Scolopendra Cingulata Classification Essay

Classification


     One would hope that there are only a handful of different species of these creepy crawlers, but in fact there are over 700 species in the Scolopendra genus alone (Simaiakis et al. 1829). This page will show you where the Scolopendra cingulata falls within the phylogenetic tree of life.

Domain: Eukarya

     Of the three major domains of life, the Scolopendra cingulata is a Eukaryote which means it membrane bound organelles as well as the presence of a nucleus (Animal Diversity Web, 2014).

Kingdom: Animalia

     Organisms under this kingdom are multicellular, heterotrophic and obtain nutrients by ingestion.  These organisms at some point in their life have the power to move at their own will (Animal Diversity Web, 2014).

Phylum: Arthropoda

     Animals of this nature have a hard exoskeleton to provide them with protection, segmented bodies giving them a larger range of motion and better turning ablility, and jointed appendages to help with movement as well (Animal Diversity Web, 2014).

Class: Chilopoda

     This is where all species of centipedes fall under.  These organisms have elongated, multi-segmented bodies with many different sets of legs.  Most centipedes are under 20 centimeters in length excluding some species that inhabit tropic regions (Dioguardi, 2005).

Order: Scolopendromorpha

     This order contains all the larger species of centipedes.  These cenitpedes grow to around 20 centimeters with some reaching lengths even greater than that (Animal Diversity Web, 2014).

Family: Scolopendridae

     This family includes the larger centipedes that have venom used as defense and as a means of killing their prey (Animal Diversity Web, 2014).

Species: Scolopendra cingulata

     The Megarian banded centipede live in and around the Mediterranean sea.  They have alternating black and yellow bands on their segmented bodies and usually reach lengths of about 15 centimeters.  They use venom to take down and kill their prey and deter preditors from choosing them as their next meal (Animal Diversity Web, 2014).

 

 

 

 

 

 

 

 

 

 

 

 

This is a image of a phylogenetic tree of the 3 major domains of life.  The red circle shows where the S. cingulata is among the three domains. 

 

 

 

 

 

 

 

 

 

 

 

This image is of the Order Scolopendromorpha showing all the families within.  The red circle shows that the S. cingulata is in the Scolopendrinae family.

 

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 Andre McMillion and Jaelen Yach of the University of Wisconsin - La Crosse. Bio 203 - Spring 2014 


1. Introduction

Class Chilopoda, or centipedes, represents one of the four major myriapod lineages (Arthropoda; Myriapoda). They are present on every continent except Antarctica and are an important group of terrestrial predatory arthropods. There are about 3500 species worldwide within five extant orders: Scutigeromorpha (“house centipedes”), Lithobiomorpha (“stone centipedes”), Craterostigmomorpha (only two congeneric species), Geophilomorpha (“earth centipedes”), and Scolopendromorpha (the largest, most commonly media-documented centipedes) (Figure 1). Several morphological characters unite the members of Chilopoda, of which the most obvious is the modification of the first pair of walking legs into venomous appendages known as poison claws, toxicognaths, maxillipeds, or more correctly forcipules [1]. These are used to capture a wide variety of prey, including insects, spiders, crustaceans, snails, amphibians, reptiles, and even mammals; scutigeromorphs feed primarily by ambushing and chasing down prey, while the other orders seem to rely on opportunistic encounters [2].

Figure 1. Phylogenetic relationship between the five extant centipede orders according to the Amalpighiata hypothesis. Times since divergence are based on Fernández et al. [3].

Figure 1. Phylogenetic relationship between the five extant centipede orders according to the Amalpighiata hypothesis. Times since divergence are based on Fernández et al. [3].

Centipedes are thought to have split from the remaining myriapods at least 460 million years ago (mya) [3]. The oldest recognizable order from the fossil record is Scutigeromorpha, of which fossilized legs belonging to a Crussolum sp. have been found from the late Silurian almost 420 mya [4]. The earliest fossilized forcipules, from the early Devonian about 400 mya, belonged to the same genus Crussolum and are similar to those of the modern scutigeromorph Scutigera coleoptrata [5]. The centipede venom apparatus had evolved well before this, however, since the basal split within Chilopoda between Notostigmophora (Scutigeromorpha) and Pleurostigmophora (remaining orders) occurred approximately 430 mya [3]. The centipede venom apparatus thus represents one of the oldest extant venom systems known among terrestrial animals, probably even preceding evolution of the venom systems of scorpions and spiders [6,7].

Unlike scorpions and spiders, centipede venoms have attracted relatively little attention, partly due to their cryptic nature and generally small body size and in part due to their lack of medical importance. Venom extraction in centipedes can be time-consuming, and venom yields are typically very low; even relatively large centipedes such as Scolopendra polymorpha (~10 cm) and S. subspinipes (~15 cm) yield an average of 1.1 and 5 µL of venom, respectively, when milked using electrostimulation [8]. However, recent advances in the analytical methods employed in toxinological studies have enabled broader study and appreciation of venomous animal diversity, including more challenging taxa such as centipedes [9]. Consequently, a number of substantial discoveries and advances in the fields of centipede toxinology and centipede venom-based biodiscovery have been made since the first review on centipede venoms in 2011 [2]. This review therefore aims to summarize current knowledge on centipede venoms and provide an updated nomenclatorial framework for organisation and naming of centipede toxins.

2. Venom Apparatus

Centipede forcipules are shaped like a set of piercing forceps, each consisting of four or five segments: a large trochanteroprefemur, two short segments (femur and tibia), and an apical claw. While the apical claw is made up of two segments in Scutigeromorpha, the tarsus and ungulum, these are fused in all other centipedes and hence referred to as the tarsungulum [1]. The outer surface of each claw contains at least three types of sensilla ceoloconica-type chemoreceptors, which may be used for tasting prey, stimulating the secretion of venom by sensing penetration by the apical claw, or both [10,11]. Interestingly, the evolutionary progression from walking appendages to highly specialised venom delivery systems can be traced by comparison of forcipules from extant centipede orders [12]. This reveals a gradual transformation of the plesiomorphic, slender forcipules found in Scutigeromorpha to the highly modified forcipules found in Geophilomorpha.

The venom glands of most centipedes are pear-shaped, with the exception of scolopendrid centipedes where they are elongated and kidney-shaped. The proximal segments of the forcipules usually contain the venom gland, which line the cuticle along the outer curvature of the appendage and terminate near the base of the forcipule. There are, however, some interesting exceptions. Within the genus Cryptops (Cryptopidae, Scolopendromorpha), for example, glands can vary from pear-shaped organs occupying a significant volume of the forcipule to just a few glandular cells [13,14,15]. Gland size also varies within the Scolopendridae, such as in Asanada socotrana and Arthrorhabdus formosus where they extend into the posterior part of the forcipular coxosternite [16]. The most extreme variation, however, can be found among geophilomorph centipedes. In Henia vesuviana (Dignathodontidae), the venom glands are located in the trunk, between the 12th and 18th segments, while in Aphilodon angustatus (Aphilodontidae) these are placed even further back into the trunk, between the 15th and 23rd segments [2]. In the latter case, each gland is placed in front of the other and even occupies most of the volume of the three segments it spans [17].

While the forcipules are modified walking appendages, the venom gland is thought to have evolved through invagination of the cuticle and weaponization of the cuticular dermal glands [2,18,19,20]. This is evident from the chitinous duct, and the observation that the venom gland is actually a composite glandular epidermis composed of discrete sub-glands, or secretory units. Each secretory unit includes a distal and a proximal canal cell, one or more secretory cells, and an intermediate cell that line an extracellular storage space. These secretory units are individually connected to the lumen through a one-way valve formed by the distal canal cell that penetrates the chitinous duct though a pore. Venom is then expelled from the porous region of the duct, known as the calyx, and through the distal non-porous duct that terminates as a pore (“meatus”) located on the outer curvature near the tip of each claw [1,20].

3. Molecular and Pharmacological Diversity

Until very recently, the toxin arsenals of centipedes remained almost completely unstudied [2]. A few non-peptidic venom components had been described, including 5-hydroxytryptamine (5-HT or serotonin) and histamine [21,22]. However, the large majority of proteinaceous venom components remained mostly undescribed. The novelty of centipede venoms was apparent from early studies of their cardiotoxic and neurotoxic properties, where the responsible venom components were identified as being of surprisingly high molecular weight [23,24]. The prevalence of hitherto undescribed toxin types was also confirmed by N-terminal sequencing; of 24 proteins from two species of Scolopendra only two CAP [CRiSP (cysteine rich proteins), Allergen (Ag-5), and Pathogenesis-related (PR-1)] proteins were identified [25]. Improvements in sequencing and mass spectrometry platforms have recently enabled more detailed insights into the composition, evolution, and putative mode of action of centipede venoms. Although the taxonomical range of species examined is currently limited to members of the scolopendromorph family Scolopendridae as well as a single scutigeromorph species, these more recent studies confirm that centipede venoms are a rich and diverse source of novel toxins and structural scaffolds (Table 1, Figure 2).

3.1. Molecular and Pharmacological Diversity—Enzymes

Mohamed and co-workers [21] were the first to show enzymatic activity in centipede venom, namely phosphatase and esterase activity from the venom of Scolopendra morsitans. Since then, 11 types of enzymes have been described from the venoms of Scolopendromorpha and Scutigeromorpha. Some of these have been shown by proteomic analyses to be abundant venom components, indicating that enzymes generally form an important component of centipede venoms [2,26,27,28,29]. Although most centipedes have well developed mandibles that are used for mastication of solid food prior to ingestion [30], the substantial enzymatic component of their venom suggest that it may contribute to extra-oral digestion of prey.

3.1.1. Metalloproteases

Both activity- and sequence-based investigations have revealed that metalloproteases are important components of centipede venoms [27,29]. Transcriptomic and proteomic analyses of the venom proteome of Thereuopodalongicornis (Scutigeromorpha, Scutigeridae) revealed that astacin-like metalloendoproteases (MEROPS family M12, subfamily A) accounted for ~10% of venom proteins identified [29]. Similarly, analysis of venom by 2D PAGE revealed that proteins with weak sequence homology to blastula protease 10, an M12A member from sea urchin (UniProt: P42674, E-value 0.001), were abundant in scolopendrid species included in the same study. This suggests that metalloproteases in scolopendrid venoms could be derived members of the M12A subfamily, although proteolytic activity should be verified to confirm this. While no putative metalloproteases were reported from the venoms of Scolopendra viridis or Scolopendra subspinipes dehaani [26,31], this may be due to the limitations of the analytical approaches taken. For example, a search against the full set of published centipede-venom protein sequences reveals an EST (NCBI accession number JZ574148) that is highly similar to members of the scolopendrid putative M12A family (lowest E-value 3 × 10−72, to GASH01000091). Moreover, conducting the same search using the tryptic fragments from spot 2 from the 2D-PAGE of S. viridis (Table 7 in ref. [29]) reveals that this protein is actually a member of the same protein family. Hence, M12A proteases are probably a plesiotypic characteristic of centipede venoms.

Table 1. Centipede toxin families described to date. Where cysteine patterns are shown, “–” indicates unspecified loop length while “x” signifies a single residue.

Family nameTypeFunctionEarliest known recruitment
Enzymes
Protease M12AZinc metalloendopeptidase Unknown, potential spreading factorBasal
Protease S1Serine protease Potentially involved in activation of toxinsBasal
Protease S8Serine protease Potentially involved in activation of toxinsScolopendridae
γ-GTγ-GlutamyltransferasePlatelet aggregating activity, hemolytic to mouse and rabbit hemocytesBasal
ChitinaseGlycoside hydrolase family 18UnknownScolopendridae
Lysozyme CGlycoside hydrolase family 22Potential antimicrobial componentScolopendridae
HyaluronidaseGlycoside hydrolase family 56Degrades glycosaminoglycans, potentially facilitating the spread of venom componentsScolopendridae
GDHGlucose dehydrogenaseUnknownBasal
CarboxylesteraseType B carboxylesteraseUnknownBasal
CentiPADPeptidylarginine deiminaseVenom activity unknown; catalyses deamination of the guanidine group of arginine residues, potentially involved in post-translational modification of toxinsThereuopoda longicornis
ScolPLA2Phospholipase type A2Venom activity unknown; venom PLA2 can be myotoxic, inflammatory, and neurotoxicScolopendridae
Non-enzymatic proteins
β-PFTxβ-Pore-forming toxinPotentially cytotoxic via formation of polymeric pore structures in cell membranesBasal
CentiCAP1CAP protein UnknownBasal
CentiCAP2CAP proteinCaV channel antagonist (KC144967);
Trypsin inhibitor (KC144061)
Scolopendridae
CentiCAP3CAP proteinUnknownScolopendra morsitans
LDLA proteinLDLA-repeat domain containing proteinUnknownBasal
CystatinCystatinPotential protease inhibitorEthmostigmus rubripes
TransferrinTransferrinPotential antimicrobial componentBasal
DUF3472Protein containing a domain of unknown function type 3472UnknownScolopendridae
DUF1397Protein containing a domain of unknown function type 1397UnknownThereuopoda longicornis
Completely uncharacterized proteins
Family 1UnknownUnknownScolopendridae
Family 2 UnknownUnknownScolopendra morsitans
Family 3UnknownUnknownScolopendrinae
Family 4UnknownUnknownThereuopoda longicornis
Family 5Similar to hypothetical protein from Drosophila mojavensis (XP_002005038.1, BLAST E-value 4.42E-4)UnknownScolopendridae
Family 6UnknownUnknownScolopendridae
Family 7Similar to hypothetical protein from Chthionobacter flavus (EDY20616.1, BLAST E-value 6.13E-7) UnknownScolopendra morsitans
Family 8UnknownUnknownThereuopoda longicornis
Family 9UnknownUnknownScolopendra morsitans

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