Nest building by lowland gorillas in the Lopé Reserve,Gabon: Environmental influences and implications for censusing

We analyzed data from 373 fresh nest-sites (containing 2435 nests) of lowland gorillas (Gorilla g. gorilla)during a 4-year period in the Lopé Reserve, Gabon, to determine whether the observed variability in nest building was due to environmental influences. We recognized and defined seven types of nest in terms of the degree of construction and the raw materials used. Overall, nests built on the ground from herbaceous plants are the most common type (40%), followed by tree nests (35%). Frequencies of the different nest-types vary significantly between eight habitat-types. In habitat-types with high densities of understory herbs, ground nests predominated, but when herbs were rare, the majority of nests were in trees. A general preference for sleeping in herbaceous ground nests is indicated since trees are abundant in all habitat-types, except savanna. The frequency of nesting in trees shows a significant positive correlation with rainfall, but effects of climate are confounded by seasonal variation in use of different habitat-types. When elephants were attracted to the same localized food sources as gorillas, many tree nests were built even when herbs were available. We conclude that different nest-types reflect a variety of solutions to maximize comfort, depending on available raw materials and the probability of rainfall or disturbance by elephants or both factors. Nests are a powerful tool for population censuses and demographic studies of great apes, but problems exist in interpreting data on lowland gorilla nests. Results from this analysis show that only a third of nest-sites accurately reflects group size (of weaned individuals) and that 26% of all gorilla nest-sites could be mistaken for those of chimpanzees, as all nests, or all those visible from a transect, were in trees. Gorilla nests at Lopé were nonrandomly distributed with respect to habitat-types, and nest construction varied seasonally, thereby introducing sources of bias to transect nest counts. We discuss these problems and ones related to assessing the decay rate of nest-sites and make recommendations relevant to census work.     

Developing compound eye in lozenge mutants of Drosophila: lozenge expression in the R7 equivalence group

 The lozenge locus is genetically complex, containing two functionally distinct units, cistrons A and B, that influence the structure of the compound eye. Extreme mutations of either cistron produce adult phenotypes that share similarities and that have striking differences. We have analyzed the expression of several developmentally important eye genes including boss, scabrous, rhomboid, seven-up, and Bar in lozenge mutant backgrounds representing both cistrons. This analysis follows the progressive recruitment of photoreceptor neurons during eye development and has confirmed that the initial development of photoreceptors is normal up to the five cell precluster stage (R8, R2/5 and R3/4). However, when lozenge is mutant, further eye development is perturbed. As cells R1, R6 and R7 are recruited, patterns of gene expression for seven-up and Bar become abnormal. We have also characterized the expression of two different enhancer trap alleles of lozenge. The lozenge product(s) appear to be first expressed in the eye disc in undifferentiated cells shortly after the five cell precluster forms. Then, as distinct cells are recruited to a fate, lozenge expression persists and is refined in those cells. Our data suggests that lozenge functions in cone cells and pigment cells as well as in specific glia. With respect to photoreceptor neurons, lozenge biases the developmental potential of cells R1, R6 and R7, by directly influencing the expression of genes important for establishing cell fate. Received: 26 July 1996 / Accepted: 6 January 1997     

Cloning and characterization of a sialidase from the murine histocompatibility-2 complex: low levels of mRNA and a single amino acid mutation are responsible for reduced sialidase activity in mice carrying the Neula allele

The Neu1 locus, in the S region of the murine histocompatibility-2complex, regulates the sialic acid content of several liverlysosomal enzymes. Three alleles, Neu1^a, Neu1^b, and Neu1^c, havebeen described on the basis of differential sialylation of theenzyme liver acid phosphatase. The Neu1^a allele occurs in asmall number of mouse strains, e.g., SM/J and is associatedwith sialidase deficiency. We recently described G9, a sialidasegene in the human major histocompatibility complex (Milner etal. (1997) J. Biol. Chem., 272, 4549–4558), and we nowreport the characterization of the equivalent gene in mouse.The protein product of the murine G9 gene is 409 amino acidsin length and is 83% identical to its human orthologue. Expressionof the murine G9 protein in insect cells has confirmed thatit is a sialidase, with optimal activity at pH 5. To elucidatethe basis of sialidase deficiency in mouse strains carryingthe Neu1^a allele, we have sequenced the G9 coding regions frommice carrying the three Neu1 alleles and hence defined the aminoacid sequence characteristic of each allotype. Of particularinterest is a Leu-209 to Ile mutation that is unique to theNeu1^a allotype and is associated with reductions in sialidaseactivity of 68% and 88% compared to the Neu1^b and Neu1^c allotypes,respectively, when these three protein variants are expressedin insect cells. Additional factors, such as differential expression,may also influence the activities of the Nen1 allotypes in vivo.We have observed that the level of G9 mRNA is substantiallyreduced in mice carrying the Neu1^a allele compared to the Neu1^b(85–95% reduction) and Neu1^c (70% reduction) alleles. H2 complex MHC Neu1 sialidase     

Proteolytic activity of proteasome on myofibrillar structures

The physiologic function of proteasome remains unclear. Evidence suggests a role in degradation of ubiquitin-protein conjugates, MHC antigen presentation, and some specificity of substrate within certain cell types. To explore further the properties of proteasome we have examined its effect on a well defined structure, the myofibril. We find that despite its large size (20S) proteasome is able to degrade myofibrils and intact, permeabilized muscle fibrils. The proteins degraded showed some specificity because actin, myosin and desmin were degraded faster than -actinin, troponin T and tropomyosin. Changes in ultrastructure were slow and included a general loss of structure with Z and I bands effected before the M band and costameres.     

Molecular basis and PCR-DNA typing of the Fya/fyb blood group polymorphism

Spondyloepiphyseal dysplasia tarda (SEDL) is an X-linked recessive disorder characterized in affected males by short stature resulting from a growth defect of the vertebral bodies. We have extended our earlier studies by analyzing 15 families with newly identified microsatellite DNA markers; analysis of recombination events with these markers indicates that the gene responsible for SEDL is located in Xp22 between DXS 16 and DXS 987 on an interval spanning approximately 2 Mb.     

Calmodulin activation of adenylate cyclase in the mouse B16 melanoma.

Calmodulin antagonists inhibited hormone-stimulated cyclic AMP accumulation in both cultured cells and cell lysates of mouse B16 melanoma. Particulate preparations of B16 melanoma contained 34-45% of total cell calmodulin, which could not be dissociated by extensive washing irrespective of the presence of EGTA in the buffer. The adenylate cyclase activity in such preparations was unaffected by the addition of exogenous calmodulin. However, the rare-earth-metal ion La3+, which can mimic or replace Ca2+ in many systems, produced an immediate inhibition of agonist-stimulated adenylate cyclase activity and preincubation of particulate preparations was La3+ followed by washing with La3+-free buffer dissociated calmodulin (96% loss) from particulate preparations. The loss of calmodulin from particulate preparations was associated with a decrease in agonist responsiveness (74%) and a marked change in the Ca2+-sensitivity of the enzyme, low concentrations of calcium (approx. 10 nM) now failing to stimulate enzyme activity, high concentrations of calcium (greater than or equal to 100 nM) producing greater-than-normal inhibition of enzyme activity. Direct activation of adenylate cyclase by the addition of pure calmodulin was now demonstrable in such calmodulin-depleted particulate preparations. Half-maximal stimulation of agonist-responsive adenylate cyclase occurred at 80 nM-calmodulin in the presence of 10 microM free Ca2+. Maximal stimulation by calmodulin (at 300-600 nM) restored enzyme activity to 89 +/- 5% (mean +/- S.E.M., n = 7) of the activity in untreated, calmodulin-intact, preparations.     

Inferior turbinate surgery: an adjunct to successful treatment of nasal obstruction in 408 patients

Septal deviation is often associated with hypertrophy of the contralateral inferior turbinate. Failure to reduce the size of the turbinate at the time of septal reconstruction may result in persistent nasal obstruction. The authors present their experience with 408 patients who underwent one of four turbinate procedures over a 6-year period. Most patients underwent unilateral turbinate surgery, although bilateral procedures were undertaken in 7 percent of patients. A graduated surgical approach was taken that varied according to the amount of turbinate enlargement and the degree to which mucosa and bone were involved. Full-thickness excision of the anterior third to half of the inferior turbinate (turbinectomy) became a favored procedure. Relief of nasal obstruction was obtained in greater than 90 percent of patients. Healing was satisfactory regardless of the method, and complications, including hemorrhage and infection, were few. Long-term follow-up revealed no untoward sequelae, and no patient developed atrophic rhinitis. The authors conclude that turbinate surgery, particularly when unilateral, in the carefully selected patient with nasal obstruction is a useful adjunct to septal surgery.