Size Effects on Mating and Egg Production in the Miami Blue Butterfly

Body size is often related to reproductive success in insects, but the direction and strength of this relationship differs greatly among systems. We studied the effects of adult size on probability of mating and egg production in the Miami blue butterfly. We found that likelihood of mating was invariant with respect to size. Larger females lived longer, and both size and lifespan positively influenced egg production. However, neither the number of copulations nor the size of male mates had any effect on female fecundity. We discuss these results in the context of butterfly mating systems, larval growth strategies and the possible effects of captive conditions on reproductive behavior.     

Plasmodium falciparum gametocyte formation in vitro: its stimulation by phorbol diesters and by 8-bromo cyclic adenosine monophosphate

Phorbol 12-myristate 13-acetate increased the number of gametocytes by 50 to 100% in well or petri dish cultures of the HB-3 clone of Plasmodium falciparum. Phorbol dibutyrate had a similar effect. The optimal concentration for each of these agents was 20 ng/ml or approximately 30 nM. No effect of forskolin was found, other than a general inhibition of growth at concentrations over 10 microM. An inhibitor of phosphodiesterase, 8-bromo cyclic adenosine monophosphate (at concentrations of 0.1 and 1.0 microM) also significantly increased the number of gametocytes formed by this clone.     

A Clinical Trial to Evaluate the Efficacy of α-Viniferin in Staphylococcus aureus – Specific Decolonization without Depleting the Normal Microbiota of Nares

Staphylococcus aureus is currently a significant multidrug-resistant bacterium, causing severe healthcare-associated and community-acquired infections worldwide. The current antibiotic regimen against this pathogen is becoming ineffective due to resistance, in addition, they disrupt the normal microbiota. It highlights the urgent need for a pathogen-specific drug with high antibacterial efficacy against S. aureus. α-Viniferin, a bioactive phytochemical compound, has been reported to have excellent anti-Staphylococcus efficacy as a topical agent. However, so far, there were no clinical trials that have been conducted to elucidate its efficacy. The present study aimed to investigate the antibacterial efficacy of α-viniferin against S. aureus in a ten-day clinical trial. Based on the results, α-viniferin showed 50% minimum inhibitory concentrations (MIC₅₀ values) of 7.8 μg/ml in culture broth medium. α-Viniferin was administered in the nares three times a day for ten days using a sterile cotton swab stick. Nasal swab specimens were collected before (0 days) and after finishing the trial (10^th day), and then analyzed. In the culture and RT-PCR-based analysis, S. ureus was reduced significantly: 0.01. In addition, 16S ribosomal RNA-based amplicon sequencing analysis showed that S. aureus reduced from 51.03% to 23.99% at the genus level. RNA-seq analysis was also done to gain insights into molecular mechanisms of α-viniferin against S. aureus, which revealed that some gene groups were reduced in 5-fold FC cutoff at two times MIC conditions. The study results demonstrate α-viniferin as a potential S. aureus-specific drug candidate.     

Pathogenicity of clinical Salmonella enterica serovar Typhimurium isolates from Thailand in a mouse colitis model

Salmonella enterica serovar Typhimurium (S. Typhimurium [STM]) is a leading cause of nontyphoidal salmonellosis (NTS) worldwide. The pathogenesis of NTS has been studied extensively using a streptomycin-pretreated mouse colitis model with the limited numbers of laboratory STM strains. However, the pathogenicity of the clinically isolated STM (STMC) strains endemic in Thailand in mice has not been explored. The aim of this study was to compare the pathogenicity of STMC strains collected from Northern Thailand with the laboratory STM (IR715) in mice. Five STMC isolates were obtained from the stool cultures of patients with acute NTS admitted to Maharaj Nakorn Chiang Mai Hospital in 2016 and 2017. Detection of virulence genes and sequence type (ST) of the strains was performed. Female C57BL/6 mice were pretreated with streptomycin sulfate 1 day prior to oral infection with STM. On Day 4 postinfection, mice were euthanized, and tissues were collected to analyze the bacterial numbers, tissue inflammation, and cecal histopathological score. We found that all five STMC strains are ST34 and conferred the same or reduced pathogenicity compared with that of IR715 in mice. A strain-specific effect of ST34 on mouse gut colonization was also observed. Thailand STM ST34 exhibited a significant attenuated systemic infection in mice possibly due to the lack of spvABC-containing virulence plasmid.     

Comparative infectivity of knobless and knobby clones of Plasmodium falciparum in splenectomized and intact Aotus trivirgatus monkeys

In two experiments, two knobless (K-) and two knob-producing (K+) clone-cultures of Plasmodium falciparum, FCR-3/Gambia strain, were injected into four Aotus trivirgatus monkeys. The parasitemia in the K(-)-infected splenectomized (S-) monkey rose to a peak of 2.1% on the 16th day, while it reached only 0.7% at the same time in the K+ infected S- animal. Passage from these animals (karyotype VI) into two intact (S+), naive monkeys of karyotype III resulted in very light infections somewhat higher with K+ than with K-. This experiment was repeated with two different clones in two other S- monkeys of karyotype III. Again, the parasitemia of the K+ infected monkey was appreciably below that of the K- monkey. Transfer of parasites into S+ animals of karyotype II resulted in very light infection and, as before, the K+ did somewhat better. About 2 months after its initial infection, the K(+)-infected S- animal from the second experiment came down with a recurrent malaria infection. Electron-microscopic observations on blood from this monkey revealed that the previously K+ parasites had become knobless (K-). Transfer of this material into an S+, naive monkey, again, gave a barely detectable infection. After splenectomy a recrudescence occurred. The results strongly indicate that K- clones of P. falciparum are more infectious to S- Aotus monkeys than K+ clones, whereas in S+ monkeys the situation is reversed.