Major plant communities of warm North American deserts

Abstract. A syntaxonomic study of the major plant communities in neotropical North American deserts (Sonoran, Mojave and Baja California Deserts) is presented. The field method of the Braun-Blanquet approach was combined with a numerical syntaxonomical analysis (cluster analysis and principal coordinate ordination). 21 associations are described for the first time: Ambrosio chenopodifoliae-Larreetum tridentatae, Acamptopappo sphaerocephali-Larreetum tridentatae, Hymenocleo monogyrae-Baccharidetum glutinosae, Bergerocacto emoryi-Agavetum shawii, Burseretum hindsianomicrophyllae, Cercidio microphylli-Carnegieetum giganteae, Bursero microphyllae-Cyrtocarpetum edulis, Hymenocleo salsolae-Daleetum spinosae, Echinocereo engelmannii-Agavetum deserti, Euphorbio californicae-Fouquierietum diguetii, Fouquierio splendentis-Larreetum tridentatae, Agavo cerulatae-Idrietum columnaris, Mascagnio macropterae-Lysilometum candidae, Maytenetum phyllanthoidis, Opuntio basilaris-Larreetum tridentatae, Prosopidetum torreyanae, Roso minutifoliae-Aesculetum parryi, Opuntio taponae-Agavetum subcerulatae, Tidestromio oblongifoliae-Atriplicetum hymenelytrae, Eurotio lanatae-Larreetum tridentatae and Yucco validae-Fouquierietum diguetii. Some associations include subassociations. Ecological, biogeographical and floristic bioclimatic data are given for each association.     

Shrubland formations and associations in mediterranean-desert transitional zones of northwestern Baja California

The area between Ensenada and EI Rosario (Baja California, Mexico) has long been considered as a transitional zone in which two great ecoclimatic regions (Mediterranean and Tropical-Desert) overlap. The floristic and biotypical diversity of this area was evaluated by analyzing its shrubland formations from a phytosociological point of view. This phytosociological study, carried out according to the Braun-Blanquet method and supported by cluster analysis, describes sixteen shrubland associations from Northwestern Baja California.Floristic diversity of the transitional zone was evaluated using two indices, endemic value (EV) and endemic community value (ECV), which are related to the degree of endemism in the flora and plant associations. The phytosociological analysis showed that the high number of shrubland associations found in this area reflected its transitional character. The closer the associations are to the transitional zone, the higher their biotypical and floristic diversity.Abbreviations ADE Adenostoma fasciculatum - AES Fraxinus trifoliata-Aesculus parryi - BER Bergerocactus emoryi-Agave shawii - DES Echinocereus engelmannii-Agave deserti - ENC Viguiera deltoidea-Encelia asperifolia - EUR Eurotia lanata-Yucca schidigera - FOU Agave cerulata-Fouquieria columnaris - FRA Atriplex julacea-Frankenia palmeri - HYM Baccharis glutinosa-Hymenoclea monogyra - KEC Clematis lasiantha-Keckiella antirrhinoides - LAR Ambrosia chenopodifolia-Larrea tridentata - LYC Ephedra californica-Lycium brevipes - MAH Malosma laurina-Heteromeles arbutifolia - MUN Salvia munzii-Artemisia californica - ROS Rosa minutifolia-Aesculus parryi - SAL Salvia apiana-Viguiera laciniata     

Vegetation formations and associations of the zonobiomes along the North American Pacific coast: from northern California to Alaska

This phytosociological study, carried out according to the Braun–Blanquet method and supported by cluster analysis, describes Walter's zonobiomes along the North American Pacific coast between the California–Oregon state border and Alaska (USA), including some interior zones of British Columbia and the Yukon Territory (Canada). Twenty two floristic associations are identified and each is characterized by a unique floristic combination, a distinctive geographical range and particular bioclimatic or edaphic conditions.     

Hemidecortication selectively alters release of glutamate in perfusates collected from cerebral cortex of unrestrained rats

The effect of hemidecortication on the in vivo release of amino acids was examined in different areas of the cerebral cortex of the freely-moving rat. After one side of the cortex was lesioned by aspiration, four guide tubes for push-pull perfusion were implanted chronically on the contralateral side so as to rest above the frontal, parietal, temporal and occipital areas of the cortex. After 10–14 days elapsed, each of these regions was perfused with an artificial cerebrospinal fluid (CSF) at a rate of 25.0 l/min. Two types of assays were undertaken to determine the release of either newly synthesized amino acids from [¹⁴C]glucose precursor or the actual endogenous content in samples of perfusate. The separation of the [¹⁴C]amino acids was performed by thin layer chromatography, whereas endogenous amino acids were separated by HPLC with electrochemical detection and quantitated in the range of 1.0–10.0 picomoles. When compared to the control group, samples collected in the hemidecorticate rat showed no significant differences in the new synthesis of glutamate, aspartate, glutamine, glycine, and GABA from the precursor. On the other hand, the analysis of the endogenous amino acid neurotransmitters revealed that the levels of glutamic acid and glutamine declined in samples obtained from the parietal and frontal cortex, respectively. These results implicate further the potential role of glutamic acid as a neurotransmitter of interhemispheric connections in the cerebral cortex.     

Regulation of glucose transport in Candida utilis

The transport systems for glucose present in Candida utilis cells, growing in batch and continuous cultures on several carbon sources, have been studied. Two different systems were found: a proton symport and a facilitated diffusion system. The high-affinity symport (Km for glucose about 15 microM) transported one proton per mole of glucose and was partially constitutive, appearing in cells grown on gluconeogenic substrates such as lactate, ethanol and glycerol. It was also induced by glucose concentrations up to 0.7 mM and repressed by higher ones. The level of repression depended on the external glucose concentration at which cells had grown in a way similar to that shown by the maltose-uptake system, so both systems seem to be under a common glucose control. Initial uptake by facilitated diffusion, the only transport system present in cells growing at glucose concentrations higher than 10 mM, showed a complex kinetic dependence on the extracellular glucose concentration. This could be explained either by the presence of at least two different systems simultaneously active, one with a Km around 2 mM and the other with a Km of about 1 M, or by the allosteric or hysteretic behaviour of a single carrier whose apparent Km would oscillate between 2 and 70 mM.     

The Golgi-associated long coiled-coil protein NECC1 participates in the control of the regulated secretory pathway in PC12 cells

Golgi-associated long coiled-coil proteins, often referred to as golgins, are involved in the maintenance of the structural organization of the Golgi apparatus and the regulation of membrane traffic events occurring in this organelle. Little information is available on the contribution of golgins to Golgi function in cells specialized in secretion such as endocrine cells or neurons. In the present study, we characterize the intracellular distribution as well as the biochemical and functional properties of a novel long coiled-coil protein present in neuroendocrine tissues, NECC1 (neuroendocrine long coiled-coil protein 1). The present study shows that NECC1 is a peripheral membrane protein displaying high stability to detergent extraction, which distributes across the Golgi apparatus in neuroendocrine cells. In addition, NECC1 partially localizes to post-Golgi carriers containing secretory cargo in PC12 cells. Overexpression of NECC1 resulted in the formation of juxtanuclear aggregates together with a slight fragmentation of the Golgi and a decrease in K+-stimulated hormone release. In contrast, NECC1 silencing did not alter Golgi architecture, but enhanced K+-stimulated hormone secretion in PC12 cells. In all, the results of the present study identify NECC1 as a novel component of the Golgi matrix and support a role for this protein as a negative modulator of the regulated trafficking of secretory cargo in neuroendocrine cells.     

Forecasting Pollen Concentration by a Two‐Step Functional Model

Summary A functional regression model to forecast the cypress pollen concentration during a given time interval, considering the air temperature in a previous interval as the input, is derived by means of a two‐step procedure. This estimation is carried out by functional principal component (FPC) analysis and the residual noise is also modeled by FPC regression, taking as the explicative process the pollen concentration during the earlier interval. The prediction performance is then tested on pollen data series recorded in Granada (Spain) over a period of 10 years.     

Surprising negative association between IgG1 allotype disparity and anti-adalimumab formation: a cohort study

Introduction

The human monoclonal antibody adalimumab is known to induce an anti-globulin response in some adalimumab-treated patients. Antibodies against adalimumab (AAA) are associated with non-response to treatment. Immunoglobulins, such as adalimumab, carry allotypes which represent slight differences in the amino acid sequences of the constant chains of an IgG molecule. Immunoglobulins with particular IgG (Gm) allotypes are racially distributed and could be immunogenic for individuals who do not express these allotypes. Therefore, we investigated whether a mismatch in IgG allotypes between adalimumab and IgG in adalimumab-treated patients is associated with the development of AAA.

Methods

This cohort study consisted of 250 adalimumab-treated rheumatoid arthritis (RA) patients. IgG allotypes were determined for adalimumab and for all patients. Anti-idiotype antibodies against adalimumab were measured with a regular radio immunoassay (RIA), and a newly developed bridging enzyme linked immunosorbent assay (ELISA) was used to measure anti-allotype antibodies against adalimumab. The association between AAA and the G1m3 and the G1m17 allotypes was determined. For differences between groups we used the independent or paired samples t-test, Mann-Whitney test or Chi square/Fisher's exact test as appropriate. To investigate the influence of confounders on the presence or absence of AAA a multiple logistic regression-analysis was used.

Results

Adalimumab carries the G1m17 allotype. No anti-allotype antibodies against adalimumab were detected. Thirty-nine out of 249 patients had anti-idiotype antibodies against adalimumab (16%). IgG allotypes of RA patients were associated with the frequency of AAA: patients homozygous for G1m17 had the highest frequency of AAA (41%), patients homozygous for G1m3 the lowest frequency (10%), and heterozygous patients' AAA frequency was 14% (P = 0.0001).

Conclusions

An allotype mismatch between adalimumab and IgG in adalimumab-treated patients did not lead to a higher frequency of AAA. On the contrary, patients who carried the same IgG allotype as present on the adalimumab IgG molecule, had the highest frequency of anti-adalimumab antibodies compared to patients whose IgG allotype differed from adalimumab. This suggests that the allotype of adalimumab may not be highly immunogenic. Furthermore, patients carrying the G1m17-allotype might be more prone to antibody responses.     

Exploiting the full power of temporal gene expression profiling through a new statistical test: Application to the analysis of muscular dystrophy data

Background  

The identification of biologically interesting genes in a temporal expression profiling dataset is challenging and complicated by high levels of experimental noise. Most statistical methods used in the literature do not fully exploit the temporal ordering in the dataset and are not suited to the case where temporal profiles are measured for a number of different biological conditions. We present a statistical test that makes explicit use of the temporal order in the data by fitting polynomial functions to the temporal profile of each gene and for each biological condition. A Hotelling T ²-statistic is derived to detect the genes for which the parameters of these polynomials are significantly different from each other.