A soluble inorganic pyrophosphatase from the cattle tick Rhipicephalus microplus capable of hydrolysing polyphosphates.

Polyphosphates have been found in all cell types examined to date and play diverse roles depending on the cell type. In eukaryotic organisms, polyphosphates have been investigated mainly in mammalian cells, and only a few studies have addressed arthropods. Pyrophosphatases have been shown to regulate polyphosphate metabolism. However, these studies were restricted to trypanosomatids. Here we focus on the tick Rhipicephalus microplus, a haematophagous ectoparasite that is highly harmful to cattle. We produced a recombinant R. microplus pyrophosphatase (rRmPPase) with the aim of investigating its kinetic parameters using polyphosphates as substrate. Molecular docking assays of RmPPase with polyphosphates were also carried out. The kinetic and Hill coefficient parameters indicated that rRmPPase has a greater affinity, higher catalytic efficiency and increased cooperativity for sodium phosphate glass type 15 (polyP15 ) than for sodium tripolyphosphate (polyP3 ). Through molecular docking, we found that polyP3 binds close to the Mg2+ atoms in the catalytic region of the protein, participating in their coordination network, whereas polyP15 interactions involve negatively charged phosphate groups and basic amino acid residues, such as Lys56, Arg58 and Lys193; polyP15 has a more favourable theoretical binding affinity than polyP3 , thus supporting the kinetic data. This study shows, for the first time in arthropods, a pyrophosphatase with polyphosphatase activity, suggesting its participation in polyphosphate metabolism.

Colostrum yield and litter performance in multiparous sows subjected to farrowing induction.

The consumption of colostrum at a low level can compromise the survival and growth of piglets. Therefore, this study aimed to evaluate the effect of farrowing induction on colostrum yield, IgG concentration and the survival and performance of piglets until the weaning. Sows of parity 3 to 7 were assigned into two groups: Control (n = 48), sows with spontaneous farrowing; and induction (n = 48), sows induced to farrow on day 114 of gestation with a PGF2 analogue. Colostrum and blood samples were collected from the sows, at farrowing and 24 hr later. Blood samples from the piglets were collected at 24 hr after birth. The performance of the piglets was evaluated in a subsample of 28 litters from each group. All piglets were weighed at 7, 14 and 20 days of age. The farrowing length, the number of piglets born alive, stillborn piglets, weight at birth, litter weight at birth and colostrum yield were not significantly affected (p > .05) by farrowing induction. There was no difference between the groups (p > .05) in the percentage of sows with obstetric interventions. Serum IgG concentration, in both sows and piglets, and colostrum IgG concentration were similar between the groups (p > .05). Furthermore, survival rate, piglet weight and litter weight at 7, 14 and 20 days of age were also similar between the groups (p > .05). Therefore, it can be concluded that the farrowing induction performed on day 114 of gestation does not affect the colostrum yield, the IgG concentration in colostrum and serum of piglets, and the litter performance until the weaning.

Effect of birth weight and colostrum intake on mortality and performance of piglets after cross-fostering in sows of different parities.

The objective of this study was to evaluate the effect of colostrum intake on mortality and growth performance of piglets until 42 days of age, taking into account the birth weight, and parity order of sows. Colostrum intake from birth to 24h after birth was estimated in 300 piglets each from primiparous and multiparous sows. The piglets were cross-fostered in 25 primiparous and 25 multiparous sows at 25.9±0.09 h after farrowing. The concentration of serum immunoglobulin G (IgG) was determined in the sows after the end of farrowing and in the piglets before cross-fostering (24h after farrowing), at 10 and 20 days of age. For high birth weight piglets (HBW - >1.3-1.7 kg) the probability of death was low regardless of their colostrum intake. Intermediate birth weight (IBW - >1.2-1.3 kg) and low birth weight (LBW - 1.1-1.2 kg) piglets had the same probability of death compared to HBW piglets, when colostrum intake reached 200 and 250 g, respectively. The probability of low performance (<9.5 kg) was lower in HBW than in LBW and IBW piglets, regardless of colostrum intake. HBW piglets had higher weight at 14, 20, 28 and 42 days of age (P<0.05) than LBW piglets, and higher weight than IBW piglets at 28 and 42 days. Colostrum intake >250 g increased (P<0.05) the weight of piglets at 28 and 42 days of age, regardless of their birth weight. Piglets from primiparous biological dams consumed less colostrum (P<0.003) than piglets from multiparous dams, but their serum IgG concentrations at 24h after birth and their performance were similar (P>0.05). Piglets suckled by primiparous foster sows showed lower weight (P<0.05) at 20, 28 and 42 days than piglets suckled by multiparous sows. Piglets that died before 42 days of age had lower (P<0.05) birth weight, colostrum intake and serum IgG at 24 h after birth compared to surviving piglets, and lower values were also observed in piglets with low performance compared to high (>9.5 kg) performance piglets. There were no differences in serum IgG concentrations at 10 and 20 days of age (P>0.05) between high and low performance piglets. In conclusion, both colostrum intake and birth weight are important for survival and growth of suckling piglets. LBW and IBW piglets are more dependent on colostrum intake than HBW piglets to assure higher survival and better development up to 42 days of age. Piglets suckled by multiparous sows have better development than those suckled by primiparous sows.

Binding and storage of heme by vitellin from the cattle tick, Boophilus microplus.

We have previously shown (, Curr. Biol. 9, 703-706) that the cattle tick Boophilus microplus does not synthesize heme, relying solely on the recovery of the heme from the diet to make all its hemeproteins. Here we present evidence that Vitellin (VN(1)), the main tick yolk protein, is a reservoir of heme for embryo development. VN was isolated from eggs at different days throughout embryogenesis. Immediately after oviposition, Boophilus VN contains approximately one mol of heme/mol of protein. During embryo development about one third of egg VN is degraded. The remaining VN molecules bind part of the heme released. These results suggest that VN functions as a heme reservoir, binding any free heme that exceeds the amount needed for development. In vitro measurement of the binding of heme to VN showed that each VN molecule binds up to 31 heme molecules. The association of heme with VN strongly inhibits heme-induced lipid peroxidation, suggesting that binding of heme is an important antioxidant mechanism to protect embryo cells from oxidative damage. This mechanism allows this hematophagous arthropod to safely store heme obtained from a blood meal inside their eggs for future use. Taken together our data suggest that, besides its known roles, VN also plays additional functions as a heme deposit and an antioxidant protective molecule.