Chimpanzee feeding ecology and fallback food use in the montane forest of Nyungwe National Park,Rwanda

Almost all primates experience seasonal fluctuations in the availability of key food sources. However, the degree to which this fluctuation impacts foraging behavior varies considerably. Eastern chimpanzees (Pan troglodytes schweinfurthii) in Nyungwe National Park, Rwanda, live in a montane forest environment characterized by lower primary productivity and resource diversity than low‐elevation forests. Little is known about chimpanzee feeding ecology in montane forests, and research to date predominantly relies on indirect methods such as fecal analyses. This study is the first to use mostly observational data to examine how seasonal food availability impacts the feeding ecology of montane forest chimpanzees. We examine seasonal changes in chimpanzee diet and fallback foods (FBFs) using instantaneous scan samples and fecal analyses, supported by inspection of feeding remains. Chimpanzee fruit abundance peaked during the major dry season, with a consequent change in chimpanzee diet reflecting the abundance and diversity of key fruit species. Terrestrial herbaceous vegetation was consumed throughout the year and is defined as a “filler” FBF. In contrast to studies conducted in lower‐elevation chimpanzee sites, figs (especially Ficus lutea) were preferred resources, flowers were consumed at seasonally high rates and the proportion of non‐fig fruits in the diet were relatively low in the current study. These divergences likely result from the comparatively low environmental diversity and productivity in higher‐elevation environments.     

Structural and functional variability among DQ β alleles of DR2 subtypes

Homozygous lymphoblastoid cell lines representing various Dw subtypes of DR2 were examined for polymorphism at the DQ locus by molecular and cellular techniques. The subtypes studied included Dw2, Dw12, and a group heterogenous by cellular typing that we shall refer to as non-Dw2/non-Dw12. Restriction fragment length polymorphism analysis of cell lines representing these subtypes revealed DQ -specific patterns consistent with cellular typing. Two-dimensional gel electrophoresis of DQ molecules from representative cell lines revealed a structural polymorphism of DQ among the three subtypes. The DQ chain migrated to a position that was unique to each subtype and was consistent among various representative cell lines of each subtype. Nucleotide sequence analysis of cDNA clones of DQ from Dw2, Dw12, and non-Dw2/non-Dw12 lines confirmed that the variability resided at the genetic level. Variability was found in the form of numerous scattered nucleotide substitutions throughout the first domain of these alleles. The DQ gene of the non-Dw2/non-Dw12 cell line AZH was further found to be almost identical with the DQ gene of a DR1 line (Bell et al. 1985b), implicating a common evolutionary origin of these alleles. The only difference between these two sequences was due to an apparent gene conversion event at amino acid 57. T-cell cloning experiments resulted in the derivation of Epstein-Barr virus-specific, DQw1-restricted clones that proliferated against only those cell lines that exhibited the DQ gene common to AZH and the DR1 cell line. Thus, the polymorphism among DQ alleles within DR2 results in subtype-specific restriction.     

Blidingia ramifera stat. nov. (Chlorophyta): a new marine alga for eastern North America

Blidingia minima var. ramifera is reported for the first time in eastern North America. It occurs in the Gulf of St. Lawrence, Nova Scotia and in Maine. In the estuary of the West and Rights Rivers (Antigonish Harbour, Nova Scotia) it is the most common intertidal alga and during its maximum growth period (June-August) covers 75–90% of the intertidal zone for several km of shoreline at the mouth of the Rights River. In culture, spore germination and early development were typical of the taxon as described from Europe. The taxon is raised to specific status as Blidingia ramifera stat. nov. Blidingia subsalsa is confirmed from New England based on observations of spore germination in plants from Maine and Connecticut.     

N1-Methyl-2-125I-Lysergic Acid Diethylamide, a Preferred Ligand for In Vitro and In Vivo Characterization of Serotonin Receptors

Methylation of 2-125I-lysergic acid diethylamide (125I-LSD) at the N1 position produces a new derivative, N1-methyl-2-125I-lysergic acid diethylamide (125I-MIL), with improved selectivity and higher affinity for serotonin 5-HT2 receptors. In rat frontal cortex homogenates, specific binding of 125I-MIL represents 80-90% of total binding, and the apparent dissociation constant (KD) for serotonin 5-HT2 receptors is 0.14 nM (using 2 mg of tissue/ml). 125I-MIL also displays a high affinity for serotonin 5-HT1C receptors, with an apparent dissociation constant of 0.41 nM at this site. 125I-MIL exhibits at least 60-fold higher affinity for serotonin 5-HT2 receptors than for other classes of neurotransmitter receptors, with the dopamine D2 receptor as its most potent secondary binding site. Studies of the association and dissociation kinetics of 125I-MIL reveal a strong temperature dependence, with very slow association and dissociation rates at 0 degree C. Autoradiographic experiments confirm the improved specificity of 125I-MIL. Selective labeling of serotonin receptors was observed in all brain areas examined. In vivo binding studies in mice indicate that 125I-MIL is the best serotonin receptor label yet described, with the highest frontal cortex to cerebellum ratio of any serotonergic radioligand. 125I-MIL is a promising ligand for both in vitro and in vivo labeling of serotonin receptors in the mammalian brain.     

In support of the trap hypothesis. Chymotrypsin is not rigidly held in its complex with human alpha 2-macroglobulin

Complexes (2:1) of chymotrypsin with human alpha 2-macroglobulin have been prepared in the presence of 200 mM methylamine such that 90% of the chymotrypsin remains noncovalently bound to the alpha 2-macroglobulin. Reaction of this complex with the active-site-directed spin-labeling reagent 4-[(ethoxyfluorophosphinyl)oxy]-2,2,6,6-tetramethylpiperidinyl+ ++-1-oxy results in nitroxide labeling of the active-site serine residue of the complexed chymotrypsin. Electron spin resonance (ESR) spectra of this complex were recorded at 275 K in buffer and at 263 K in 50% glycerol. At 263 K in 50% glycerol the spectrum is that expected for a rigid glass, whereas at room temperature the ESR spectrum shows that the chymotrypsin is only slightly immobilized compared with free spin-labeled chymotrypsin. These findings are discussed in relation to possible models of inhibition of protease activity by alpha 2-macroglobulin. It is concluded that the trap mechanism of Barrett and Starkey [Barrett, A. J., & Starkey, P. M. (1973) Biochem. J. 133, 709-724] is the only model currently considered that can account for the present findings.     

Depletion of Brain Glutathione in Preweanling Mice by L-Buthionine Sulfoximine

Previous studies indicated that DL-buthionine sulfoximine (DL-BSO), an agent that inhibits the biosynthesis of GSH in liver and other peripheral organs, fails to suppress levels of GSH in the CNS. In the current study, preweanling mice responded to repeated injections of L-BSO with marked declines (79.6-86.5%) of GSH content in brain and spinal cord. In adult mice, the same treatment schedule produced only modest declines (17.8-29.2%) of GSH content in brain and a 55.9% decline in spinal cord. Pretreatment of preweanling mice with L-BSO represents a tool for studying the role of GSH in the CNS.     

Serial studies of autologous antibody reactivity to squamous cell carcinoma of the head and neck

Summary In previous studies we evaluated the incidence and specificity of autologous antibody reactivity against squamous cell carcinoma of the head and neck (SCCHN). We were able to demonstrate that autologous antibody reactivity is present in native sera but was usually of too low a titer to allow further analysis. Dissociation of immune complexes by acidification and ultrafiltration of serum augmented autologous antibody reactivity in nine out of nine autologous systems tested. Native antibody and antibody derived from immune complexes produced by the host and reactive with autologous tumor cells may be directed against physiologically relevant antigens. Therefore, correlations of antibody titers with clinical course may provide insight into the nature of the host response to cancer. In the present analysis, serological studies of six patients with SCCHN were performed with serum samples obtained over many months. Results of serial serological assays were correlated to tumor progression and clinical course. Fluctuations in autologous antibody reactivity were noted over time. In four cases, rises in autologous antibody titers preceded the clinical diagnosis of recurrence by several months. Drops in autologous antibody reactivity were noted in two cases following surgery or radiation therapy. In two cases of long-term survivors, no correlation between antibody reactivity and clinical course was noted. Specificity analysis of the six autologous systems demonstrated reactivity against autologous and allogeneic SCCHN as well as melanoma cell lines. These sera did not react with glioma, neuroblastoma, renal cell, breast, bladder and colon carcinoma cell lines nor with fetal calf serum, pooled lymphocytes, red blood cells and platelets. Autologous serial serological studies may provide a means by which to evaluate the host/tumor relationship in patients with SCCHN.     

The effect of dissolved oxygen on the growth of young-of-the-year winter flounder,Pseudopleuronectes americanus

Synopsis The effects of constant and diurnally fluctuating levels of dissolved oxygen on the growth of young-of-the-year winter flounder,Pseudopleuronectes americanus, were examined under controlled laboratory conditions. Fish were exposed for either 10 or 11 weeks to constant levels of 6.7 (high) and 2.2 (low) mg l^–1, and a diurnal fluctuation, ranging from 2.5 to 6.4 mg 0₂l^–1. Growth rates, calculated for both standard length and weight, for fish exposed to low and diurnally fluctuating levels were significantly reduced (p < 0.001) as compared to those for fish exposed to the high level. Growth rates of fish exposed to the high level were over twice those of fish held under low oxygen conditions. Under fluctuating conditions, fish grew at intermediate rates. Following these exposures, all fish were subsequently held at 7.2 mg Oz l^–1 for five weeks. Growth rates increased over two and a half times for fish previously exposed to the low oxygen level and were significantly (p < 0.001) higher than for the other two groups.