Leukocyte migration in guinea pigs. II. Partial characterization of a leukocyte migration inhibitory factor distinct from macrophage migration inhibitory factor.

In this study we present data on the partial biological and biochemical characterization of guinea pig leukocyte migration inhibition factor (LIF) and migration inhibition factor (MIF). The results indicate that guinea pig LIF and MIF are distinct mediators of cellular immunity, in terms of indicator cells affected and molecular weight. This is in agreement with previous reports showing distinctions between human LIF and MIF. Partial characterization of guinea pig LIF suggested that it is a heat-stable protein of molecular weight 68,000–158,000 and does not contain terminal sialic acid groups.     

Construction of a plasmid containing the complete coding region of human elongation factor 2.

A plasmid pUChEF-2 containing the coding sequence as well as the complete 3'-untranslated region (3'UTR) of human EF-2 mRNA was constructed. The plasmid construct was assembled from a cDNA insert of pHGR81 (Rapp et al., (1988) Biol. Chem. Hoppe-Seyler 369, 247-250) comprising the C-terminal portion of the coding region and the 3'UTR, as well as a polymer chain reaction PCR fragment (Rapp et al., (1989) Biol. Chem. Hoppe-Seyler 370, 1071-1075) covering the missing part of the coding region from the amino-terminus.     

Rapid enhancement of biodiversity occurrence records using unconventional specimen data

Distributions of taxa across time and space are central to understanding biodiversity and biotic change, yet currently available occurrence data, drawn from biodiversity specimen records and observational datasets, are often insufficient to answer many driving questions. Records of “associated taxa,” taxa co-occurring with a specimen at the time and place of collection, have the potential to fill data gaps and expand the spatiotemporal scope of current occurrence records. I developed a method to extract associated taxon records from 84,328 digitized specimen records and examined the potential of these data to improve the quantity and quality of existing species occurrence data. Adding associated taxon records increased the size of the test dataset by 18.5%, spanned multiple decades (1937–2016), and potentially extended the known range of 217 taxa in Florida and up to 1500 taxa in the United States, demonstrating the capacity of these records to deepen our understanding of changes in the distributions of taxa on Earth. These results suggest that increased attention to documenting associated taxa could be a promising way to maximize the impact of every collecting event.     

Host autophagic degradation and associated symbiont loss in response to heat stress in the symbiotic anemone,Aiptasia pallida

Coral bleaching involves the loss of essential photosynthetic dinoflagellates (Symbiodinium sp.) from host gastrodermal cells in response to temperature or light stress. Although numerous potential cellular bleaching mechanisms have been proposed, there remains much uncertainty regarding which cellular events occur during early breakdown of the host–dinoflagellate symbiosis. In this study, transmission electron microscopy was used to conduct a detailed examination of symbiotic tissues of the tropical anemone Aiptasia pallida during early stages of host stress. Bleaching was induced by exposing specimens to a stress treatment of 32.5±0.5°C at 140±7 μ mol photons m^?2 s^?1 light intensity for 12 h, followed by 12 h at 24±1°C in darkness, repeated over a 48 h period. Ultrastructural examinations revealed numerous dense autophagic structures and associated cellular degradation in tentacle tissues after ~12 h of the stress treatment. Anemones treated with rapamycin, a known autophagy inducer, exhibited the same ultrastructural characteristics as heat‐stressed tissues, confirming that the structures observed during heat stress treatment were autophagic. In addition, symbionts appeared to be expelled from host cells via an apocrine‐like detachment mechanism from the apical ends of autophagic gastrodermal cells. This study provides the first ultrastructural evidence of host autophagic degradation during thermal stress in a cnidarian system and also supports earlier suggestions that autophagy is an active cellular mechanism during early stages of bleaching.     

Unexpected foraminiferal diversity revealed by small-subunit rDNA analysis of Antarctic sediment

Studies of benthic Foraminifera typically rely on the morphological identification of dried specimens. This approach can introduce sampling bias against small, delicate, or morphologically ambiguous forms. To overcome this limitation, we extracted total DNA from sediment followed by PCR using group- and species-specific primers. Phylogenetic analyses revealed that approximately ninety percent of the PCR products represented previously undescribed sequence types that group with undersampled members of the allogromiid Foraminifera. We also used a modification of this technique to track individual species in sediment fractions too fine for normal morphological identification, and to confirm species placement of morphologically ambiguous foraminiferans. We were able to identify the DNA of several large foraminiferal species in fine fractions in a seasonally-dependent manner, indicating that in some seasons the majority of the standing stock of these species exists as gametes/juveniles. The approach outlined here represents a powerful strategy for exploring the total diversity of benthic foraminiferal communities.