Revision of species of Minerisporites, Azolla and associated plant microfossils from deposits of the Upper Palaeocene and Palaeocene/Eocene transition in the Netherlands, Belgium and the USA.

Species of the megaspore genus Minerisporites Potonié, megaspore apparatuses of species of the water fern Azolla Lamarck, and some associated organic-walled microfossils recovered from deposits of the Upper Palaeocene and Palaeocene/Eocene transition in the southern part of the Netherlands and neighbouring Belgium are redescribed on the basis of an examination of specimens under scanning and transmission electron microscopes. Originally studied about 40 years ago by S.J. Dijkstra, the re-examination has enabled emended diagnoses to be produced for six taxa: Minerisporites glossoferus (Dijkstra) Tschudy, M. mirabilis (Miner) Potonié, M. mirabilissimus (Dijkstra) Potonié, Azolla schopfii Dijkstra, A. teschiana Florschütz, and A. velus (Dijkstra) Jain and Hall. In addition, a revised description is provided for massulae of Salvinia Séguier that were originally thought to be megaspores and, hence, named by Dijkstra as Triletes? exiguus. The gross morphology and construction of the exospore of the species of Minerisporites are similar, but nevertheless sufficiently distinct for them to be maintained as separate taxa. Monolete microspores are preserved in hollows in the reticulate surface of some of the specimens of M. mirabilissimus. This is consistent with the presumed isoetalean affinity of Minerisporites. An apparent stratigraphic morphocline from M. glossoferus to M. mirabilis, suggested previously, is confirmed following our reassessment of their characteristics. The species of Azolla are all multi-floated, but they differ from each other in several ways, in particular with respect to the ultrastructure of the megaspore wall. They are also distinct from all other species that have been considered in sufficient detail for satisfactory comparisons to be made. The massulae of A. teschiana are described for the first time. The floats in A. velus are attached to the proximal part of the megaspore only by suprafilosal hairs. There are no maniculae. It is argued that these structures do not exist in either this or any other species of Azolla. Whole fertile fossil remains that demonstrate the nature and habitat of the living plants are known for all three genera. Hence, their reproductive structures can be used with confidence in palaeoenvironmental interpretation. The overall assemblage, which also includes a few specimens of the marsilealean megaspore Molaspora lobata (Dijkstra) Hall, undoubtedly reflects the presence of lowland aquatic and semi-aquatic vegetation.

Ultrastructural interpretation of the Late Cretaceous megaspore Glomerisporites pupus and its associated microspores.

The ultrastructure of the Late Cretaceous (Santonian-?early Campanian) megaspore Glomerisporites pupus and its associated microspores has been examined in an attempt to resolve a number of problems concerning the interpretation of their morphology. The new observations presented are based on an analysis of entire, fragmentary, and thin-sectioned specimens under scanning and transmission electron microscopes. These add to, and partly correct, previous observations on this taxon. They include the following: (1) The exine of the megaspore consists of thin, homogeneous, outer undulating and inner electron dense layers, with a thicker zone of spongy structure in-between. (2) The perispore (or perine) of the megaspore comprises four layers, in order towards the exterior: loose filamentous, dense filamentous, vacuolate, and columnar. (3) This is completely enclosed by a thick mat of hairs, which appears to be attached to the underlying perisporal layers by means of connections with a few of the "spines" that originate from the dense filamentous zone, and with some elements of the columnar perine. (4) The tripartite neck (acrolamella) of the spore, which is hidden beneath the mat of hairs, is predominantly an extension of the dense filamentous and vacuolate layers, but also involves the columnar layer, especially in the lower part. (5) Some of the numerous small floats that are embedded in the mat have hairs originating from them. (6) Both long tangled and circinate hairs surround the perispore of the microspores. (7) The exine of the microspore was at least partly attached to the perispore when the organ was viable. (8) It comprises four zones that vary in structure and electron density. These facts and comparisons made with other megaspores and their associated microspores confirm evolutionary links between G. pupus and several taxa included within the Salviniaceae (Azolla, Parazolla, Salvinia) and possible ancestors of this group (the parent plants of Ariadnaesporites and Capulisporites).

Ribonucleases and host defense: identification, localization and gene expression in adherent monocytes in vitro.

Several ribonucleases of the RNase A family function as antibacterial, anti-parasitic and anti-viral agents. In this work, we have shown that mRNAs encoding five of the six known human ribonucleases of the RNase A family are expressed in cultured human monocytes, and that ribonucleases are released by adherent monocytes in culture. Using a polyclonal antiserum prepared against recombinant protein, we have detected one of these ribonucleases, RNase 4, in lysates of normal human peripheral blood monocytes, but not granulocytes or lymphocytes, by Western blotting. Subcellular localization by immunoelectron microscopy demonstrated the presence of RNase 4 in the cytoplasmic granules of isolated monocytes. Interestingly, mRNA encoding RNase 4 could not be detected in freshly isolated monocytes, emerging only after 16 h in culture, suggesting the possibility of de novo protein synthesis in association with monocyte differentiation.

Molecular cloning of four novel murine ribonuclease genes: unusual expansion within the ribonuclease A gene family.

We have characterized four novel murine ribonuclease genes that, together with the murine eosinophil-associated ribonucleases 1 and 2, form a distinct and unusual cluster within the RNase A gene superfamily. Three of these genes (mR-3, mR-4, mR-5) include complete open reading frames, encoding ribonucleases with eight cysteines and appropriately spaced histidines (His11 and His124) and lysine (Lys35) that are characteristic of this enlarging protein family; the fourth sequence encodes a non-functional pseudogene (mR-6P). Although the amino acid sequence similarities among these murine ribonucleases varies from 60 to 94%, they form a unique cluster, as each sequence is found to be more closely related to another of this group than to either murine angiogenin or to murine pancreatic ribonuclease. Interestingly, the relationship between the six genes in this 'mR cluster' and the defined lineages of the RNase A gene family could not be determined by amino acid sequence homology, suggesting the possibility that there are one or more additional ribonuclease lineages that have yet to be defined. Although the nature of the evolutionary constraints promoting this unusual expansion and diversification remain unclear, the implications with respect to function are intriguing.

Informed consent by children and adolescents to psychiatric treatment.

The concept of competency to consent to psychiatric treatment is discussed as a multi-faceted complex interaction involving: the developmental stage of the child and its effect on cognitive ability and rationality; their social environment and previous experience; their relationship with the professional as well as with their own family; the information presented to them about treatment as well as their understanding of that information; and their mental state at the time of deciding. All of these factors exist on a continuum or spectrum (i.e. in shades of grey and not in black and white) and therefore the application of rigid arbitrary limits is inappropriate. What is not in doubt is that the child deserves to be considered as an individual and its rights protected. The doctor's main duty is to the child, as the patient, and every opportunity to allow them to give proper informed consent must be provided. In the event of the child being found to be incompetent to consent, then the issue of proxy consent is also discussed, including the dangers of assuming that the parents will act in the child's best interests.

Effects of soil water deficit on gas exchange characteristics and water relations of orchard lychee (Litchi chinensis Sonn.) trees.

Eight-year-old lychee (Litchi chinensis Sonn.) trees, cv. 'Bengal,' growing in krasnozem soil were subjected to soil water deficit from one month before flowering until harvest by covering the ground with polyethylene sheeting and withholding irrigation. The ratio of daytime stomatal conductance of unirrigated to irrigated trees decreased 20% during the three months of increasing water deficit. Predawn leaf water potentials of irrigated trees averaged about -0.3 MPa throughout the period, whereas they declined progressively to -0.9 MPa in unirrigated trees. Minimum daytime leaf water potential in the unirrigated trees decreased from -1.0 to -1.1 MPa at the beginning of the drought period to -2.2 to -2.4 MPa after three months, and calculated whole-plant conductance did not change with decreasing availability of water. The calculated soil-root water potential declined to less than -1.0 MPa in unirrigated trees. Capacitance effects on the relationship between leaf water potential and transpiration were significant only at low transpiration rates. Although unirrigated trees reduced soil water content at 0-30 cm depths to an equivalent water potential of -1.0 MPa, fruit shedding was significantly less than in irrigated trees. Water deficit had no effect on the fresh weight of pericarp, but caused increased seed size and decreased fresh weight of flesh, resulting in fruit from unirrigated trees being 16% lower in total fresh weight per fruit than fruit from irrigated trees.

Life-saving therapy for newborns: a questionnaire survey in the state of Massachusetts.

The attitudes of Massachusetts pediatricians concerning life-saving therapies for newborns were surveyed. The sample was drawn from the membership list of the Massachusetts Chapter of the American Academy of Pediatrics. Of the sample population of 801 physicians, 449 (56%) responded. Three hypothetical cases were presented with treatment options: (1) An infant with Down syndrome and duodenal atresia, (2) an infant with meningomyelocele and microcephaly and, (3) an extremely low birth weight infant of 700 g and 28 weeks' gestation suffering from birth asphyxia. For case 1, 73% of the physicians recommended surgical correction of the duodenal atresia. Of these, 68% would seek a court order if the parents did not consent to surgery. For case 2, 53% of the physicians recommended surgical repair of the meningomyelocele. For case 3, 90% of the physicians recommended continued resuscitation of the infant and referral to an intensive care unit. Religious affiliation and age were factors influencing these clinical recommendations, with Catholic and younger physicians tending to opt for more aggressive medical intervention. The great majority of physicians (93%) indicated that the economic situation of the family should not affect a decision regarding life-saving therapy. A majority (62%) of the physicians approved of infant care review committees with a primary advisory role. Comparison with earlier attitudinal surveys suggests that pediatricians today are more willing to intervene medically on behalf of infant patients than previously.

Peralkaline volcanicity on the Eurasia Basin margin.

The Kap Washington Group of post-Palaeozoic explosive volcanic rocks was discovered in 1969 on the north coast of Greenland. Although there have been uncertainties regarding their age and chemical character, they have featured prominently in geotectonic reconstructions of the Arctic regions-in recent interpretations as products of the Yermak hot spot, generated on the Nansen spreading axis during the opening of the Eurasia Basin. We present here new evidence which confirms the volcanicity as end-Cretaceous in age and of peralkaline type. We show that a direct connection with the Yermak hot spot is improbable and infer that the volcanic rocks were generated in a continental extensional rift environment before the break-up of the Laurasian plate in the Arctic. Their age helps to constrain the timing of this poorly understood event.

Ethylene and adventitious root formation in hypocotyl segments of etiolated mung-bean (Vigna radiata (L.) Wilczek) seedlings.

Rooting responses and ethylene production by hypocotyl cuttings from etiolated mung-bean seedlings treated with the auxins α-naphthaleneacetic acid, γ-(indole-3)-n-butyric acid (IBA) and 2,4,5-trichloro-phenoxypropionic acid were determined. There was no relationship between the abilities of the auxins to induce root formation and their capacities for inducing ethylene production. Studies with mixtures of 3-indoleacetic acid, a poor stimulator of rooting but an effective inducer of ethylene production, and IBA, an effective rooting stimulator but a poor inducer of ethylene production, exposure of cuttings to ethylene or (2-chloroethyl) phosphonic acid (Ethephon), hypobaric storage (150 mb) of treated cuttings, and exposure of auxin-treated cuttings to 7% CO2 also indicated that ethylene is not directly involved in initiation of adventitious roots in this plant material.