Alternative base pairing between 5''- and 3''-terminal sequences of small subunit RNA may provide the basis of a conformational switch of the small ribosomal subunit.

The compiled sequences of small subunit ribosomal RNAs have been screened for base complementary between 5'- and 3'-terminal regions. Highly conserved complementary sequences are found which allow formation of a helix between the two ends of 5 or 6 base pairs. This helix is composed of sequences from the loop region of the first 5'-terminal stem and from sequences immediately distal to the last stem (the Me2A-stem) of the 3' terminus and therefore allows a coaxial stacking with either of these two flanking stems. Formation of the 5'/3'-helical arrangement is, however, only possible at the cost of dissolving the 'pseudo-knot' helix between the 5'-terminal region and the internal region of small subunit RNA. It is postulated that the mutually exclusive conformational states are in dynamic equilibrium and that they correlate with distinct functional states of the small ribosomal subunit. The 'pseudo-knot' containing conformation with the 3'-terminal sequences more exposed is likely to represent the initiating state, whereas the 5'/3' terminal paired 'closed' conformation may represent the elongating state in which interaction with fortuitous ribosomal binding sequences of mRNAs is avoided.     

Functional Characterization of a Novel Class of Morantel-Sensitive Acetylcholine Receptors in Nematodes

Acetylcholine receptors are pentameric ligand–gated channels involved in excitatory neuro-transmission in both vertebrates and invertebrates. In nematodes, they represent major targets for cholinergic agonist or antagonist anthelmintic drugs. Despite the large diversity of acetylcholine-receptor subunit genes present in nematodes, only a few receptor subtypes have been characterized so far. Interestingly, parasitic nematodes affecting human or animal health possess two closely related members of this gene family, acr-26 and acr-27 that are essentially absent in free-living or plant parasitic species. Using the pathogenic parasitic nematode of ruminants, Haemonchus contortus, as a model, we found that Hco-ACR-26 and Hco-ACR-27 are co-expressed in body muscle cells. We demonstrated that co-expression of Hco-ACR-26 and Hco-ACR-27 in Xenopus laevis oocytes led to the functional expression of an acetylcholine-receptor highly sensitive to the anthelmintics morantel and pyrantel. Importantly we also reported that ACR-26 and ACR-27, from the distantly related parasitic nematode of horses, Parascaris equorum, also formed a functional acetylcholine-receptor highly sensitive to these two drugs. In Caenorhabditis elegans, a free-living model nematode, we demonstrated that heterologous expression of the H. contortus and P. equorum receptors drastically increased its sensitivity to morantel and pyrantel, mirroring the pharmacological properties observed in Xenopus oocytes. Our results are the first to describe significant molecular determinants of a novel class of nematode body wall muscle AChR.     

Determinants of serum levels of surfactant proteins A and B and Clara cell protein CC16

Increased leakage of surfactant proteins A and B (SP-A and SP-B) and Clara cell secretory protein (CC16) from the air spaces into the circulation occurs in a range of respiratory conditions. However, circulating levels depend not only on the rate of entry into the circulation, but also on the rate of clearance. In order to clarify the role of the kidney in the clearance of these proteins, serum levels were related to markers of glomerular filtration in 54 non-smoking patients with varying degrees of renal dysfunction, none of whom had respiratory disease or were receiving dialysis at the time of sampling. Serum SP-A was related to SP-B (r=0.53, p<0.001) and to CC16 (r=0.33, p<0.02). Similarly, SP-B was related to CC16 (r=0.39, p<0.004). Stepwise multiple linear regression analysis suggested that serum SP-A and SP-B are influenced by age (～20 and ～25% of variance, respectively), whereas CC16 is determined by renal function and, to a lesser extent, by body weight (～63% of variance in total). We conclude that CC16 is cleared from blood by the renal route, whereas SP-A and SP-B are not. Serum SP-A and SP-B are influenced by age, which we speculate reflects increased damage to the alveolocapillary barrier.     

Syphilis Screening among 27,150 Pregnant Women in South Chinese Rural Areas Using Point-of-Care Tests

Objectives

To determine the prevalence and correlates of syphilis among pregnant women in rural areas of South China.

Methods

Point-of-care syphilis testing was provided at 71 health facilities in less developed, rural areas of Guangdong Province. Positive samples were confirmed at a local referral center by toluidine red unheated serum tests (TRUST) and Treponema pallidum particle agglutination (TPPA) tests.

Results

Altogether 27,150 pregnant women in rural Guangdong were screened for syphilis. 106 (0.39%) syphilis cases were diagnosed, of which 78 (73.6%) received treatment for syphilis. Multivariate analysis revealed that older pregnant women (31–35 years old, aOR 2.7, 95% CI 0.99–7.32; older than 35 years old, aOR 5.9, 95% CI 2.13–16.34) and those with a history of adverse pregnant outcomes (aOR 3.64, 95% CI 2.30–5.76) were more likely to be infected with syphilis.

Conclusions

A high prevalence of syphilis exists among pregnant women living in rural areas of South China. Enhanced integration of syphilis screening with other routine women''s health services (OB GYN, family planning) may be useful for controlling China''s syphilis epidemic.     

Habitat use of the ocelot (Leopardus pardalis) in Brazilian Amazon

Amazonia forest plays a major role in providing ecosystem services for human and sanctuaries for wildlife. However, ongoing deforestation and habitat fragmentation in the Brazilian Amazon has threatened both. The ocelot is an ecologically important mesopredator and a potential conservation ambassador species, yet there are no previous studies on its habitat preference and spatial patterns in this biome. From 2010 to 2017, twelve sites were surveyed, totaling 899 camera trap stations, the largest known dataset for this species. Using occupancy modeling incorporating spatial autocorrelation, we assessed habitat use for ocelot populations across the Brazilian Amazon. Our results revealed a positive sigmoidal correlation between remote‐sensing derived metrics of forest cover, disjunct core area density, elevation, distance to roads, distance to settlements and habitat use, and that habitat use by ocelots was negatively associated with slope and distance to river/lake. These findings shed light on the regional scale habitat use of ocelots and indicate important species–habitat relationships, thus providing valuable information for conservation management and land‐use planning.     

Blood monocytes: distinct subsets, how they relate to dendritic cells, and their possible roles in the regulation of T-cell responses

Monocytes can have important effects on the polarization and expansion of lymphocytes and may contribute to shaping primary and memory T-cell responses in humans and mice. However, their precise contribution in terms of cellular subsets and the molecular mechanisms involved remains to be determined. Mouse monocytes originate from a bone marrow progenitor, the macrophage and DC precursor (MDP), which also gives rise to conventional dendritic cells through a separate differentiation pathway. Mouse monocytes may be grouped in different functional subsets. The CD115(+) Gr1(+) 'inflammatory' monocyte subset can give rise not only to immunostimulatory 'TipDCs' in infected mice but also to immunosuppressive 'myeloid-derived suppressor cells' in tumor-bearing mice. CD115(+) Gr1(+) monocytes can also contribute to the renewal of several resident subsets of macrophages and DCs, such as microglia and Langerhans cells, in inflammatory conditions. The CD115(+) Gr1(-) 'resident' monocyte subset patrols blood vessels in the steady state and extravasates during infection with Listeria monocytogenes or in the healing myocardium. CD115(+) Gr1(-) monocytes are responsible for an early and transient inflammatory burst during Lm infection, which may play a role in the recruitment of other effector cells and subsequently differentiate toward 'M2'-like macrophages that may be involved in wound healing. More research will no doubt confirm the existence of more functional subsets, the developmental relationship between mouse subsets as well as the correspondence between mouse subsets and human subsets of monocytes. We will discuss here the potential roles of monocytes in the immune response, the existence of functional subsets and their relationship with other myeloid cells, including dendritic cells.     

Identification,characterization, and developmental profile of a high molecular weight,juvenile hormone-binding protein in the hemolymph of the migratory grasshopper,Melanoplus sanguinipes

In the hemolymph of Melanoplus sanguinipes, a high molecular weight juvenile hormone binding protein (JHBP) was identified by photoaffinity labelling and found to have a M_r of 480,000. The JHBP, purified using native gel electrophoresis followed by electroelution, has an equilibrium dissociation constant for JH III of 2.1 nM and preferentially binds JH III over JH I. Antibody raised against JHBP recognized only the 480,000 band. Under denaturing conditions the native JHBP gave a single band with a M_r 78,000. The antibody against native JHBP recognized only the 78,000 protein in SDS-treated hemolymph samples, indicating that JHBP is a hexamer in this species. The concentration of JHBP fluctuates in both the sexes during nymphal and adult development in parallel with total protein content of hemolymph. © 1995 Wiley-Liss, Inc.     

Identification of indolepyruvic acid as an intermediate of rebeccamycin biosynthesis

Summary Experimental evidence is presented to demonstrate that indolepyruvic acid is an intermediate in the rebeccamycin biosynthetic pathway. [3-¹⁴C]Indolepyruvic acid was prepared and efficiently incorporated (8%) into rebeccamycin bySaccharothrix aerocolonigenes.