Leaf production,reproductive patterns,field germination and seedling survival in Chamaedorea bartlingiana,a dioecious understory palm

Summary Chamaedorea bartlingiana is a dioecious palm that grows in the cloud forest understories of the Venezuelan Andes. Age and sexual differences in phenology and reproductive patterns were studied in labelled individuals of all age categories. This species has long-lived leaves and low leaf production, both characteristic of understory plants. Growth rates are lower in juveniles than in adults and in females than in males, as in other palms. Male and female individuals show different reproductive patterns. Male inflorescences are always produced at the same rate and the probability of surviving until anthesis is constant. Females produce reproductive buds at the same rate as males, but these buds have a 35% probability of becoming a ripe infrutescence if the plant has infrutescences already growing, and 70% if it does not. This pattern and the slow growth of inflorescences (1 year for males from bud to flowers, 2 years for females from bud to ripe fruits) cause a pluriannual reproductive pattern at the population level. Field germination does not follow this pattern, but shows one annual peak probably related to environmental conditions.     

Kiwifruit micropropagation through callus shoot-bud induction

Summary A profitable system for the establishment of morphogenic callus cultures and indirect shoot induction and development was accomplished from nodal shoot segments obtained from adult and micropropagated plants of kiwifruit (Actinidia deliciosa [Chev.] Liang and Ferguson, var.deliciosa) cv. “Hayward”. The effects of medium composition, cytokinin levels, dilution of salts, and type of callus derived from the cultured primary explants were studied. Medium composition as well as type of callus greatly affected organogenic responses.     

The hormonal control of accessory reproductive gland development in female Schistocerca gregaria

Allatectomy of adult female Schistocerca gregaria prevents the normal development of the accessory reproductive glands and no secretion is produced. Development of the glands can be restored by the administration of synthetic juvenile hormone and the response is dose-dependent. A continuous supply of hormone is required for maintenance of secretory activity. In the normal developmental sequence the total protein content of the glands remains constant until the time at which vitellogenesis occurs in the terminal oöcytes. As maturation proceeds there is a linear increase in protein content of the glands. The initial increase occurs as a result of cellular changes in the glands and is then followed by an increase due to an accumulation of secretion in the lumina.     

Modification of calf lens crystallins as determined by Gel electrophoresis

Summary Variations in size and charge of calf lens proteins, particularly gamma crystallins, were studied by polyacrylamide gel electrophoresis. Exposure of gamma crystallins to near-UV light in the presence of L-tryptophan produces species of higher electrophoretic mobility and higher retardation. Treatment with urea and sulfonation also produced changes in the retardation co-efficient. The increase of retardation co-efficient of gamma crystallin is interpreted to be a result of conformational changes. Gamma crystallins are particularly sensitive to photo-modification, and this process may be associated with age-related changes in the lens.Supported by research grants from the U.S.P.H.S. EY #00459, a FIGHT-FOR-SIGHT Postdoctoral Research Fellowship (FIGHT-FOR-SIGHT, INC., N.Y.C.) and The Rochester Eye and Human Parts Bank, Inc.     

Cooperative control of translational fidelity by ribosomal proteins in Escherichia coli

Summary Two spontaneous mutants of Escherichia coli strain KMBL-146 selected for resistance to the aminoglycoside antibiotic neamine show severe restriction of amber suppressors in vivo. Purified ribosomes from the mutant strains exhibit low neamine-induced misreading in vitro and a decreased affinity for the related antibiotic streptomycin.Biochemical analysis shows that the mutants each have two modified 30S ribosomal proteins, S12 and S5. In agreement with these results, genetic analysis shows that two mutations are present, neither of which confers resistance to neamine by itself; the mutation located in gene rpxL (the structural gene for protein S12) confers streptomycin dependence but this dependence is suppressed in the presence of the second mutation, located in gene rpxE (the structural gene for protein S5).     

An orthoquinone isolated from Salvia aethiopis

A new orthonaphthoquinone diterpene has been isolated from Salvia aethiopis and given the trivial name aethiopinone. The structure of this natural     

The earliest known estuarine bivalve assemblage, Lower Ordovician of northwestern Argentina

The oldest known estuarine bivalve assemblage is documented from the Lower Ordovician (upper Arenig-lower Llanvirn) Alto del Cóndor Formation, which crops out in the Cordillera Oriental of northwestern Argentina. This unit displays most of the diagnostic sedimentary attributes of estuarine environments. Biotic components include low-diversity trace fossils and a peculiar bivalve fauna consisting of the new genera Konduria, Pseudoredonia, and Pucamya, and the new species Redonia condorensis. This constitutes the earliest known occurrence of bivalves in brackish waters, suggesting that the capability of this clade to colonize estuarine environments developed early in their radiation.