Nutrient uptake relationship to root characteristics of rice

Data on root parameters and distribution are important for an improved understanding of the factors influencing nutrient uptake by a crop. Therefore, a study was conducted on a Crowley silt loam at the Rice Research and Extension Center near Stuttgart, Arkansas to measure root growth and N, P and K uptake by three rice (Oryza sativa L.) cultivars at active tillering (36 days after emergence (DAE)), maximum tillering (41 DAE), 1.25 cm internode elongation (55 DAE), booting (77 DAE) and heading (88 DAE). Soil-root core samples were taken to a depth of 40 cm after plant samples were removed, sectioned into 5 cm intervals, roots were washed from soil and root lengths, dry weights and radii were measured. Root parameters were significantly affected by the soil depth × growth stage interaction. In addition, only root radius was affected by cultivar. At the 0- to 5-cm soil depth, root length density ranged from 38 to 93 cm cm^-3 throughout the growing season and decreased with depth to about 2 cm cm^-3 in the 35- to 40-cm depth increment. The increase in root length measured with each succeeding growth stage in each soil horizon also resulted in increased root surface area, hence providing more exposed area for nutrient uptake. About 90% of the total root length was found in the 0- to 20-cm soil depth throughout the season. Average root radius measured in the 0- to 5-cm and 35- to 40-cm depth increments ranged from 0.012 to 0.013 cm and 0.004 to 0.005 cm, respectively throughout the season. Total nutrient uptake by rice differed among cultivars only during vegetative growth. Differences in total nutrient uptake among the cultivars in the field appear to be related to absorption kinetics of the cultivars measured in a growth chamber study. Published with permission of the Arkansas Agricultural Experiment Station.     

The biotransformation of α-(2, 4, 6-trimethylphenyl) ethylamine by rabbit liver preparations

Microsomal incubation of the parent amine, α-(2, 4, 6-trimethylphenyl) ethylamine, VI, produced imine, II, alcohol, IV, oxime, V, and several unknowns. The isolation of imine, II, produces evidence that imines may be involved in the microsomal deamination of primary amines. Separate incubations of the imine, II, produced oxime, V, and several unknowns, one of which is tentatively identified as the nitro derivative. Incubation of the oxime, V, gave the alcohol, IV, the “nitro” metabolite as above and 2 unknowns. Incubation of the hydroxylamine, VII, gave oxime, V, alcohol, IV, 2 unknowns and the “nitro” metabolite.     

Spatial patterns of the frog Oophaga pumilio in a plantation system are consistent with conspecific attraction

The conspecific attraction hypothesis predicts that individuals are attracted to conspecifics because conspecifics may be cues to quality habitat and/or colonists may benefit from living in aggregations. Poison frogs (Dendrobatidae) are aposematic, territorial, and visually oriented—three characteristics which make dendrobatids an appropriate model to test for conspecific attraction. In this study, we tested this hypothesis using an extensive mark‐recapture dataset of the strawberry poison frog (Oophaga pumilio) from La Selva Biological Station, Costa Rica. Data were collected from replicate populations in a relatively homogenous Theobroma cacao plantation, which provided a unique opportunity to test how conspecifics influence the spatial ecology of migrants in a controlled habitat with homogenous structure. We predicted that (1) individuals entering a population would aggregate with resident adults, (2) migrants would share sites with residents at a greater frequency than expected by chance, and (3) migrant home ranges would have shorter nearest‐neighbor distances (NND) to residents than expected by chance. The results were consistent with these three predictions: Relative to random simulations, we observed significant aggregation, home‐range overlap, and NND distribution functions in four, five, and six, respectively, of the six migrant–resident groups analyzed. Conspecific attraction may benefit migrant O. pumilio by providing cues to suitable home sites and/or increasing the potential for social interactions with conspecifics; if true, these benefits should outweigh the negative effects of other factors associated with aggregation. The observed aggregation between migrant and resident O. pumilio is consistent with conspecific attraction in dendrobatid frogs, and our study provides rare support from a field setting that conspecific attraction may be a relevant mechanism for models of anuran spatial ecology.     

滇金丝猴（Rhinopithecusbieti）现状及其保护对策研究

滇金丝猴（Ｒｈｉｎｏｐｉｔｈｅｃｕｓｂｉｅｔｉ）是我国特有的珍稀濒危动物,生活在海拔３８００～４３００ｍ的原始冷杉林中,但有时也会在４３００～４７００ｍ的低矮灌丛、草甸和流石滩上活动达数小时之久,甚至能跨越近千米的无林高海拔地带,因而它们是海拔分布最高的非人灵长类。松萝是它们的主要食物,取食松萝的时间占总取食时间的９１％。猴群活动范围可达近百平方公里。笔者在历时８年的野外考察中,已查明这一物种的全部现存自然种群只有１３个,分布在云南的德钦、兰坪、潍西、丽江和西藏的芒康这五县境内,其现存种群数量为１０００～１５００只;所有现存自然种群几乎均处在相互隔离的状态,群间已不可能进行基因交流,充分表明它们已到达灭绝边缘。然而其栖息地内的商业伐木规模仍在继续扩大,周围的人口压力正在不断增加,各猴群均面临不同程度的偷猎压力。这一现状委实令人担忧。如何拯救这一“国宝”应引起我国保护学家和各级政府有关职能部门的重视     

An Enhanced Packaging System for Helper-Dependent Herpes Simplex Virus Vectors

Helper-dependent herpes simplex virus (HSV) vectors (amplicons) show considerable promise to provide for long-term transduced-gene expression in most cell types. The current packaging system of choice for these vectors involves cotransfection with a set of five overlapping cosmids that encode the full HSV type 1 (HSV-1) helper virus genome from which the packaging (pac) elements have been deleted. Although both the helper virus and the HSV amplicon can replicate, only the latter is packaged into infectious viral particles. Since the titers obtained are too low for practical application, an enhanced second-generation packaging system was developed by modifying both the helper virus and the HSV amplicon vector. The helper virus was reverse engineered by using the original five cosmids to generate a single HSV-bacterial artificial chromosome (BAC) clone in Escherichia coli from which the pac elements were deleted to generate a replication-proficient but packaging-defective HSV-1 genome. The HSV amplicon was modified to contain the simian virus 40 origin of replication, which acts as an HSV-independent replicon to provide for the replicative expansion of the vector. The HSV amplicon is packaged into infectious particles by cotransfection with the HSV-BAC helper virus into the 293T cell line, and the resulting cell lysate is free of detectable helper virus contamination. The combination of both modifications to the original packaging system affords an eightfold increase in the packaged-vector yield.     

The Role of Electron Affinity in Determining Whether Fullerenes Catalyze or Inhibit Photooxidation of Polymers for Solar Cells

Understanding the stability and degradation mechanisms of organic solar materials is critically important to achieving long device lifetimes. Here, an investigation of the photodegradation of polymer:fullerene blend films exposed to ambient conditions for a variety of polymer and fullerene derivative combinations is presented. Despite the wide range in polymer stabilities to photodegradation, the rate of irreversible polymer photobleaching in blend films is found to consistently and dramatically increase with decreasing electron affinity of the fullerene derivative. Furthermore, blends containing fullerenes with the smallest electron affinities photobleached at a faster rate than films of the pure polymer. These observations can be explained by a mechanism where both the polymer and fullerene donate photogenerated electrons to diatomic oxygen to form the superoxide radical anion which degrades the polymer.     

Analysis of X-chromosome inactivation and presumptive expression of the Wiskott-Aldrich syndrome (WAS) gene in hematopoietic cell lineages of a thrombocytopenic carrier female of WAS

Summary We report on a thrombocytopenic female belonging to a pedigree with the Wiskott-Aldrich syndrome (WAS). Restriction fragment length polymorphism (RFLP) analysis with probe M27, closely linked to the WAS gene, demonstrated that she is a carrier of WAS. Both small-sized and normal-sized platelets were present, suggesting that, unlike the vast majority of WAS carriers, she does not manifest nonrandom X-chromosome inactivation in the thrombopoietic cell lineage. Study of X-chromosome inactivation by means of RFLP and methylation analysis demonstrated that the pattern of X-chromosome inactivation was nonrandom in T lymphocytes, but random in granulocytes. While this is the first complete report on the occurrence of thrombocytopenia in a carrier female of WAS as the result of atypical lyonization, it also suggests that expression of the WAS gene occurs at (or extends up to) a later stage than the multipotent stem cell along the hematopoietic differentiation pathway.     

Mouse-adapted SARS-CoV-2 protects animals from lethal SARS-CoV challenge

The emergence of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) has resulted in a pandemic causing significant damage to public health and the economy. Efforts to understand the mechanisms of Coronavirus Disease 2019 (COVID-19) have been hampered by the lack of robust mouse models. To overcome this barrier, we used a reverse genetic system to generate a mouse-adapted strain of SARS-CoV-2. Incorporating key mutations found in SARS-CoV-2 variants, this model recapitulates critical elements of human infection including viral replication in the lung, immune cell infiltration, and significant in vivo disease. Importantly, mouse adaptation of SARS-CoV-2 does not impair replication in human airway cells and maintains antigenicity similar to human SARS-CoV-2 strains. Coupled with the incorporation of mutations found in variants of concern, CMA3p20 offers several advantages over other mouse-adapted SARS-CoV-2 strains. Using this model, we demonstrate that SARS-CoV-2–infected mice are protected from lethal challenge with the original Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV), suggesting immunity from heterologous Coronavirus (CoV) strains. Together, the results highlight the use of this mouse model for further study of SARS-CoV-2 infection and disease.

Studying cross-protection from different coronaviruses is important to inform the research for a universal vaccine. This study uses a mouse-adapted SARS-CoV-2 strain to show that it confers protection from SARS-CoV challenge, suggesting possible immunity from heterologous challenge following natural infection.     

Advances in approaches to seagrass restoration in Australia

Three case studies involving two temperate Australian seagrass species – Pondweed (Ruppia tuberosa) and Ribbon Weed (Posidonia australis) – highlight different approaches to their restoration. Seeds and rhizomes were used in three collaborative programmes to promote new approaches to scale up restoration outcomes.