Immunocytochemical detection of a murine leukemia virus-related nuclear antigen in mouse oocytes and early embryos.

The expression of murine leukemia virus (MuLV)-related antigens in oocytes and early embryos of Swiss mice was studied by the unlabeled antibody peroxidase-antiperoxidase method using an antiserum to the major core protein, p30, of AKR MuLV. This procedure resulted in an intense staining, at antibody dilutions up to 1:500, of the germinal vesicles of oocytes and the interphase nuclei of early embryos. Nuclear staining was restricted to a specific period of oocyte growth and embryo development. It developed gradually in oocytes having reached one third to one half the full-grown size and persisted until meiotic maturation. In early embryos, nuclear staining was present from the one-cell stage to the morula, but disappeared during transition from morula to blastocyst and was not seen in expanded blastocysts. Nuclear staining was abolished by absorption of the anti-p30 serum with detergent-disrupted virions of Gross(A), AKR, Kirsten and Moloney MuLV, and Kirsten MSV(MuLV), but not with the Friend and Rauscher strains of MuLV, the xenotropic BALB:virus 2, a mouse tropic and an amphotropic clone of wild mouse MuLV, or with FeLV and RSV. On the basis of these results, it is suggested that the nuclear antigen (termed germinal vesicle antigen) reacting with the anti-p30 serum is the product of a cellular gene having a normal function in early embryonic development, and that sequences related to this gene are incorporated into the genome of AKR-type MuLV.     

Cryptosporidiosis in the V Region Chile. III. Study of malnourished patients, 1985-1987

Frequency of infection by Cryptosporidium sp. in 1,039 faecal smears stained by Ziehl-Neelsen, obtained from undernourished patients of a Nutritional Recovery Center and an ambulatory undernourished center from the Fifth Region, Chile, were studied. All underwent a coproparasitological examination by the modified Telemann method. Thirty eight (3.7%) patients infected by the parasite were detected, with an overall frequency of 8.5% among patients of the Nutritional Recovery Center and 1.9% among the ambulatory patients; this difference was statistically significant. The highest percentage of positive results were detected among the younger milk feeding infants. Also the percentage of difference among these and the older milk feeding infants (3.7%) was statistically significant. Association of Cryptosporidium sp. and Giardia lamblia was observed in 6 ambulatory patients (2.3%).     

Other developments regarding the concept of energy in biological systems

In order to recognize the realizability of inputs with different physical natures through a component, Yoneda's Lemma is applied. The major utility of this Lemma is when the components produce only energy. From this, it is assumed that a new material input must exist which was not recognized in the original developments in biological systems representation. Moreover, simple transfers of energy, between objects, components, and among both objects and components are developed under the generic name; energetical evolution. Thus, energetical evolution appears as anew element in the abstract representation of biological systems. These new concepts are incorporated into a new abstract diagram and a newM _β category. This paper was made possible by a Fellowship from the Consejo Nacional de Investigaciones Científicas y Técnicas of the República Argentina.     

Ribosomal assembly deficiency in an Escherichia coli thermosensitive mutant having an altered L24 ribosomal protein.

Localized P1 mutagenesis was used to screen for conditionally lethal mutations in ribosomal protein genes. One such mutation, 2859mis, has been mapped inside the ribosomal protein gene cluster at 72 minutes on the Escherichia coli chromosome and cotransduces at 98% with rpsE (S5). The 2869mis mutation leads to thermosensitivity and impaired assembly in vivo of 50 S ribosomal particles at 42 °C. The strain carrying the mutation has an altered L24 ribosomal protein which at 42 °C shows weaker affinity for 23 S RNA than the wild-type protein. The mutational alteration involves a replacement of glycine by aspartic acid in protein L24 from the mutant. We conclude therefore that the 2859mis mutation affects the structural gene for protein L24 (rplX).     

FRACTIONATION OF RNA FROM BRAIN SYNAPTOSOMES AND CYTOPLASMIC SUBCELLULAR FRACTIONS

—RNA from rat brain synaptosomes, mitochondria and microsomes was analysed by gel electrophoresis under conditions allowing good resolution in three different molecular weight ranges: 4s-16s, 16s-28s and >28s. Two synaptosome specific RNA bands were found, one with comparatively low molecular weight (8-9 × 10⁴ Daltons) and another very large (s_E > 60s). RNA species with electrophoretic characteristics similar to those reported for liver mitochondrial RNA were found in brain mitochondria. From the electrophoretic data their mean geometric radii were determined.     

Performance of Two Fruit Fly (Diptera: Tephritidae) Pupal Parasitoids (Coptera haywardi [Hymenoptera: Diapriidae] and Pachycrepoideus vindemiae [Hymenoptera: Pteromalidae]) under Different Environmental Soil Conditions

We evaluated the performance of Coptera haywardi (Ogloblin) (Diapriidae) and Pachycrepoideus vindemiae (Rondani) (Pteromalidae), both hymenopteran pupal parasitoids of Anastrepha spp. (Diptera: Tephritidae). Performance was studied by manipulating the following environmental conditions in the laboratory: (1) soil type, (2) soil moisture content, (3) soil compaction, and (4) depth at which pupae were buried in the soil. There were two experiments: in the first, exposure time of pupae was held constant and in the second, it varied. In the first experiment, C. haywardi was significantly more effective than P. vindemiae in parasitizing fly pupae. With exposure time held constant (36 h), only soil type and pupal burial depth were significantly related to parasitism rates. While P. vindemiae only parasitized pupae located on the soil surface, C. haywardi attacked pupae that were buried up to 5 cm deep, performing better in clayey than in loamy soil. In the second experiment, exposure time (24, 36, 48, and 72 h) had no significant effect on parasitism rates, but soil type did. P. vindemiae again only attacked pupae on the soil surface while C. haywardi was also able to parasitize pupae that were buried up to 5 cm deep. We conclude that C. haywardi represents a viable candidate to replace the environmentally unfriendly P. vindemiae in augmentative biological control programs against fruit flies.