Effect of Age-Stiffening Tissues and Intraocular Pressure on Optic Nerve Damages

Age-stiffening of ocular tissues is statistically linked to glaucoma in the elderly. In this study, the effects of age-stiffening on the lamina cribrosa, the primary site of glaucomatous nerve damages, were modeled using computational finite element analysis. We showed that glaucomatous nerve damages and peripheral vision loss behavior can be phenomenologically modeled by shear-based damage criterion. Using this damage criterion, the potential vision loss for 30 years old with mild hypertension of 25mmHg intraocular pressure (IOP) was estimated to be 4%. When the IOP was elevated to 35mmHg, the potential vision loss rose to 45%; and age-stiffening from 35 to 60 years old increased the potential vision loss to 52%. These results showed that while IOP plays a central role in glaucomatous damages, age-stiffening facilitates glaucomatous damages and may be the principal factor that resulted in a higher rate of glaucoma in the elderly than the general population.     

Genbank accession #: AF 135190

Plant Molecular Biology -     

A Dendroctonus bark engraving (Coleoptera: Scolytidae) from a middle Eocene Larix (Coniferales: Pinaceae): early or delayed colonization?

An engraving made by a scolytid bark beetle, assigned to the genus Dendroctonus of the tribe Tomicini, has been identified on a mummified, middle Eocene (45 Ma) specimen of Larix altoborealis wood from the Canadian High Arctic. Larix altoborealis is the earliest known species of Larix, a distinctive lineage of pinaceous conifers that is taxonomically identifiable by the middle Eocene and achieved a broad continental distribution in northern North America and Eurasia during the late Cenozoic. Dendroctonus currently consists of three highly host-specific lineages that have pinaceous hosts: a basal monospecific clade on Pinoideae (Pinus) and two sister clades that consist of a speciose clade associated exclusively with Pinoideae and six species that breed overwhelmingly in Piceoideae (Picea) and Laricoideae (Pseudotsuga and Larix). The middle Eocene engraving in L. altoborealis represents an early member of Dendroctonus that is ancestral to other congeneric species that colonized a short-bracted species of Larix. This fossil occurrence, buttressed by recent data on the phylogeny of Pinaceae subfamilies and Dendroctonus species, indicates that there was phylogenetically congruent colonization by these bark-beetle lineages of a Pinoideae + (Piceoideae + Laricoideae) host-plant sequence. Based on all available evidence, an hypothesis of a geochronologically early invasion during the Early Cretaceous is supported over an alternative view of late Cenozoic cladogenesis by bark beetles onto the Pinaceae. These data also suggest that host-plant chemistry may be an effective species barrier to colonization by some bark-beetle taxa over geologically long time scales.     

Production of compost from marine waste: evaluation of the product for use in ecological agriculture

The sea contains large amounts of resources that are sometimes considered as waste. Such material includes the waste generated by the fish-processing industry and seaweed that is washed up on shores. In this study, these waste products were windrow composted, along with pine bark as a source of carbon and aeration. The final mix proportions were 20 % seaweed, 20 % fish waste, and 60 % pine bark (v/v). After 10 weeks, stable, well-structured, hygienic compost, which was rich in organic matter and nutrients and had a low metal content, was obtained. Tests for maturity, hygiene, and phytotoxicity, along with a detailed physical and chemical characterization, showed that this compost can be used as an organic amendment and/or growth substrate for use in ecological agriculture. The only limiting feature was the high salinity, which could easily be lowered prior to composting the material.     

Novel Insect Leaf-Mining after the End-Cretaceous Extinction and the Demise of Cretaceous Leaf Miners,Great Plains,USA

Plant and associated insect-damage diversity in the western U.S.A. decreased significantly at the Cretaceous-Paleogene (K-Pg) boundary and remained low until the late Paleocene. However, the Mexican Hat locality (ca. 65 Ma) in southeastern Montana, with a typical, low-diversity flora, uniquely exhibits high damage diversity on nearly all its host plants, when compared to all known local and regional early Paleocene sites. The same plant species show minimal damage elsewhere during the early Paleocene. We asked whether the high insect damage diversity at Mexican Hat was more likely related to the survival of Cretaceous insects from refugia or to an influx of novel Paleocene taxa. We compared damage on 1073 leaf fossils from Mexican Hat to over 9000 terminal Cretaceous leaf fossils from the Hell Creek Formation of nearby southwestern North Dakota and to over 9000 Paleocene leaf fossils from the Fort Union Formation in North Dakota, Montana, and Wyoming. We described the entire insect-feeding ichnofauna at Mexican Hat and focused our analysis on leaf mines because they are typically host-specialized and preserve a number of diagnostic morphological characters. Nine mine damage types attributable to three of the four orders of leaf-mining insects are found at Mexican Hat, six of them so far unique to the site. We found no evidence linking any of the diverse Hell Creek mines with those found at Mexican Hat, nor for the survival of any Cretaceous leaf miners over the K-Pg boundary regionally, even on well-sampled, surviving plant families. Overall, our results strongly relate the high damage diversity on the depauperate Mexican Hat flora to an influx of novel insect herbivores during the early Paleocene, possibly caused by a transient warming event and range expansion, and indicate drastic extinction rather than survivorship of Cretaceous insect taxa from refugia.