[32P]orthophosphate and [35S]methionine label separate pools of neurofilaments with markedly different axonal transport kinetics in mouse retinal ganglion cells in vivo

Newly synthesized neurofilament proteins become highly phosphorylated within axons. Within 2 days after intravitreously injecting normal adult mice with [³²P]orthophosphate, we observed that neurofilaments along the entire length of optic axons were radiolabeled by a soluble³²P-carrier that was axonally transported faster than neurofilaments.³²P-incorporation into neurofilament proteins synthesized at the time of injection was comparatively low and minimally influenced the labeling pattern along axons.³²P-incorporation into axonal neurofilaments was considerably higher in the middle region of the optic axons. This characteristic non-uniform distribution of radiolabel remained nearly unchanged for at least 22 days. During this interval, less than 10% of the total³²P-labeled neurofilaments redistributed from the optic nerve to the optic tract. By contrast, newly synthesized neurofilaments were selectively pulse-labeled in ganglion cell bodies by intravitreous injection of [³⁵S]methionine and about 60% of this pool translocated by slow axoplasmic transport to the optic tract during the same time interval. These findings indicate that the steady-state or resident pool of neurofilaments in axons is not identical to the newly synthesized neurofilament pool, the major portion of which moves at the slowest rate of axoplasmic transport. Taken together with earlier studies, these results support the idea that, depending in part on their phosphorylation state, transported neurofilaments can interact for short or very long periods with a stationary but dynamic neurofilament lattice in axons.Special issue dedicated to Dr. Sidney Ochs.     

Identification of a sporulation-specific promoter regulating divergent transcription of two novel sporulation genes in Saccharomyces cerevisiae

Transposition of a new Drosophila retrotransposon was investigated. Total genomic Southern analysis and polytene in situ hybridizations in D. buzzatii strains and other related species using a 6 kb D. buzzatii clone (cDb314) showed a dispersed, repetitive DNA pattern, suggesting that this clone contains a transposable element (TE). We have sequenced the cDb314 clone and demonstrated that it contains all the conserved protein sequences and motifs typical of retrovirus-related sequences. Although cDb314 does not include the complete TE, the protein sequence alignment demonstrates that it includes a defective copy of a new long terminal repeat (LTR) retrotransposon, related to the gypsy family, which we have named Osvaldo. Using a D. buzzatii inbred line in which all insertion sites are known, we have measured Osvaldo transposition rates in hybrids between this D. buzzatii line and its sibling species D. koepferae. The results show that Osvaldo transposes in bursts at high rate, both in the D. buzzatii inbred line and in species hybrids.     

LATE CRETACEOUS FOSSIL FLOWERS OF ERICALEAN AFFINITY

Fossilized flowers of ericalean affinity are reported from the Turanian (ca. 90 MYBP, million years before present) of New Jersey. The fossils are remarkably well preserved and three-dimensional, and are the oldest known floral remains of Ericales. The series of fossil flower buds, floral fragments, and fruits are not identical to any modern genus of Ericales. The inverted U-shaped anthers with pseudoterminal awns, and the fluted syncarpous ovary of the fossils suggest affinities with basal Ericaceae, probably near extant Enkianthus, a taxon that also shares monadinous pollen with the fossil. Pollen grains were observed clumped on a stigma in one of the fossil flowers. Fossilized acid-resistant strands having characteristics, including similar diameter and sculpture pattern, in common with the muri connect pollen grains and, with scanning electron microscopy, appear continuous with the tectum, supporting the interpretation that they are viscin threads. These are the oldest reported fossilized viscin threads, and the only fossilized viscin threads found in situ in flowers. In modern Ericales and Onagraceae, the presence of viscin threads is associated with highly specific plant-pollinator relationships, raising the possibility that such specific pollinator-plant relationships had developed by the mid-Cretaceous. This is consistent with floral characters in these ericalean fossils, the presence of advanced meliponine bees in slightly younger sediments from the same region, and with the morphology and affinities of other fossil flowers from the same sediments.     

A Method for Determining the Activity State of Hair Follicles

A histological method is described for determining the proportion of growing hair follicles h skin samples. A variation of the Sacpic staining method, modified for bulk processing, produces high contrast staining of the principal tissue types present in skin. In particular, the inner root sheath is accentuated, facilitating detection of active follicles. Skin preparations from a range of species are used to illustrate structural characteristics of follicles viewed in cross section at various stages of the hair cycle and to establish criteria for classification of the state of activity of follicles. The hair cycle may be divided into quiescent and active states at the points of rapid transition (early pronanagen and mid catagen). Data from repeated skin biopsies from ferrets and goats are also used to demonstrate quantitative estimation of follicle activity, change in compound follicle size, and the relationship between follicle type and fiber medullation.     

Serum concentrations of reproductively-related circulating steroid hormones in the free-ranging lemon shark,Negaprion brevirostris

Synopsis We have examined the concentrations of reproductively-related steroid hormones in 5 species of carcharhinid sharks, marine fishes possessing the unique attribute of placental viviparity. Measurements of serum estradiol, testosterone, progesterone, dihydrotestosterone, and corticosterone have provided baseline data for these hormones in both immature and adult male and female placental sharks. Our studies include: (1) changes in hormonal levels during maturation, (2) concentrations of circulating steroid hormones during peak breeding season, and (3) hormonal levels during gestation, including the collection of serial samples through and beyond birth from free-ranging lemon sharks. Our data suggest that steroids, important in regulating reproduction in higher mammals, are also essential in these cartilaginous fishes.     

The sialidase superfamily and its spread by horizontal gene transfer

Sialidases (neuraminidases, EC 3.2.1.18) belong to a class of glycosyl hydrolases that release terminal N-acylneuraminate (slalic acid) residues from glycoproteins, glycolipids, and polysaccharides. These enzymes are common in animals of the deuterostomate lineage (Echinodermata through Mammalia) and also in diverse microorganisms that mostly exist as animal commensals or pathogens. Sialidases, and their sialyl substrates, appear to be absent from plants and most other metazoans. Even among bacteria, sialidase is found irregularly so that related species or even strains of one species differ in this property. This unusual phylogenetic distribution makes sialidases interesting for evolutionary studies. The biochemical diversity among bacterial sialidases does not indicate close relationships. However, at the molecular level, homologies are detectable, supporting the hypothesis of a common sialidase origin and thus of a sialidase super family. Some findings indicate that sialidase genes were recently transferred via phages among bacteria. The proposal of a sialidase origin in higher animals is suggested by the presence of apparently homologous enzymes in this kingdom, supporting the idea that some microbes may have acquired the genetic information during association with their animal hosts.     

The early life of Octopus vulgaris (Cephalopoda: Octopodidae) in the plankton and at settlement: a change in lifestyle

Newly hatched young of the benthic, coastal-living octopod, Octopus vulgaris , enter the plankton and remain there for perhaps eight weeks. At hatching the arms are short and bear a few, large, primary suckers. The buccal mass is relatively large in proportion to the size of the animal. The eyes are large. The central nervous system has fairly well-defined lobes, some of which develop earlier than others. We shall follow the development of several features of O. vulgaris from hatching, through its life in the plankton until settlement and correlate them with changes in the brain and behaviour.     

Signal Sequence and Promoter Effects on the Efficacy of Toxin-Expressing Baculoviruses as Biopesticides

Baculovirus recombinants expressing a neurotoxin gene,tox34,from the straw itch mitePyemotes triticihave been previously shown to paralyze or kill insects approximately 50% faster than wild-type. We constructed a series of recombinants of the baculovirusAutographa californicanucleopolyhedrovirus which expressedtox34with different signal sequences or were controlled by different promoters to evaluate their influence on toxin expression in cell culture and in insects. Heterologous signal sequences provided no significant increase in the overall levels of the maturetox34gene product, Tox34, secreted into the tissue culture media from infected cells and no improvement in the time required for paralysis of insect hosts. The time required for paralysis was promoter-dependent; the late 6.9K DNA binding protein gene promoter was generally the most effective promoter, although an insect HSP70 promoter was equally or more effective in one of the species.