight. Lizards restricted to the enclosure floor achieved preferred body temperatures only when exposure to periwinkle was moderate or low. However, lizards in high invasion enclosures could reach preferred body temperatures by climbing plants and basking on exposed canopy. This shift in basking strategy resulted in lizards growing longer hind limbs compared with animals that rarely (moderate invasion) and never (low invasion) climbed plants. Consequently, lizards reared in high invasion enclosures sprinted faster than conspecifics reared in lower invasion environments. Throughout the study there was no significant variation among treatments in the tendency of animals to be moving when they were not hidden. However, lizards in high invasion treatments hid more often during the day, were lighter in body mass, and females had lighter clutch masses and offspring than did those from moderate and low invasion enclosures. Thus, microhabitat degradation can drive a cascade of changes to an animal's ecology.

Acholeplasma laidlawii PG8 culture adapted to unfavorable growth conditions shows an expressed phytopathogenicity.

Mycoplasmas are the smallest, self-replicating, prokaryotic organisms with avid biochemical potential and spreading in higher eukaryotes in nature. In this study, Acholeplasma laidlawii PG8 cells were cultivated on a deficient medium for 480 days resulting in a mycoplasma culture that was adapted in vitro to unfavorable growth conditions. Cells that survive this condition had decreased sizes (about 0.2 microm) and increased phytopathogenicity. This resulted in more frequent appearance of various morphological alterations when plants of vinca (Vinca minor L.) were infected by adapted mycoplasma cells. The increasing pathogenicity was accompanied by changes in genome expression in these adapted cells. Further studies are needed to explore the exact mechanisms that permit adaptation to unfavorable growth conditions and changes in phytopathogenic potential.