The Arabidopsis HUELLENLOS gene, which is essential for normal ovule development, encodes a mitochondrial ribosomal protein.

The HUELLENLOS (HLL) gene participates in patterning and growth of the Arabidopsis ovule. We have isolated the HLL gene and shown that it encodes a protein homologous to the L14 proteins of eubacterial ribosomes. The Arabidopsis genome also includes a highly similar gene, HUELLENLOS PARALOG (HLP), and genes for both cytosolic (L23) and chloroplast ribosome L14 proteins. Phylogenetic analysis shows that HLL and HLP differ significantly from these other two classes of such proteins. HLL and HLP fusions to green fluorescent protein were localized to mitochondria. Ectopic expression of HLP complemented the hll mutant, indicating that HLP and HLL share redundant functions. We conclude that HLL and HLP encode L14 subunits of mitochondrial ribosomes. HLL mRNA was at significantly higher levels than HLP mRNA in pistils, with the opposite pattern in leaves. This differential expression can explain the confinement of effects of hll mutations to gynoecia and ovules. Our elucidation of the nature of HLL shows that metabolic defects can have specific effects on developmental patterning.

Isolation and characterization of mutants defective in seed coat mucilage secretory cell development in Arabidopsis.

In Arabidopsis, fertilization induces the epidermal cells of the outer ovule integument to differentiate into a specialized seed coat cell type producing extracellular pectinaceous mucilage and a volcano-shaped secondary cell wall. Differentiation involves a regulated series of cytological events including growth, cytoplasmic rearrangement, mucilage synthesis, and secondary cell wall production. We have tested the potential of Arabidopsis seed coat epidermal cells as a model system for the genetic analysis of these processes. A screen for mutants defective in seed mucilage identified five novel genes (MUCILAGE-MODIFIED [MUM]1-5). The seed coat development of these mutants, and that of three previously identified ones (TRANSPARENT TESTA GLABRA1, GLABRA2, and APETALA2) were characterized. Our results show that the genes identified define several events in seed coat differentiation. Although APETALA2 is needed for differentiation of both outer layers of the seed coat, TRANSPARENT TESTA GLABRA1, GLABRA2, and MUM4 are required for complete mucilage synthesis and cytoplasmic rearrangement. MUM3 and MUM5 may be involved in the regulation of mucilage composition, whereas MUM1 and MUM2 appear to play novel roles in post-synthesis cell wall modifications necessary for mucilage extrusion.

Necrospermia and chronic spinal cord injury.

OBJECTIVE: To determine whether improvement in quality of semen over 4 consecutive days of electroejaculation in men with chronic spinal cord injury (SCI) was consistent with epididymal necrospermia. DESIGN: Prospective study of a random sample of men with SCI. SETTING: A southeastern Australian SCI management center in collaboration with the specialist andrology service of a university-based department of obstetrics and gynecology in a tertiary referral hospital. PATIENT(S): Nine men with chronic spinal cord injury. INTERVENTION(S): Semen samples were obtained by using electroejaculation, and testicular biopsy samples were obtained by using fine-needle tissue aspiration. MAIN OUTCOME MEASURE(S): Semen analysis was performed according to World Health Organization criteria. Testicular biopsy and electron microscopy were done by using standard techniques. RESULT(S): During up to 4 days of consecutive-day electroejaculation, sperm motility and viability in semen obtained from men with chronic SCI increased by an average of 23% on days 2 and 3. The severity of the degenerative changes and the numbers of spermatozoa affected on day 1 became less marked by day 4. The changes were not present in late spermatids obtained from testicular biopsies. CONCLUSION(S): The asthenospermia of chronic SCI is similar to epididymal necrospermia and can be improved by consecutive-day electroejaculation.

Differentiation of mucilage secretory cells of the Arabidopsis seed coat.

In some plant species, including Arabidopsis, fertilization induces the epidermal cells of the outer ovule integument to differentiate into a specialized seed coat cell type with a unique morphology and containing large quantities of polysaccharide mucilage (pectin). Such seed coat mucilage cells are necessary for neither viability nor germination under normal laboratory conditions. Thus, the Arabidopsis seed coat offers a unique system with which to use genetics to identify genes controlling cell morphogenesis and complex polysaccharide biosynthesis and secretion. As a first step in the application of this system, we have used microscopy to investigate the structure and differentiation of Arabidopsis seed coat mucilage cells, including cell morphogenesis and the synthesis, secretion, and extrusion of mucilage. During seed coat development in Arabidopsis, the epidermal cells of the outer ovule integument grow and differentiate into cells that produce large quantities of mucilage between the primary cell wall and plasma membrane. Concurrent with mucilage production, the cytoplasm is shaped into a column in the center of the cell. Following mucilage secretion the cytoplasmic column is surrounded by a secondary cell wall to form a structure known as the columella. Thus, differentiation of the seed coat mucilage cells involves a highly regulated series of events including growth, morphogenesis, mucilage biosynthesis and secretion, and secondary cell wall synthesis.

Collection of semen from men in acute phase of spinal cord injury.

In chronic spinal cord injury, semen obtained by assisted ejaculation is usually abnormal. We have assessed electroejaculation early after injury in seven patients. There were no adverse effects. Initial samples contained few or no spermatozoa but as patients emerged from spinal shock, semen improved and five had specimens cryopreserved. Thereafter sperm motility and viability decreased towards the pattern of chronic spinal cord injury by day 16. Cryopreservation was not possible in one patient with many medical complications and another who started electroejaculation 15 days after injury. Semen storage within the first 2 weeks after spinal cord injury is recommended for future fertility treatment.

A simple technique to prevent retrograde ejaculation during assisted ejaculation.

The aim of this study was to develop a technique which would prevent retrograde ejaculation in chronic spinal cord injured (SCI) patients undergoing vibration and electroejaculation procedures. A balloon catheter was used to tamponade the bladder neck in 12 patients who underwent 100 assisted ejaculation procedures. Antegrade ejaculations were collected on all occasions with no incidences of urine contamination and no sperm were seen in post ejaculatory urine. Silicone catheters had minimal effects on sperm motility and viability. All lubricant gels were found to adversely affect sperm quality and were not used.

Evidence for bluetongue virus in Canada: 1976-1979.

Since the identification of approximately 1 400 bovine serological reactors to bluetongue virus in the Okanagan Valley of British Columbia in 1976, there has been no evidence of virus establishment in Canada. No clinical signs suggestive of bluetongue were observed. It was not possible to demonstrate viral activity at the time the seropositive animals were detected and subsequent serological testing supports the hypothesis that the virus has not become endemic or indeed survived in Canadian cattle populations. This combined with the dramatic reduction in prevalence of serological reactors in the years following the initial slaughter suggests that viral activity occurred in the Okanagan Valley prior to 1976 and disappeared. There has been no evidence for transmissions different from that expected of a classical arbovirus; that is, no evidence of "vertical" transmission.