Lipoproteins of spider: Structure and function

GARCIA FERNANDO; ALDANA LAINO; CUNNINGHAM MONICA

Spiders: Morphology, Behavior and Geographic Distribution

NOVA SCIENCE PUBLISHERS

Año: 2012;

It is well known that the class Arachnida is one of the arthropod groups with major diversity in the world. There are around 100 families belonging to the Order Araneae; over 42,000 species from different geographical areas have been described. In the last few years biochemical/physiological studies in some species of spiders: Polybetes pythagoricus, Latrodectus mirabilis, Eurypelma californicum, Cupiennius salei, Nephila inaurata among others have significantly increased. Many of them are based on the venom characterization, but only a few of them are related to basic molecules such as lipids, proteins or carbohydrates.Lipids are transported from the tissue of origin to those tissues where they are either stored or metabolized. In an aqueous environment as the hemolymph they must be associated to proteins, forming lipoproteins which may be more complex generating the so-called glycolipoproteins,Within the class Arachnida, different lipoproteins were identified and characterized in the orders Araneae, Acarai, Scorpionida and Solpugida. In only three species of spiders, Polybetes pythagoricus and Latrodectus mirabilis (Suborder Araneomorphae) and Euryplema californicum (Suborder Mygalomorphae), lipoproteins of different density were purified and studied. P. pythagoricus belongs to the Sparasside family, and it is only found in South America, while L. mirabilis belongs to the Theridiidae family and is distributed in the center and south of Argentina and Uruguay. E. californicum belongs to the Theraphosidae family that is present in the American continent, mainly in North America. Lipoproteins of high density ranging from 1.07 to 1.14 g/ml have been detected as the major circulating lipoproteins in these species. Concerning the lipid composition of Araneomorphae, the major lipids are phosphatidylcholine, free fatty acids and triacylglycerides (being this one the major energetic lipid). As to Myghalomorphae E. californicum, this lipoprotein of high density named lipophorin as in insects, mainly contains phospholipids and diacylglycerol (the major energetic lipid).  Another high density lipoprotein named HDL2 is found in P. pythagoricus and L. mirabilis, while P. pythagoricus and E. californicum have a third lipoprotein of very high density (VHDL) in hemolymph. It is important to remark that the hemocyanin in P. pythagoricus and L. mirabilis, in addition to its classical role as respiratory pigment, plays functions as apolipoprotein. Lately, P. pythagoricus has been used as a model in order to further study hemolymph lipoproteins (HDL1, HDL2 and VHDL). For the first time, egg glycolipoproteins of high and very high density (LV1 and LV2) which are responsible for the embryo nutrition, were identified in class Arachnida. Phospholipids are the major structural lipids. Oleic acid is the major component in both lipoproteins. These particles are spheroidal and their diameter ranges between 20 nm in LV1 and 27 nm in LV2.Recently, we have reported data on the primary, secondary and tertiary structure of VHDL by using spectroscopy and sequencing methods.Despite the fact that biochemical and physiological studies dealing with lipoproteins have increased, further studies are necessary to elucidate the dynamics of proteins and lipids in arachnids.