Exudate-feeding byCallithrix jacchus penicillata in semideciduous woodland (Cerradão) in central Brazil

We report the exudate feeding behavior of two groups of marmosets (Callithrix jacchus penicillata) living permanently in Cerradão, a common woodland formation of Central Brazil. Cerradão is an open canopy formation and marmosets must occasionally descend to the ground in order to move from tree to tree. Even in atypical habitat, exudate eating is the predominant foraging activity. Marmosets are engaged in exudate collection over 70% of the total time spent feeding. They were observed gnawing on seven species of trees, and consumed exudates from four of these species. We compared the degree of utilization of the exudate sources, and examined a number of different characteristics of the exudates. Morphological adaptations that allow for the exploitation of the “exudate-eater niche” may be an important component of the adaptability ofCallithrix marmosets.     

Fractionation of the gene-size macronuclear chromatin fragments of the binucleated eukaryote Oxytricha

Summary The macronuclear chromatin of Oxytrichia nova consists of chromatin fragments which are fully soluble in 0.2 mM EDTA and whose DNA length varies from 500–25 000 bp. The DNA migrates electrophoretically as a series of discrete bands, with specific genes present in only one or a few bands. The chromatin fragments are composed of nucleosomes and migrate electrophoretically in proportion to their DNA length. These results suggest schemes for the fractionation of undigested chromatin in order to enrich for specific genes, facilitating analysis of changes in chromatin structure associated with changes in gene expression.     

Effects of estradiol-17β in the male xenopus laevis: Isolation and translation of cytoplasmic messenger rna populations

Summary Total Xenopus liver cytoplasmic RNA isolated following long-term estrogen administration (14 days) was fractioned using Sepharose 4B chromatography. One of the Sepharose 4B peaks was shown to contain RNA with a molecular weight reported for vitellogenin mRNA (34S). The presence of estrogeninduced vitellogenin mRNA in the peak 5 RNA was determined by translation of the RNA in the oocyte and analysis of the oocyte translational products by immunoprecipitation with anti-vitellogenin.Sepharose 4B peaks 2 and 3 were also observed to contain estrogen induced mRNA populations sedimenting between 9-18S. These findings suggest that Sepharose 4B chromatography might prove useful in separating different mRNA populations following estrogen-induced gene activation.     

Relevance of duration of transient ischaemic attacks in carotid territory.

A retrospective review of the clinical and angiographic features of 116 patients who had had one or more transient ischaemic attacks in the carotid territory showed that stenosis of ther cervical portion of the internal carotid artery was significantly more prevalent among patients whose attacks had been brief, with full recovery in under one hour. This information may be helpful in selecting patients for angiography.     

Failure to detect intra-abdominal metastases from breast cancer: a case for staging laparotomy

Two studies were performed to assess the accuracy of non-invasive methods in detecting intra-abdominal metastases from breast cancer. Firstly, the sites of spread detected at the time of first presentation with metastases were compared with the sites of spread shown at necropsy in the same patients. Although about two-thirds of the patients with bone and lung metastases at necropsy had had metastases detected at these sites when they first presented with metastases, only a third of the patients with liver metastases and none of those with other intra-abdominal metastases had had evidence of disease at first presentation with metastases. The second study confirmed a poor detection rate of liver and other intra-abdominal metastases in patients with breast cancer undergoing laparotomy and oophorectomy who were staged immediately before operation.Pre-mastectomy staging laparotomy should be considered in those patients with primary breast cancer who are most likely to have disseminated disease beyond the regional nodes. In the presence of occult gross metastases detected by staging laparotomy, mastectomy will not provide additional protection against loca recurrence of disease. Patients with occult gross metastases should also be excluded from studies on adjuvant chemotherapy (designed to treat micrometastases). Aggressive methods of staging are justified to protect the patient as far as possible against unnecessary mastectomy and to identify those patients who should be treated by therapeutic chemotherapy rather than adjuvant chemotherapy.     

A fine-structural study of embryonic and larval development in the gymnoblastic hydroid Pennaria tiarella.

1. The pregastrulation blastomers contain electron-dense granules which become localized after gastrulation in the apices of the developing epithelio-muscle cells and persist throughout larval development. The cytoplasm of the blastomeres is organized into anucleate, membrane-delimited lobules. The lobules, which persist until six hours of development, come to contain a single, peripherally located cisterna of granular endoplasmic reticulum. Microvilli are present at the earliest stages examined and persist throughout development. Cilia are first detected at four hours. 2. Gastrulation, marked by the appearance of the mesoglea, occurs between six and eight hours of development. Basal foot processes of epithelio-muscle cells are detected by eight hours, but myonemes cannot be detected until later in development. 3. Immediately following gastrulation, mucous cells begin their differentiation from dividing cells located near the apex of the ectoderm. During their differentiation, the cells elongate toward the mesoglea. 4. By 16 hours post-fertilization, a third cell type can be detected in the ectoderm. The cell, which contains no granules, has an unusual cytoplasmic organization in which fused membranes divide the cytoplasm into parallel compartments containing a single cisterna of granular endoplasmic reticulum. 5. The findings of the present study are correlated with those of previous studies of development in Pennaria and other hydroids. The possible functional roles of the Type I granules, the cytoplasmic lobules, and the nongranular cell are discussed.     

The isolation of new DNA synthesis mutants in the yeast Saccharomyces cerevisiae

Summary Sixty-eight new conditional cell cycle mutants have been isolated on the basis of their terminal cellular morphology (dumbbells). Fifteen mutants falling into nine complementation groups, were grossly defective in DNA replication and have been assigned the provisional gene symboldbf (fordumbbellformer). Dbf1 and2 stop DNA synthesis immediately on transfer to 37°C and are presumably defective in enzymes required for polymerization. Neither, however, possess a thermolabile DNA polymerase A or B.Dbf3 and4 show a pattern of synthesis consistent with their being deficient in initiation of DNA synthesis. This is confirmed in the accompanying paper.The remaining mutants are deficient in the synthesis of RNA as well as DNA. Indeed the four members of one complementation group are allelic withrna3, one of the group of mutants originally isolated as defective in RNA synthesis, and which do not exhibit a cell cycle phenotype. A re-examination of this group of mutants however, showed the bulk of them also to be defective in DNA synthesis. Furthermore, in preliminary experimentsrna3 and our four new alleles of it, together withrna6 anddbf5 and6, showed enhanced spontaneous mutation frequency.