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661.
Jose L. Herraiz Joan Rib Hctor Botella Carlos Martínez-Prez Humberto G. Ferrn 《Biology letters》2020,16(11)
Nursery areas are fundamental for the success of many marine species, particularly for large, slow-growing taxa with low fecundity and high age of maturity. Here, we examine the population size-class structure of the extinct gigantic shark Otodus megalodon in a newly described middle Miocene locality from Northeastern Spain, as well as in eight previously known formations (Temblor, Calvert, Pisco, Gatún, Chucunaque, Bahía Inglesa, Yorktown and Bone Valley). In all cases, body lengths of all individuals were inferred from dental parameters and the size-class structure was estimated from kernel probability density functions and Gaussian mixture models. Our analyses support the presence of five potential nurseries ranging from the Langhian (middle Miocene) to the Zanclean (Pliocene), with higher densities of individuals with estimated body lengths within the typical range of neonates and young juveniles. These results reveal, for the first time, that nursery areas were commonly used by O. megalodon over large temporal and spatial scales, reducing early mortality and playing a key role in maintaining viable adult populations. Ultimately, the presumed reliance of O. megalodon on the presence of suitable nursery grounds might have also been determinant in the demise of this iconic top predatory shark. 相似文献
662.
663.
Estimating a founder's genomic proportion for each descendant in an outbred pedigree. 总被引:1,自引:0,他引:1
The question of how to estimate a founder's proportion of a single descendant's genome has renewed relevance for outbred pedigrees, given the abundant DNA sequence data for model and nonmodel eukaryotes alike. Here we show that a donor-recurrent shortcut method can provide a robust estimation of founder proportions. In addition, we define the theoretical variance and estimate confidence intervals using a nonparameteric bootstrap method. Using actual marker data from a highly heterozygous outbred Pinus taeda pedigree, it was found that each founder's genomic proportion varied widely for each descendant, ranging from 8.8% to 38.7%. In 1 case, skewed transmission of a founder's genome could be statistically detected. Its founder proportions ranged from 1.54% to 48.46%, and its mean value was 17.59%, well below the expected value of 25%. Two-thirds of its 91 descendants had 1 or the other founder haplotype, despite 2 successive meioses. The donor-recurrent method was robust; variation for estimated founder's proportions was also wide for simulated high-density datasets whether markers were dispersed or clustered. Estimating founder contributions using this computational shortcut has broad application for highly heterozygous outbred pedigrees characterized by large sibships, low population differentiation, and shallow physical mapping resources. The relevance of this computational shortcut for outbred populations used for conservation, domestication, and evolutionary biology research is discussed. 相似文献
664.
Alejandro López-Cortés Oliverio Rodríguez-Fernández Hever Latisnere-Barragán Humberto C. Mejía-Ruíz Getzabeth González-Gutiérrez Carlos Lomelí-Ortega 《World journal of microbiology & biotechnology》2010,26(1):109-118
Polyhydroxyalakanote (PHA) was produced by the marine bacteria Paracoccus seriniphilus Strain E71. Three methods were used for screening PHA in this strain: (1) microscopic analysis, (2) specifically designed
primers for amplify fragments of phaC gene from Gram negative bacteria, and (3) measurements using spectroscopy, calorimetry, thermogravimetry, and rheology. The
polyhydroxyalkanoic acid synthase gene (phaC) sequence had 77% identity with the phaC gene of P. denitrificans PD1222 strain. Additionally, the translated sequence showed an 86% similarity with the amino acid sequence of the phaC gene N-terminal portion of the P. denitrificans PD1222 strain. Our phaC sequence was closely related to two phaC sequences that correspond to P. denitrificans; therefore, this is the first report of a sequence of phaC that codifies a poly-(3-hydroxyalkanoate) synthase class I, specifically a poly-beta-hydroxybutyrate polymerase from the
marine bacteria Paracoccus seriniphilus. The polymer PHA of E71 melts at 167.86°C (T
m), which corresponded to the fusion of the crystalline polymer and thermally degrades at 296.52°C, indicating that the biopolymer
has good thermal stability. Rheology showed that this polymer behaves as a nonNewtonian fluid. All these characteristics suggest
that the E71 strain produces a PHA that corresponds to the crystalline thermoplastic polymer PHB type. 相似文献
665.
Julio Villatoro-Hernandez Maria J Loera-Arias Anali Gamez-Escobedo Moises Franco-Molina Jorge G Gomez-Gutierrez Humberto Rodriguez-Rocha Yolanda Gutierrez-Puente Odila Saucedo-Cardenas Jesus Valdes-Flores Roberto Montes-de-Oca-Luna 《Microbial cell factories》2008,7(1):22
Background
Chemokines are a large group of chemotactic cytokines that regulate and direct migration of leukocytes, activate inflammatory responses, and are involved in many other functions including regulation of tumor development. Interferon-gamma inducible-protein-10 (IP-10) is a member of the C-X-C subfamily of the chemokine family of cytokines. IP-10 specifically chemoattracts activated T lymphocytes, monocytes, and NK cells. IP-10 has been described also as a modulator of other antitumor cytokines. These properties make IP-10 a novel therapeutic molecule for the treatment of chronic and infectious diseases. Currently there are no suitable live biological systems to produce and secrete IP-10. Lactococcus lactis has been well-characterized over the years as a safe microorganism to produce heterologous proteins and to be used as a safe, live vaccine to deliver antigens and cytokines of interest. Here we report a recombinant strain of L. lactis genetically modified to produce and secrete biologically active IP-10. 相似文献666.
Julio Bohrquez Danielle Calenti Emilio García‐Robledo Sokratis Papaspyrou Juan Luis Jimenez‐Arias Eddy Humberto Gmez‐Ramírez Alfonso Corzo 《Journal of phycology》2019,55(3):625-636
Primary production of microphytobenthos (MPB) contributes significantly to the total production in shallow coastal environments. MPB is a diverse community in which diatoms are usually the main microalgal group. Diatoms require N, P, and other nutrients as with other autotrophs, but in addition require silicate to create their outer cell wall. Therefore, dissolved silica (DSi) might be a potential limiting factor for benthic primary production in areas with reduced freshwater input. To test this hypothesis, a microcosm experiment was conducted using intact sediment cores collected from an intertidal mudflat in the Bay of Cádiz and supplied with increasing concentrations of DSi (0, 5, 10, 25, and 45 μmol · L?1). After 7 d of enrichment, we determined chlorophyll a and c (Chl a, c) contents, metabolic rates (Net [Pn] and Areal Gross [PgA] Production and Light [RL] and Dark [RD] Respiration), as well as fluxes of inorganic nutrients across the sediment‐water interface. Chl a and c contents increased significantly with respect to the initial conditions but no differences between treatments were found. Both Pn and PgA showed a saturating‐like pattern with silicate concentration, reaching maximum rates at a DSi concentration of 45 μmol · L?1. The addition of DSi also resulted in an increase of DSi and ammonium uptake by the sediment, which was significantly higher in light than in darkness. Our results clearly show that water column DSi concentrations have a direct impact on benthic primary production, also controlling other related processes such as inorganic nutrient fluxes. 相似文献
667.
668.
Diel variations of temperature, O2 and CO2 profiles were measured in two oligotrophic shallow lakes situated next to a large preserved area of the Atlantic Tropical
Forest (Brazil) in three sampling periods between the rainy season (spring and summer) and the dry winter of 2005. Our hypothesis
was that lakes with high dissolved organic carbon (DOC) concentrations by terrestrial inputs might show the persistence of
CO2 emissions to the atmosphere over the course of the year, despite changes in the water stratification pattern. In both lakes,
temperature, O2 and CO2 showed a significant stratification in the beginning and end of the rainy season, and destratification in the dry winter.
The beginning of the rainy season showed DOC concentrations and CO2 saturation that were significantly higher, but a persistence of CO2 emissions to the atmosphere was observed in all sampling periods. In conclusion, tropical shallow oligotrophic lakes might
show events of thermal, O2 or CO2 stratification and destratification coupled to persistence of CO2 outgassing, possibly subsiding by terrestrial influence. 相似文献
669.
Jahir Antonio Barajas-Ramírez Angel Humberto Cabrera-Ramírez Victoria Guadalupe Aguilar-Raymundo 《化学与生物多样性》2023,20(1):e202200834
In Mexico, plants are commonly used to alleviate various ailments, including controlling some chronic degenerative diseases through the regular consumption of decoctions, infusions, and teas. However, there is little scientific evidence consolidating traditional medicine within health systems. Therefore, this work determined the phytochemical profile of the most used plants to treat various ailments (Cedro rojo, Cancerina, Ortiguilla, Hierba de la golondrina, Hierba de arlomo) and their general consumption as infusions. Aqueous and ethanolic extracts were generated, while the phytochemical compound content in the extracts obtained was quantified. The results indicate that the ethanolic extracts showed the highest phenolic compound and tannin content, with the highest contents for Cedro rojo (831.04 mg L−1) and Cancerina (864.80 mg L−1). The antioxidant activity was also determined, and a significant difference was observed (p<0.05). The extracts with the highest antioxidant capacity were the ethanolic extracts ranging from 250 to 907 μMET mL−1, while the aqueous extracts ranged from 112 to 390 μMET mL−1. The compounds identified by high-performance liquid chromatography characterization on the aqueous extracts highlighted the presence of chlorogenic acid>cinnamic acid>quercetin. In ethanolic extracts, the presence of chlorogenic acid>cinnamic acid>quercetin>gallic acid>ferulic acid>coumaric acid was highlighted. The correlation between bioactive compounds, type of extract, and antioxidant activity suggests a significant affinity of these phytochemical compounds for the ethanol solvent. The results indicate that these plants are good sources of antioxidant phenolics and can be incorporated for use as functional beverages. However, more studies are needed to corroborate their beneficial effect. 相似文献
670.
Rodrigo Franco Sumin Li Humberto Rodriguez-Rocha Michaela Burns Mihalis I. Panayiotidis 《Chemico-biological interactions》2010,188(2):289-300
Pesticides are widely used in agricultural and other settings, resulting in continued human exposure. Pesticide toxicity has been clearly demonstrated to alter a variety of neurological functions. Particularly, there is strong evidence suggesting that pesticide exposure predisposes to neurodegenerative diseases. Epidemiological data have suggested a relationship between pesticide exposure and brain neurodegeneration. However, an increasing debate has aroused regarding this issue. Paraquat is a highly toxic quaternary nitrogen herbicide which has been largely studied as a model for Parkinson's disease providing valuable insight into the molecular mechanisms involved in the toxic effects of pesticides and their role in the progression of neurodegenerative diseases. In this work, we review the molecular mechanisms involved in the neurotoxic action of pesticides, with emphasis on the mechanisms associated with the induction of neuronal cell death by paraquat as a model for Parkinsonian neurodegeneration. 相似文献