Effect of azetidine 2-carboxylic Acid on ion uptake and ion release to the xylem of excised barley roots

Azetidine 2-carboxylic acid (AZ) was used as an analog of proline to investigate further the relationship between protein synthesis and ion transport. AZ does not inhibit protein assembly, but the proteins formed are ineffective as enzymes. At relatively low concentrations (50 μM) AZ was a potent inhibitor of release of ions to the xylem of excised roots of barley (Hordeum vulgare L.) and intact plants. Uptake to the root was also inhibited but to a lesser degree. A procedure was introduced for estimating unidirectional fluxes from measurements of net tracer uptake, net transport to the xylem, and net efflux from the roots. It was shown that inhibition of release to the xylem was not caused by reduction in influx at the plasmalemma or to stimulation of influx to the vacuoles. It was suggested that AZ was acting on the process of release from symplast to the xylem. The action of AZ is compared with similar effects on ion transport produced by p-fluorophenylalanine, cycloheximide, and abscisic acid.     

Are all species necessary to reveal ecologically important patterns?

While studying ecological patterns at large scales, ecologists are often unable to identify all collections, forcing them to either omit these unidentified records entirely, without knowing the effect of this, or pursue very costly and time‐consuming efforts for identifying them. These “indets” may be of critical importance, but as yet, their impact on the reliability of ecological analyses is poorly known. We investigated the consequence of omitting the unidentified records and provide an explanation for the results. We used three large‐scale independent datasets, (Guyana/ Suriname, French Guiana, Ecuador) each consisting of records having been identified to a valid species name (identified morpho‐species – IMS) and a number of unidentified records (unidentified morpho‐species – UMS). A subset was created for each dataset containing only the IMS, which was compared with the complete dataset containing all morpho‐species (AMS: = IMS + UMS) for the following analyses: species diversity (Fisher's alpha), similarity of species composition, Mantel test and ordination (NMDS). In addition, we also simulated an even larger number of unidentified records for all three datasets and analyzed the agreement between similarities again with these simulated datasets. For all analyses, results were extremely similar when using the complete datasets or the truncated subsets. IMS predicted ≥91% of the variation in AMS in all tests/analyses. Even when simulating a larger fraction of UMS, IMS predicted the results for AMS rather well. Using only IMS also out‐performed using higher taxon data (genus‐level identification) for similarity analyses. Finding a high congruence for all analyses when using IMS rather than AMS suggests that patterns of similarity and composition are very robust. In other words, having a large number of unidentified species in a dataset may not affect our conclusions as much as is often thought.     

Exploring the folding pathway of green fluorescent protein through disulfide engineering

We have introduced two disulfide crosslinks into the loop regions on opposite ends of the beta barrel in superfolder green fluorescent protein (GFP) in order to better understand the nature of its folding pathway. When the disulfide on the side opposite the N/C‐termini is formed, folding is 2× faster, unfolding is 2000× slower, and the protein is stabilized by 16 kJ/mol. But when the disulfide bond on the side of the termini is formed we see little change in the kinetics and stability. The stabilization upon combining the two crosslinks is approximately additive. When the kinetic effects are broken down into multiple phases, we observe Hammond behavior in the upward shift of the kinetic m‐value of unfolding. We use these results in conjunction with structural analysis to assign folding intermediates to two parallel folding pathways. The data are consistent with a view that the two fastest transition states of folding are "barrel closing" steps. The slower of the two phases passes through an intermediate with the barrel opening occurring between strands 7 and 8, while the faster phase opens between 9 and 4. We conclude that disulfide crosslink‐induced perturbations in kinetics are useful for mapping the protein folding pathway.     

Lymphangioma of the pancreas: a multimodal approach to pre‐operative diagnosis

Background: Lymphangioma of the pancreas is an extremely rare benign tumour of lymphatic origin, with only four cases diagnosed by EUS‐FNA reported to date. Methods and materials: Five cases of either cytologically or histologically diagnosed pancreatic lymphangioma with pre‐operative cytological analysis by EUS‐FNAC were reviewed. Results: All patients were female, with a mean age of 56.4 years. By imaging, the cystic lesions ranged in size from 2 to 7 cm (mean 4.5 cm) and were mainly located in the head of the pancreas. All cysts had thin walls and no cyst demonstrated a mural nodule. Diagnosis based on imaging features was benign in all cases due to the absence of high‐risk features. Four samples were sent for biochemical analysis, which showed low CEA levels (range, <0.5–19.4 ng/ml; mean, 5.45 ng/ml) and CA 19.9 and CA 72.4 levels within normal range. All cyst fluids showed numerous small lymphocytes with no atypia; no epithelial cells were present, including no gastrointestinal contamination. Flow cytometry in two cases showed T lymphocytes with a mature phenotype. Surgical resection in two patients confirmed the cytological diagnosis. Benign clinical follow‐up was available in three patients at 2, 3 and 3.5 years. Conclusion: A multimodal approach to cytological diagnosis (combining clinical, radiological and cyst fluid gross, biochemical and cytological characteristics) can lead to the diagnosis of this cystic neoplasm and distinguish it from other more common cysts in the pancreas, potentially avoiding the need for unnecessary surgery.     

Reduced cholesterol and triglycerides in mice with a mutation in Mia2, a liver protein that localizes to ER exit sites

Through forward genetic screening in the mouse, a recessive mutation (couch potato, cpto) has been discovered that dramatically reduces plasma cholesterol levels across all lipoprotein classes. The cpto mutation altered a highly conserved residue in the Src homology domain 3 (SH3) domain of the Mia2 protein. Full-length hepatic Mia2 structurally and functionally resembled the related Mia3 protein. Mia2 localized to endoplasmic reticulum (ER) exit sites, suggesting a role in guiding proteins from the ER to the Golgi. Similarly to the Mia3 protein, Mia2's cytosolic C terminus interacted directly with COPII proteins Sec23 and Sec24, whereas its lumenal SH3 domain may facilitate interactions with secretory cargo. Fractionation of plasma revealed that Mia2(cpto/cpto) mice had lower circulating VLDL, LDL, HDL, and triglycerides. Mia2 is thus a novel, hepatic, ER-to-Golgi trafficking protein that regulates cholesterol metabolism.     

Listeria monocytogenes Associated with New Zealand Seafood Production and Clinical Cases: Unique Sequence Types,Truncated InlA,and Attenuated Invasiveness

Listeriosis is caused by the food-borne pathogen Listeria monocytogenes, which can be found in seafood and processing plants. To evaluate the risk to human health associated with seafood production in New Zealand, multi-virulence-locus sequence typing (MVLST) was used to define the sequence types (STs) of 31 L. monocytogenes isolates collected from seafood-processing plants, 15 from processed foods, and 6 from human listeriosis cases. The STs of these isolates were then compared with those from a collection of seafood isolates and epidemic strains from overseas. A total of 17 STs from New Zealand clustered into two lineages: seafood-related isolates in lineages I and II and all human isolates in lineage II. None of the New Zealand STs matched previously described STs from other countries. Isolates (belonging to ST01-N and ST03-N) from mussels and their processing environments, however, were identical to those of sporadic listeriosis cases in New Zealand. ST03-N isolates (16 from mussel-processing environments, 2 from humans, and 1 from a mussel) contained an inlA premature stop codon (PMSC) mutation. Therefore, the levels of invasiveness of 22 isolates from ST03-N and the three other common STs were compared using human intestinal epithelial Caco-2 cell lines. STs carrying inlA PMSCs, including ST03-N isolates associated with clinical cases, had a low invasion phenotype. The close relatedness of some clinical and environmental strains, as revealed by identical MVLST profiles, suggests that local and persistent environmental strains in seafood-processing environments pose a potential health risk. Furthermore, a PMSC in inlA does not appear to give L. monocytogenes a noninvasive profile.     

Agronomic Considerations for Sweet Sorghum Biofuel Production in the South-Central USA

Sweet sorghum (Sorghum bicolor (L.) Moench) is currently recognized throughout the world as a highly promising biomass energy crop. Production systems and management practices for sweet sorghum have not been fully developed for the USA, although sporadic research efforts during recent decades have provided some insights into production of sweet sorghum primarily for fermentable sugar production. Field plot experiments were conducted at sites across Louisiana to assess biomass and sugar yield responses to N fertilizer, plant density, and selected cultivars. Although linear increases in stem biomass production and fermentable sugar yield were obtained with increasing N fertilizer rate under irrigated conditions, most of the increase was from the initial 45 kg N ha⁻¹ increment. Nitrogen fertilization increased stem biomass production but not fermentable sugar yield in some non-irrigated environments. Increased plant density contributed to fermentable sugar yield only under growth-limiting conditions, particularly under limited soil moisture. Location effects indicate that sweet sorghum may not be suitable for some sub-optimal cropland and pasture environments in Louisiana. During the primary growing season, cultivar did not affect fermentable sugar yields, although Dale was consistently high in sugar concentration during this period. Nitrogen fertilizer increased fermentable sugar yields only when moisture was not limiting. Overall results indicate that in environments where soil moisture limits plant growth, sugar yield responses are likely from increased plant density and not from increased N fertilization.