Lymphocyte propionyl-CoA carboxylase and accumulation of odd-chain fatty acid in plasma and erythrocytes are useful indicators of marginal biotin deficiency small star,filled

BACKGROUND: Recent studies indicate marginal biotin deficiency is more common than previously thought. That conclusion's validity rests on two indicators of biotin status that depend on renal function.OBJECTIVE: Assessing the validity of two indicators of biotin status that do not depend upon renal function: 1) activity of the biotin-dependent enzyme propionyl-CoA carboxylase (PCC) in lymphocytes and 2) accumulation of odd-chain fatty acids in the lipids of plasma and erythrocytes.DESIGN: Marginal biotin deficiency was induced in 11 healthy adults by egg-white feeding for 28 days. Blood and 24-h urine samples were collected before commencing the diet and twice weekly thereafter. After depletion, biotin status was restored with a general diet with or without 80 &mgr;g/day or 328 nmol/day biotin supplement. Activity of PCC was determined by an optimized NaH 14CO(3) incorporation assay. Fatty acid composition was determined by gas chromatography.RESULTS: With time on the egg-white diet, lymphocyte PCC activity decreased significantly (P <0.0001); C15:0 and C17:0 content increased significantly in the lipids of plasma and erythrocytes (P <0.015). In eight of 11 subjects, lymphocyte PCC activity returned to normal within three weeks of resuming general diets with or without biotin supplement. With repletion, C15:0 and C17:0 in plasma lipids decreased (P <0.02), but odd-chain content of erythrocytes did not decrease significantly.CONCLUSIONS: Lymphocyte PCC activity is an early and sensitive indicator of marginal biotin deficiency. Odd-chain fatty acids accumulate in blood lipids more gradually during marginal deficiency and return to normal more gradually after biotin repletion.     

Ribosomal RNA sequence phylogeny is not congruent with ascospore morphology among species in Ceratocystis sensu stricto

The genus Ceratocystis sensu stricto includes important fungal pathogens of woody and herbaceous plants. This genus is distinguished from species in Ceratocystis sensu lato by the presence of Chalara anamorphs. Ascospore shape has been used extensively in delineating Ceratocystis taxa, which show a large variety of ascospore shapes. Sequence analysis of one region of he 18S ribosomal RNA subunit and two regions of the 28S ribosomal RNA subunit showed that there was a majority of multiple substitutions at nucleotide sites and that there was a low transition/transversion ratio, T = 0.72. Both of these results suggest that these are well established, old species. Ascospore morphology, for the most part, was not congruent with the molecular phylogeny, and the use of morphological characters may be misleading in the taxonomy of these species.      

Ex vivo hemodialysis culture system for assessing the activity of cancer chemotherapeutic agents

Summary An ex vivo culture system was developed for assessing the activity of cancer chemotherapeutic agents against tumor cells. The system utilizes artificial capillary culture units and the technique of hemodialysis to expose tumor cells to a chemotherapeutic drug and its metabolites following injection of the drug into an experimental animal. This ex vivo culture system was used to test the activity of 5-fluorouracil (5-FU) against four human colorectal adenocarcinoma cell lines (SW 403, SW 480, SW 620, and SW 707). Cell killing by 5-FU or its metabolites in blood dialysate following intravenous injection was measured by determining colony formation of cells attached to plastic and suspended in 0.3% agar after short-term exposures of 1 to 2 h. The technique was shown to discriminate between the sensitivities of these cell lines and the respective sensitivities to the drug were reproducible. Kinetics of drug clearance from the host animal’s blood were shown to be similar to that in humans. The results suggest the system may be useful for testing diverse drugs, including those requiring metabolic activation, against a variety of types of tumor cells. Presented in part at the 31st Annual Meeting of the Tissue Culture Association, St. Louis, Missouri, June 1–5, 1980.     

Giemsa-based cytological assessment of area,shape and nucleus:cytoplasm ratio of goblet cells of rabbit bulbar conjunctiva

Goblet cells were visualized in impression cytology specimens from bulbar conjunctiva of the rabbit eye using Giemsa staining. Highly magnified images were used to generate outlines of the goblet cells and their characteristic eccentric nuclei. Using sets of 10 cells from 15 cytology specimens, I found that the longest dimension of the goblet cells averaged 16.7 ± 2.3 μm, the shortest dimension averaged 14.4 ± 1.8 μm and the nucleus averaged 6.3 ± 0.8 μm. The goblet cells were ellipsoid in shape and the longest:shortest cell dimension ratio averaged 1.169 ± 0.091. The goblet cell areas ranged from 108 to 338 μm² (average 193 ± 50 μm²). The area could be predicted reliably from the longest and shortest dimensions (r² = 0.903). The areas of goblet cell nuclei were 15–58 μm² (average 33 ± μm²) and the nucleus:cytoplasm area fraction was predictably greater in smaller goblet cells and less in the larger goblet cells (Spearman correlation = 0.817). The nuclei were estimated to occupy an average of 9.5% of the cell volume. The differences in size, shape and nucleus:cytoplasm ratio may reflect differences in goblet cell maturation.     

Presence of Breeding Birds Improves Body Condition for a Crocodilian Nest Protector

Ecological associations where one species enhances habitat for another nearby species (facilitations) shape fundamental community dynamics and can promote niche expansion, thereby influencing how and where species persist and coexist. For the many breeding birds facing high nest-predation pressure, enemy-free space can be gained by nesting near more formidable animals for physical protection. While the benefits to protected species seem well documented, very few studies have explored whether and how protector species are affected by nest protection associations. Long-legged wading birds (Pelecaniformes and Ciconiiformes) actively choose nesting sites above resident American alligators (Alligator mississippiensis), apparently to take advantage of the protection from mammalian nest predators that alligator presence offers. Previous research has shown that wading bird nesting colonies could provide substantial food for alligators in the form of dropped chicks. We compared alligator body condition in similar habitat with and without wading bird nesting colonies present. Alligator morphometric body condition indices were significantly higher in colony than in non-colony locations, an effect that was statistically independent of a range of environmental variables. Since colonially nesting birds and crocodilians co-occur in many tropical and subtropical wetlands, our results highlight a potentially widespread keystone process between two ecologically important species-groups. These findings suggest the interaction is highly beneficial for both groups of actors, and illustrate how selective pressures may have acted to form and reinforce a strongly positive ecological interaction.     

Heterogeneity and specificity of human anti-insulin antibodies determined by isoelectric focusing

Anti-insulin antibodies are present in the majority of insulin treated diabetics, and in some cases these antibodies have been found to be highly specific for limited epitopes on the molecule. To determine how the human response differs from that seen in inbred animals, we have examined the heterogeneity and specificity of human anti-insulin antibodies by isoelectric focusing (IEF). In addition, we have used human insulin to examine the extent of autoreactivity in the serum of subjects treated with animal insulins. The majority of diabetic sera exhibited complex IEF spectra that were composed of discrete bands and unresolved smears. Autoradiography using 125I-beef, pork, and human insulin revealed some affinity differences; however, the predominant antibodies were capable of binding all insulins, including human. These specificity studies were extended by comparing competitive inhibition with excess cold insulins, and sera with highly specific binding of the A chain loop of beef insulin were identified. The spectra by IEF of these highly specific sera were found to be variable. Our results indicate that the majority of insulin-treated diabetics develop a heterogeneous antibody response that is more complex than the response of inbred animals and includes reactivity with autologous insulin. Although infrequent, individuals having antibodies directed at limited regions of the molecule can be identified and will provide valuable tools for dissecting this complex response.