Survey of Evidence for Neurosecretion in Gastropod Molluscs

In gastropods that have been studied, there is some indicationof the presence of neurons with specialized staining propertiesthat are possibly neurosecretory. However, there are no stainsspecific for neurosecretion, and certain cellular inclusionscan simulate secretory products. The presence of elementaryneurosecretory granules does not as such determine neurosecretorystatus since such granules may represent neurotransmitters. Evidence of cyclical secretory activity of so-called neurosecretoryneurons is most frequently related to reproductive phenomena,but there are also instances of control of water balance andhibernation. The existence of neurohemal organs within nerves and commissureshas been described in several species. So-called neuroglandularcomplexes have been reported in association with the nervoussystem. Vesicles incorporated in the central nervous systemmay be sensory rather than glandular. Some caution is neededin estimating secretory activity of these complexes. Possible non-neural endocrine glands adjacent to the centralganglia have been described. In pulmonates granule-laden fibersare associated with the mediodorsal bodies; however, the natureof the neurosecretomotor or neurosecretory-neuropil controlis still unclear, both morphologically and physiologically.     

DEFINING CORE HEALTH SERVICES: THE NEW ZEALAND EXPERIENCE

The New Zealand health service has been extensively changed over the past four years, with the introduction of Jour new Regional Health Authorities, required to purchase services on behalf of the Government from a range of providers. In order to ensure fairness across the four regions a Core Services Committee has been set up to define which services must be purchased. However, no clear agreement has emerged about a "core" and no list, either positive (inclusions) or negative (exclusions) has been defined. Instead general criteria have been suggested and steps have been taken to consult the community on their priorities. This paper describes seven workshops run by the author in an effort to discover how the community would reach decisions on the rationing of scare resources. The outcome of these workshops is that there is virtually no community support for an approach based on the social utility of individuals in need.     

Affinities in C3Cyperus lineages (Cyperaceae) revealed using molecular phylogenetic data and carbon isotope analysis

Maximum likelihood and Bayesian analyses of nrDNA (ETS1f) and plastid DNA (rpl32‐trnL, trnH‐psbA) sequence data are presented for ‘C₃Cyperus’ (Cyperaceae). The term ‘C₃Cyperus’ indicates all species of Cyperus s.l. that use C₃ photosynthesis linked with eucyperoid vegetative anatomy. Sampling comprises 77 specimens of 61 different taxa, representing nearly all previously recognized subdivisions of C₃Cyperus and the segregate genera Courtoisina, Kyllingiella and Oxycaryum. According to our results, the Cyperus clade is divided in six well‐supported clades. The first of these clades (clade 1) forms three subclades largely corresponding to Cyperus sections Haspani, Incurvi and Diffusi. Clade 2 comprises the entirely New World C. section Luzuloidei sensu Denton (1978). Clade 3 is a highly diverse clade including two subclades: clade 3a, C. sections Pseudanosporum and Anosporum plus the segregate genera Courtoisina and Oxycaryum; and clade 3b, C. section Fusci. Clade 4 corresponds to C. section Alternifolii and clade 5 to C. section Leucocephali plus the segregate genus Kyllingiella. The sixth clade is a well‐supported monophyletic clade encompassing all C₄Cyperus s.l. species (‘C₄Cyperus’). This study establishes a phylogenetic framework for future studies. © 2011 The Linnean Society of London, Botanical Journal of the Linnean Society, 2011, 167 , 19–46.     

A New Divergent Type of Eukaryotic Methionine Adenosyltransferase is Present in Multiple Distantly Related Secondary Algal Lineages

ABSTRACT. S‐adenosylmethionine is one of the most important metabolites in living cells and is synthesized in a single reaction catalyzed by methionine adenosyltransferase (MAT). At the sequence and structural level, this enzyme is one of the most conserved proteins known. Here we show that some representatives of three distantly related eukaryotic lineages—dinoflagellates, haptophytes, and euglenids—possess a highly divergent type of MAT, which we call MATX. Even though MATX contains all the sites known to be involved in catalysis and the association of monomers, it also has four insertions throughout the protein that are not observed in other MAT homologs. The phylogenetic distribution and affinities of MATX suggest that it originated in a single eukaryotic lineage and was spread via multiple events of eukaryote‐to‐eukaryote lateral gene transfer. We suggest a tentative model in which the origin of MATX is connected with the progression of secondary endosymbiosis.     

Effects of floods versus low flows on invertebrates in a New Zealand gravel-bed river

1. Floods and low flows are hydrological events that influence river ecosystems, but few studies have compared their relative importance in structuring invertebrate communities. Invertebrates were sampled in riffles and runs at eight sites along 40 km of a New Zealand gravel‐bed river every 1–3 months over 2.5 years, during which time a number of large flood and low flow events occurred. Flows were high in winter and spring, and low in summer and autumn. Four flow‐related variables were calculated from hydrological data: flow on the day of sampling (Q_sample), maximum and minimum flow between successive samples (Q_max and Q_min, respectively), and the number of days since the last bed‐moving flood (N_days). 2. The invertebrate community was summarised by relative densities of the 19 most abundant taxa and four biotic metrics [total abundance, taxon richness, the number of Ephemeroptera, Plecoptera and Trichoptera taxa (i.e. EPT richness), and per cent EPT]. Invertebrate density fluctuated greatly, and was high in summer and autumn, and low during winter and spring. Stepwise multiple regression (SMR) analysis was used to investigate relationships between the invertebrate community and season, flow, habitat and water temperature. 3. Seasonal variables were included in almost 50% of the SMR models, while flow‐related variables were included in >75% of models. Densities of many taxa were negatively correlated to Q_min and Q_max, and positively correlated to N_days, suggesting that while high flows reduced invertebrate densities, densities recovered with increasing time following a flood. Although season and flow were confounded in this study, many of the taxa analysed display little seasonal variation in abundance, suggesting that flow‐related variables were more important in structuring communities than seasonal changes in density associated with life‐cycles. 4. Five discrete flood and low flow events were identified and changes to invertebrate communities before and after these events examined. Invertebrate densities decreased more commonly after floods than after low flows, and there was a significant positive relationship between the number of taxa showing reductions in density and flood magnitude. Densities of most invertebrates either remained unchanged, or increased after low flow events, except for four taxa whose densities declined after a very long period (up to 9 months) of low flow. This decline was attributed to autogenic sloughing of thick periphyton communities and subsequent loss of habitat for these taxa. 5. Invertebrate communities changed more after floods and the degree of change was proportional to flood magnitude. Community similarity increased with increasing time since the last disturbance, suggesting that the longer stable flows lasted, the less the community changed. These results suggest that invertebrate communities in the Waipara River were controlled by both floods and low flows, but that the relative effects of floods were greater than even extended periods of extreme low flow. 6. Hydraulic conditions in riffles and runs were measured throughout the study. Riffles had consistently faster velocities, but were shallower and narrower than runs at all measured flows. Invertebrate density in riffles was expressed as a percentage of total density and regressed against the flow‐related variables to see whether invertebrate locations changed according to flow. Significant negative relationships were observed between the per cent density of common taxa in riffles and Q_sample, Q_max and Q_min. This result suggests either that these animals actively drifted into areas of faster velocity during low flows, or that their densities within riffles increased as the width of these habitats declined.     

Cytotoxic Activity <Emphasis Type="Italic">in vitro</Emphasis> of Thymus-derived Lymphocytes Sensitized to Xenograft Antigens

THE importance of the participation of thymus-derived lymphocytes in both humoral antibody production^1,2 and cell-mediated anti-allograft immunity³ has been clearly demonstrated. Evidence for the involvement of thymus-derived cells in the rejection of xenografts is, however, largely indirect. In mice, antilymphocyte serum (ALS) prolongs the survival of xeno-grafted skin⁴ and promotes the growth of tumour xenograft⁵. This can be taken to imply that thymus-derived cells are involved in the rejection process because ALS is known to deplete preferentially the thymus-dependent areas of lymphoid tissue⁶. Raff⁷ has also shown that in ALS treated mice the percentage of theta (θ) positive cells in lymphoid organs is decreased.     

An oscillation underlying feeding and a number of other behaviours in fifth-instar Locusta migratoria nymphs

ABSTRACT. Behavioural evidence is presented for the presence of an oscillation underlying feeding and a number of other activities in fifth-instar Locusta migratoria nymphs raised and observed under LD 12:12 with constant access to food. With the oscillation represented for convenience as a sine wave, these behaviours occurred significantly more often in the peak half of the cycle than in the trough half. The period of the oscillation differed between insects, the range being from 12.0 to 16.5 min, but was constant for each insect. Feeding did not occur on every cycle but when it did occur it usually began near the peak of an oscillation. Off-peak feeding was generally associated with defecation. Other more frequently exhibited behaviours, such as the initiation of locomotion and a variety on non-locomotory behaviours, occurred on peaks when there was no feeding. Once feeding or locomotion had commenced and during the short period of settling afterwards, rhythmicity in the non-locomotory behaviour was lost. The nature of the oscillator is not known, other than it is apparently endogenous and is not reset during a 12-h light phase. The presence of such an intermediate length oscillator may have important implications in the organization of complex behaviour