Jamaica, brought together scientists and data from around the Caribbean region and made analysis of indices of extremes derived from daily weather observation in the region possible. The results of the analyses indicate that the percent of days having very warm maximum or minimum temperatures increased strongly since the late 1950s while the percent of days with very cold temperatures decreased. One measure of extreme precipitation shows an increase over this time period while the one analyzed measure of dry conditions, the maximum number of consecutive dry days, is decreasing. These changes generally agree with what is observed in many other parts of the world.

Two novel antimicrobial peptides have been identified and characterized from venom of the African scorpion Pandinus imperator. The peptides, designated pandinin 1 and 2, are α-helical polycationic peptides, with pandinin 1 belonging to the group of antibacterial peptides previously described from scorpions, frogs and insects, and pandinin 2 to the group of short magainin-type helical peptides from frogs. Both peptides demonstrated high antimicrobial activity against a range of Gram-positive bacteria (2.4–5.2μM), but were less active against Gram-negative bacteria (2.4–38.2μM), and only pandinin 2 affected the yeast Candida albicans. Pandinin 2 also demonstrated strong haemolytic activity (11.1–44.5μM) against sheep erythrocytes, in contrast with pandinin 1, which was not haemolytic. CD studies and a high-resolution structure of pandinin 2 determined by NMR, showed that the two peptides are both essentially helical, but differ in their overall structure. Pandinin 2 is composed of a single α-helix with a predominantly hydrophobic N-terminal sequence, whereas pandinin 1 consists of two distinct α-helices separated by a coil region of higher flexibility. This is the first report of magainin-type polycationic antimicrobial peptides in scorpion venom. Their presence brings new insights into the mode of action of scorpion venom and also opens new avenues for the discovery of novel antibiotic molecules from arthropod venoms.

Two novel antimicrobial peptides have been identified and characterized from venom of the African scorpion Pandinus imperator. The peptides, designated pandinin 1 and 2, are alpha-helical polycationic peptides, with pandinin 1 belonging to the group of antibacterial peptides previously described from scorpions, frogs and insects, and pandinin 2 to the group of short magainin-type helical peptides from frogs. Both peptides demonstrated high antimicrobial activity against a range of Gram-positive bacteria (2.4-5.2 microM), but were less active against Gram-negative bacteria (2.4-38.2 microM), and only pandinin 2 affected the yeast Candida albicans. Pandinin 2 also demonstrated strong haemolytic activity (11.1-44.5 microM) against sheep erythrocytes, in contrast with pandinin 1, which was not haemolytic. CD studies and a high-resolution structure of pandinin 2 determined by NMR, showed that the two peptides are both essentially helical, but differ in their overall structure. Pandinin 2 is composed of a single alpha-helix with a predominantly hydrophobic N-terminal sequence, whereas pandinin 1 consists of two distinct alpha-helices separated by a coil region of higher flexibility. This is the first report of magainin-type polycationic antimicrobial peptides in scorpion venom. Their presence brings new insights into the mode of action of scorpion venom and also opens new avenues for the discovery of novel antibiotic molecules from arthropod venoms.

Advances in NMR and mass spectrometry as well as in peptide biochemistry coupled to modern methods in electrophysiology have permitted the isolation and identification of numerous products from spider venoms, previously explored due to technical limitations. The chemical composition of spider venoms is diverse, ranging from low molecular weight organic compounds such as acylpolyamines to complex peptides. First, acylpolyamines (< 1000 Da) have an aromatic moiety linked to a hydrophilic lateral chain. They were characterized for the first time in spider venoms and are ligand-gated ion channel antagonists, which block mainly postsynaptic glutamate receptors in invertebrate and vertebrate nervous systems. Acylpolyamines represent the vast majority of organic components from the spider venom. Acylpolyamine analogues have proven to suppress hippocampal epileptic discharges. Moreover, acylpolyamines could suppress excitatory postsynaptic currents inducing Ca+ accumulation in neurons leading to protection against a brain ischemic insult. Second, short spider peptides (< 6000 Da) modulate ionic currents in Ca2+, Na+, or K+ voltage-gated ion channels. Such peptides may contain from three to four disulfide bridges. Some spider peptides act specifically to discriminate among Ca2+, Na+, or K+ ion channel subtypes. Their selective affinities for ion channel subfamilies are functional for mapping excitable cells. Furthermore, several of these peptides have proven to hyperpolarize peripheral neurons, which are associated with supplying sensation to the skin and skeletal muscles. Some spider N-type calcium ion channel blockers may be important for the treatment of chronic pain. A special group of spider peptides are the amphipathic and positively charged peptides. Their secondary structure is alpha-helical and they insert into the lipid cell membrane of eukaryotic or prokaryotic cells leading to the formation of pores and subsequently depolarizing the cell membrane. Acylpolyamines and peptides from spider venoms represent an interesting source of molecules for the design of novel pharmaceutical drugs.

Two antimicrobial peptides (AMPs), named La47 and Css54, were isolated from the venom of the spider Lachesana sp. and from the scorpion Centruroides suffusus suffusus, respectively. The primary structures of both La47 and Css54 were determined using N-terminal sequencing and mass spectrometry. La47 is identical to the AMP latarcin 3a obtained previously from the venom of the spider Lachesana tarabaevi, but the primary structure of Css54 is unique having 60% identities to the AMP ponericin-W2 from the venom of the ant Pachycondyla goeldii. Both La47 and Css54 have typical α-helix secondary structures in hydrophobic mimicking environments. The biological activities of both La47 and Css54 were compared with the AMP Pin2 isolated from the venom of the scorpion Pandinus imperator. La47 has lower antimicrobial and hemolytic activities compared with Css54 and Pin2. In addition, La47 and Pin2 were evaluated in the presence of the commercial antibiotics, chloramphenicol, ampicillin, novobiocin, streptomycin and kanamycin. Interestingly, the best antimicrobial combinations were obtained with mixtures of La47 and Pin2 with the antibiotics chloramphenicol, streptomycin and kanamycin, respectively. Furthermore, the novel peptide Css54 was evaluated in the presence of antibiotics used for the treatment of tuberculosis, isoniazid, rifampicin, pyrazinamide and ethambutol. Although the mixtures of Css54 with isoniazid, pyrazinamide or ethambutol inhibit the growth of Staphylococcus aureus, the best effect was found with rifampicin. Overall, these data show a motivating outlook for potential clinical treatments of bacterial infections using AMPs and commercial antibiotics.