The role of selective breeding and biosecurity in the prevention of disease in penaeid shrimp aquaculture

About 3.5 million metric tons of farmed shrimp were produced globally in 2009 with an estimated value greater than USD$14.6 billion. Despite the economic importance of farmed shrimp, the global shrimp farming industry continues to be plagued by disease. There are a number of strategies a shrimp farmer can employ to mitigate crop loss from disease, including the use of Specific Pathogen Free (SPF), selectively bred shrimp and the adoption of on-farm biosecurity practices. Selective breeding for disease resistance began in the mid 1990s in response to outbreaks of Taura syndrome, caused by Taura syndrome virus (TSV), which devastated populations of farmed shrimp (Litopenaeus vannamei) throughout the Americas. Breeding programs designed to enhance TSV survival have generated valuable information about the quantitative genetics of disease resistance in shrimp and have produced shrimp families which exhibit high survival after TSV exposure. The commercial availability of these selected shrimp has benefitted the shrimp farming industry and TSV is no longer considered a major threat in many shrimp farming regions. Although selective breeding has been valuable in combating TSV, this approach has not been effective for other viral pathogens and selective breeding may not be the most effective strategy for the long-term viability of the industry. Cost-effective, on-farm biosecurity protocols can be more practical and less expensive than breeding programs designed to enhance disease resistance. Of particular importance is the use of SPF shrimp stocked in biosecure environments where physical barriers are in place to mitigate the introduction and spread of virulent pathogens.     

The effect of prostaglandins A2,E1,E2,15 methyl E2, 16, 16 dimethyl E2 and F2α on erythropoiesis

Prostaglandins A₂, E₁, E₂, methylated E₂s and F₂α affected erythropoiesis and/or erythropoietin (Ep) production. This action is indicated in the exhypoxic, polycythemic mouse where radioiron incorporations into RBC increased after administration of these compounds. The kidney and liver have been indicated through previous studies, to actively participate in Ep production. By the removal of one of these active sites in a murine system treated with prostaglandins it is shown that a response is reflected in Ep levels. Interference of the action of prostaglandins (PG) is altered by the removal of one of these target sites of Ep production. The erythropoietic responses elicited by PGA₂, E₁, and perhaps the methylated PGE₂s act through the liver whereas PGE₂ may operate through a renal pathway for its response. PGF_2α reveals no effect on erythropoietic activity and is no different than that observed for vehicle-treated controls. The prostaglandins tested appear to act primarily through the kidney or liver but the possibility exists that some yet undetermined organ site may also be involved.     

CAPABILITY OF TUBULIN AND MICROTUBULES TO INCORPORATE AND TO RELEASE TYROSINE AND PHENYLALANINE AND THE EFFECT OF THE INCORPORATION OF THESE AMINO ACIDS ON TUBULIN ASSEMBLY

Abstract— Incorporation of [¹⁴C]tyrosine into the C-terminal position of α-tubulin of rat brain cytosol was 10-fold higher for non-assembled than for assembled tubulin. The incorporation into tubulin from disassembled microtubules was higher than into non-assembled tubulin; therefore, the low incorporation into microtubules was not due to a lower acceptor capacity of their tubulin constituent.
[¹⁴C]Tyrosine was released from assembled and non-assembled [¹⁴C]tyrosinated tubulin by the action of an endogenous carboxypeptidase. Release from non-assembled tubulin was shown by incubating a tubulinyl-[¹⁴C]tyrosine preparation in the presence of CaCl₂ at a concentration that abolished microtubule formation. Release from microtubules was inferred from the observation that the percentages of [¹⁴C]tyrosine released and the decrease of the specific radioactivity of the recovered microtubules were practically identical and did not change after a 10-fold dilution of the incubated microtubules.
[³H]Phenylalanine was released from a preparation of tubulinyl-[³H]phenylalanine also by an enzymatic activity.
The capacity of a tubulin preparation to incorporate tyrosine was increased 43% by pre-treatment with endogenous carboxypeptidase.
Tubulin tyrosinated in vitro was assembled to the same extent as native tubulin. After a mixture of tubulinyl-[¹⁴C]tyrosine and tubulinyl-[³H]phenylalanine was partially assembled, the ratio of ¹⁴C/³H found in the microtubules was the same as in the non-assembled tubulin fraction.     

Isolation and characterization of a potato cDNA corresponding to a 1-aminocyclopropane-1-carboxylate (ACC) oxidase gene differentially activated by stress

1-Aminocyclopropane-1-carboxylate (ACC) oxidase enzyme catalyses the final step in ethylene biosynthesis, converting 1-aminocyclopropane-1-carboxylic acid to ethylene. A cDNA clone encoding an ACC oxidase, ST-ACO3, was isolated from potato (Solanum tuberosum L.) by differential screening of a Fusarium eumartii infected-tuber cDNA library. The deduced amino acid sequence exhibited similarity to other ACC oxidase proteins from several plants species. Northern blot analysis revealed that the ST-ACO3 mRNA level increased in potato tubers upon inoculation with F. eumartii, as well as after treatment with salicylic acid and indole-3-acetic acid, suggesting a cross-talk between different signalling pathways involved in the defence response of potato tubers against F. eumartii attack.     

Tubulin carboxypeptidase assay based on the action of the enzyme on [14C]tyrosinated tubulin bound to nitrocellulose membrane

We have developed a method for the determination of tubulin carboxypeptidase activity which is based on the action of the enzyme on the substrate, [14C]tyrosinated tubulin, previously adsorbed on nitrocellulose membrane. In addition to being two to three times more sensitive than previous carboxypeptidase assays, this method allows the determination of dilute enzyme preparations even containing high salt (inhibitory) concentrations. This is a valuable property specially under circumstances in which numerous high salt-containing fractions with scarce activity should be analyzed (for example after certain chromatographic stages during enzyme purification). Our method is simpler, less time-consuming, and suitable for multiple, simultaneous determinations and the substrate bound to nitrocellulose can be stored for several months without significant alteration of its properties. Peptidases other than tubulin carboxypeptidase can act on [14C]tyrosinated tubulin bound to nitrocellulose, solubilizing radioactive compounds, suggesting the eventual applicability of this method to assay proteases in general. Other features and advantages of the assay as well as its limitations are discussed.     

Tubulin–Na+ ,K +-ATPase interaction: Involvement in enzymatic regulation and cellular function

A new function for tubulin was described by our laboratory: acetylated tubulin forms a complex with Na⁺,K ⁺-ATPase (NKA) and inhibits its activity. This process was shown to be a regulatory factor of physiological importance in cultured cells, human erythrocytes, and several rat tissues. Formation of the acetylated tubulin–NKA complex is reversible. We demonstrated that in cultured cells, high concentrations of glucose induce translocation of acetylated tubulin from cytoplasm to plasma membrane with a consequent inhibition of NKA activity. This effect is reversed by adding glutamate, which is coctransported to the cell with Na ⁺. Another posttranslational modification of tubulin, detyrosinated tubulin, is also involved in the regulation of NKA activity: it enhances the NKA inhibition induced by acetylated tubulin. Manipulation of the content of these modifications of tubulin could work as a new strategy to maintain homeostasis of Na ⁺ and K ⁺, and to regulate a variety of functions in which NKA is involved, such as osmotic fragility and deformability of human erythrocytes. The results summarized in this review show that the interaction between tubulin and NKA plays an important role in cellular physiology, both in the regulation of Na ⁺/K ⁺ homeostasis and in the rheological properties of the cells, which is mechanically different from other roles reported up to now.     

Parathyroid hormone-related protein is a hypertrophy factor for human mesangial cells: Implications for diabetic nephropathy

Hypertrophy of human mesangial cells (HMC) is among the earliest characteristics in patients with diabetic nephropathy (DN). Recently, we observed the upregulation of parathyroid hormone (PTH)-related protein (PTHrP) in experimental DN, associated with renal hypertrophy. Herein, we first examined whether PTHrP was overexpressed in human DN, and next assessed the putative role of this protein on high glucose (HG)-induced HMC hypertrophy. As previously found in mice, kidneys from diabetic patients showed an increased tubular and glomerular immunostaining for PTHrP. In HMC, HG medium increased PTHrP protein expression associated with the development of hypertrophy as assessed by cell protein content. This effect was also induced by PTHrP(1-36). HG and PTHrP(1-36)-induced hypertrophy were associated with an increase in cyclin D1 and p27Kip1 protein expression, a decreased cyclin E expression, and the prevention of cyclin E/cdk2 complex activation. Both PTHrP neutralizing antiserum (α-PTHrP) and the PTH/PTHrP receptor antagonist (JB4250) were able to abolish HG induction of hypertrophy, the aforementioned changes in cell cycle proteins, and also TGF-β1 up-regulation. Moreover, the capability of both HG and PTHrP(1-36) to induce HMC hypertrophy was abolished by α-TGFβ1. These data show for the first time that PTHrP is upregulated in the kidney of patients with DN. Our findings also demonstrate that PTHrP acts as an important mediator of HG-induced HMC hypertrophy by modulating cell cycle regulatory proteins and TGF-β1.     

Evaluation of a Phylogenetic Marker Based on Genomic Segment B of Infectious Bursal Disease Virus: Facilitating a Feasible Incorporation of this Segment to the Molecular Epidemiology Studies for this Viral Agent

BackgroundInfectious bursal disease (IBD) is a highly contagious and acute viral disease, which has caused high mortality rates in birds and considerable economic losses in different parts of the world for more than two decades and it still represents a considerable threat to poultry. The current study was designed to rigorously measure the reliability of a phylogenetic marker included into segment B. This marker can facilitate molecular epidemiology studies, incorporating this segment of the viral genome, to better explain the links between emergence, spreading and maintenance of the very virulent IBD virus (vvIBDV) strains worldwide.Conclusions/SignificanceThis study contributes to a better understanding of the emergence of vvIBDV strains, describing molecular epidemiology of IBDV using the state-of-the-art methodology concerning phylogenetic reconstruction. This study also revealed the presence of a novel natural reassorted strain as possible manifest of change in the genetic structure and stability of the vvIBDV strains. Therefore, it highlights the need to obtain information about both genome segments of IBDV for molecular epidemiology studies.     

Zygia nubigena sp. nov. (Leguminosae–Mimosoideae) from a submontane cloud forest in western Ecuador

A new species, Zygia nubigena Ståhl, L. Rico & G. P. Lewis (Leguminosae–Mimosoideae), is described from western Ecuador. It is characterized by large and very thick‐walled fruits with coarsely alveolate‐reticulate surfaces, spicate inflorescences, one (less common) or two pairs of pinnae per leaf and 4 or 5 pairs of petiolulate leaflets per pinna. In leaf features, Z. nubigena is similar to Z. steyermarkii (Schery) Barneby & J. W. Grimes from montane forest in southern Ecuador, but differs by having somewhat smaller flowers borne in long, many‐flowered racemes (not 25–30‐flowered capitulae). The fruits of Z. nubigena resemble those of Z. rhytidocarpa L. Rico (Honduras, Guatemala) and Z. megistocarpa (Barbosa) L. Rico (northern Peru), but Z. nubigena differs from both in vegetative and floral characters.     

In Vivo and In Vitro Effects of Some Plant Hormones on Rat Erythrocyte Carbonic Anhydrase and Glucose-6-Phosphate Dehydrogenase Activities

The present study was undertaken to determine in vivo and in vitro effects of some plant growth regulators on rat erythrocyte carbonic anhydrase (CA) and glucose-6-phosphate dehydrogenase (G6PD) activities. Both in vivo and in vitro, spermidine and kinetin did not affect enzymatic activities of CA and G6PD, whereas putrescine decreased these activities, and abscisic acid increased them. Since plants use such growth regulators, their effects should be considered on mammals consuming them since they may possess important biological effects.