Photoaffinity labelling of gizzard myosin with 3'-O-(4-benzoyl)-benzoic-adenosine 5'-triphosphate

The reaction of a photoaffinity analog, 3'-O-(4-benzoyl)-benzoic-adenosine 5'-triphosphate (BZ2ATP) with gizzard myosin is described. The incorporation of BZ2ATP into myosin is both specific and stoichiometric. About 2.2 mol BZ2ATP are incorporated/mol myosin resulting in the significant loss of EDTA(K+) ATPase activity. The Mg2+ and actin-activated ATPase activities are slightly inhibited. Addition of ATP (millimolar) during the photolysis reaction significantly inhibits incorporation of BZ2ATP into myosin. Our data show that the label is mainly incorporated into the heavy chain of myosin with some label in the 20-kDa light chain. Limited proteolysis of radioactively labeled myosin subfragment 1 with trypsin reveals the presence of radioactivity mainly in the 50-kDa fragment and some in the 29-kDa and 25-kDa fragments. However, our data on the ATP-sensitive incorporation of BZ2ATP into the tryptic fragments suggest that the 50-kDa peptide, not the 29-kDa peptide, may be located at or around the active site.     

Physiology, thermoregulation and bipedalism

It has long been recognized that the bipedal posture reduces the surface area of the body exposed to the sun. In recent years, a theory has been developed by Wheeler that bipedalism evolved in the ancestor of the Hominidae in order to help relieve thermal stress on the animals in open equatorial environments. Bipedalism was said to afford a distinct adaptive advantage over quadrupedalism by permitting hominids to remain active in the open throughout the day. The heat load of the hypothetical hominid comprises the external environment as modelled by Wheeler and the animal's internal environment (i.e., the internal heat generated by its metabolic and locomotor activities, and its evaporative and respirative cooling capacities). When these factors are integrated in the calculation of the animal's thermal budget, the putative advantage of the bipedal over the quadrupedal posture is considerably reduced. The simulations conducted in this study suggest that the increased time afforded to early hominids in the open by bipedalism was relatively short and, therefore, of little or no adaptive significance. These results suggest that thermoregulatory considerations cannot be implicated as a first cause in the evolution of bipedalism in the hominid ancestor.     

Adoptive immunotherapy with peripheral blood lymphocytes cocultured in vitro with autologous tumor cells and interleukin-2

A clinical trial of adoptive immunotherapy was carried out with peripheral blood lymphocytes (PBL), cocultured in vitro with autologous tumor cells and interieukin-2 (IL-2), in 14 patients with advanced melanoma. PBL from these patients were cocultured with irradiated autologous tumor cells for 7 days, which was followed by expansion in IL-2-containing medium. These lymphocytes were returned to the patient along with intravenous IL-2 at doses up to 2×10⁶ IU m^–2 day^–1. A dose of 300 mg/m² cyclophosphamide was administered to each patient intravenously 4 days prior to each treatment. Following coculture, the lymphocytes were primarily CD3⁺ T cells and they expressed varied degrees of cytotoxicity against autologous melanoma cells. In 9 patients the activated cells were al least 80% CD4⁺ and in 2 cases they were mostly CD8+. Some of the activated cells exhibited suppressor or helper activity in a functional regulatory coculture assay. No major therapeutic response was observed in this study. Minor responses were observed in 2 patients. Toxicities were those expected from the IL-2 dose administered.This work has been supported by an American Cancer Society Institutional Research Grant (ACS-IRG 91-230), by the University of Connecticut Clinical Research Center (grant 0021), and by the Hartford Hospital Research Fund (grant 1017-20-018). Dr. Sporn is a recipient of American Cancer Society Clinical Oncology Career Development Award 90-230     

Adsorptive pinocytosis of polycationic copolymers of vinylpyrrolidone with vinylamine by rat yolk sac and rat peritoneal macrophage

Polycationic copolymers of vinylpyrrolidone and vinylamine (10:0.77) were prepared, and ¹²⁵I-labelled with either Bolton-Hunter reagent or methyl 3,5-di-[¹²⁵I]iodohydroxybenzimidate. The rate of pinocytic capture of the copolymer was compared with that of ¹²⁵I-labelled polyvinylpyrrolidone, using rat visceral yolk sacs and rat macrophages cultured in vitro as test systems. Whereas polyvinylpyrrolidone was captured entirely by non-adsorptive pinocytosis, the cationic derivative was captured more efficiently, probably because it adsorbs to the cell surface. Copolymer of M_r 120 000 was internalized by macrophages somewhat more rapidly than copolymer of M_r 46 000, but was excluded from the yolk sac.     

Disorders of the Menstrual Cycle in Elite Female Ice Hockey Players and Figure Skaters

The purpose of this study was to assess and compare the incidence of delayed menarche and menstrual dysfunction among elite ice hockey players and figure skaters. Forty-three ice hockey players (23.5 ± 4.8 years, 68.2 ± 1.2 kg, 1.68 ± 0.01 m) and 39 figure skaters (17.5 ± 3.4 years, 53.7 ± 5.8 kg, 1.64 ± 0.05 m) completed a self-administered questionnaire on their menstrual status and history, training regimens and lifestyle. Age at menarche did not differ significantly between ice hockey players (13.3 ± 1.3 years) and figure skaters (13.7 ± 1.4 years). Menarche was unrelated to nationality, vigorous training premenarche or age at which the athlete began her sport, but was correlated with the age at menarche of the athletes’ mothers (r = 0.39, p < 0.05). Hormonal contraceptives were used by 35% of ice hockey players and 15% of the figure skaters. Amenorrhea and oligomenorrhea were experienced by 7.1% and 38.7% of postmenarcheal, ice hockey players and figure skaters respectively not using hormonal contraceptives. Menstrual dysfunction was associated with both age and age at menarche in the ice hockey players only. Training factors, and psychological pressure were perceived by the athletes to contribute to menstrual dysfunction. A greater training volume, younger age at commencing sport, lower body mass, greater subjective body image pressure and younger biological and gynaecological age were reported among the figure skaters, and were proposed to explain the higher incidence of menstrual dysfunction among the figure skaters compared with the ice hockey players. Figure skaters appear at increased risk of amenorrhea and oligomenorrhea compared with ice hockey players, which may be linked to training and physical characteristics of the sports.     

Primary structure of the nucleotide binding domain of the Ca,Mg-ATPase from cardiac sarcoplasmic reticulum

The nucleotide binding domain of the active site of the Ca,Mg-ATPase of cardiac sarcoplasmic reticulum (SR) has been isolated using fluorescein isothiocyanate (FITC) as an active site label and sequenced. After removal of non-specifically incorporated FITC with hydroxylamine, the amount of label incorporated was stoichiometric with residual ATPase activity, demonstrating that the label was incorporated uniquely at the active site. The SR was succinylated before digestion by trypsin in order to obtain a peptide of sufficient length to determine if the cardiac SR ATPase is a candidate for the unidentified cDNA clone recently sequenced by MacLennan et al. (Nature 316: 696-700, 1985). The sequence of the labeled SR peptide, obtained by affinity chromatography on a FITC antibody column, was T S M S K M F K G P E V I D R. This sequence was identical with that predicted by the unidentified clone and is significantly different from the sequence reported by Kirley et al. (Biochem. Biophys. Res. Commun. 130: 732-738, 1985) for a FITC labeled peptide isolated from cardiac SR.     

Population modelling and genetics of a critically endangered Madagascan palm Tahina spectabilis

Madagascar is home to 208 indigenous palm species, almost all of them endemic and >80% of which are endangered. We undertook complete population census and sampling for genetic analysis of a relatively recently discovered giant fan palm, the Critically Endangered Tahina spectablis in 2008 and 2016. Our 2016 study included newly discovered populations and added to our genetic study. We incorporated these new populations into species distribution niche model (SDM) and projected these onto maps of the region. We developed population matrix models based on observed demographic data to model population change and predict the species vulnerability to extinction by undertaking population viability analysis (PVA). We investigated the potential conservation value of reintroduced planted populations within the species potential suitable habitat. We found that the population studied in 2008 had grown in size due to seedling regeneration but had declined in the number of reproductively mature plants, and we were able to estimate that the species reproduces and dies after approximately 70 years. Our models suggest that if the habitat where it resides continues to be protected the species is unlikely to go extinct due to inherent population decline and that it will likely experience significant population growth after approximately 80 years due to the reproductive and life cycle attributes of the species. The newly discovered populations contain more genetic diversity than the first discovered southern population which is genetically depauperate. The species appears to demonstrate a pattern of dispersal leading to isolated founder plants which may eventually lead to population development depending on local establishment opportunities. The conservation efforts currently put in place including the reintroduction of plants within the species potential suitable habitat if maintained are thought likely to enable the species to sustain itself but it remains vulnerable to anthropogenic impacts.     

Correction to: Microhabitats of sharknose goby (Elacatinus evelynae) cleaning stations and their links with cleaning behaviour

Coral Reefs - A correction to this paper has been published: https://doi.org/10.1007/s00338-021-02111-z     

Endemic infection reduces transmission potential of an epidemic parasite during co-infection

Endemic, low-virulence parasitic infections are common in nature. Such infections may deplete host resources, which in turn could affect the reproduction of other parasites during co-infection. We aimed to determine whether the reproduction, and therefore transmission potential, of an epidemic parasite was limited by energy costs imposed on the host by an endemic infection. Total lipids, triacylglycerols (TAG) and polar lipids were measured in cockroaches (Blattella germanica) that were fed ad libitum, starved or infected with an endemic parasite, Gregarina blattarum. Reproductive output of an epidemic parasite, Steinernema carpocapsae, was then assessed by counting the number of infective stages emerging from these three host groups. We found both starvation and gregarine infection reduced cockroach lipids, mainly through depletion of TAG. Further, both starvation and G. blattarum infection resulted in reduced emergence of nematode transmission stages. This is, to our knowledge, the first study to demonstrate directly that host resource depletion caused by endemic infection could affect epidemic disease transmission. In view of the ubiquity of endemic infections in nature, future studies of epidemic transmission should take greater account of endemic co-infections.     

Nitric oxide and prostacyclin-dependent pathways involvement on in vitro induced hypothermia

Nitric oxide and prostacyclin are endogenous endothelium-derived vasodilators, but little information is available on their release during hypothermia. This study was carried out to test the hypothesis that endothelium may modulate vascular reactivity to decreased temperature changes. Segments of contracted (prostaglandin F(2alpha), 2x10(-6)M) canine coronary, femoral, and renal arteries, with and without endothelium, were in vitro ("organ chambers") exposed to progressive hypothermia (from 37 to 10 degrees C) in graded steps. The study is limited to physiological measurements of vascular tone, in the presence or absence of PGI(2) and/or NOS inhibitors, which show correlation with the relaxation. Hypothermia induced vasodilatation of vessels with intact endothelium, which became endothelium-independent below 20 degrees C. This vasodilatation began at 35 degrees C and, in the presence of indomethacin (2x10(-6)M), at 30 degrees C. Endothelium-dependent vasodilatation to hypothermia was blocked by L-NMMA or L-NOARG (10(-5)M), two competitive inhibitors of nitric oxide synthase (n=5 each, P<0.05). Oxyhemoglobin (2x10(-6)M) also inhibited vasodilatation induced by hypothermia (n=6, P<0.05). Pretreatment with either atropine or pirenzepine (10(-6)M) inhibited hypothermia-mediated vasodilatation (n=5 each, P<0.05). The present in vitro study concluded that the endothelium is sensitive to temperature variations and indicated that PGI(2) and NO-dependent pathways may be involved endothelium-dependent relaxation to hypothermia. The endothelium-dependent vasodilatation to hypothermia, in systemic and coronary arteries, is mediated by the M1 muscarinic receptor.