Sex steroids and epidermal glands in two species of gekkonine lizards.

In vivo and in vitro experiments on the endocrine relationships of epidermal glands in the tokay Gekko gecko, and the common house gecko Hemidactylus bowringii are reported. The results show that certain aspects of beta-gland differentiation involve a synergistic action between androgens and those hormones responsible for controlling the normal shedding cycle, while other aspects are solely under androgenic control. Pre-anal organ activity appears to be solely under androgenic control.     

Biological spectrum of two spirolactone derivatives with some observations on anti-fertility activity.

Bioassays were conducted to determine various endocrinological properties of two spirolactone derivatives, 4',5'-dihydrospiro-[estr-4-ene-17,2'(3'H)-furan]-3-one (Compound I) and dispiro[cyclopropane-1,6'-estr-4'-ene-17',2"(3"h)-furan]-3'-one (Compound II). They proved to be very potent estrogen antagonists in immature mice and castrate ewes and neither exhibited inherent estrogenicity. They were moderately active as progestins and gonadotropin inhibitors. Compound II possessed slight androgenic activity and was more active orally than I. Compound I underwent a limited amount of testing in normally cycling rhesus monkeys. It was found to increase viscosity of the cervical mucus and, in oral doses of 0.5 or 2.0 mg/day, prevented pregnancy. One animal given 0.5 mg/day did become pregnant in her first treatment cycle, probably before a drug effect had been established. The results obtained indicate both compounds have potential utility as low-dose oral contraceptives.     

Epidermal glands in cordylid lizards,with special reference to generation glands

We investigated inter‐ and intraspecific variation in epidermal gland characteristics in cordylid lizards. Our particular interest was whether a causal relationship exists between the presence of generation glands and lifestyle, i.e. in rock‐dwelling or ground‐dwelling lizards. We established that both femoral and generation glands are always present in adult males, but that species can be divided into three categories on the basis of the presence of these glands in adult females: both femoral and generation glands absent; femoral glands present, but generation glands absent; and both femoral and generation glands present. The absence of epidermal glands in females appears to be the basal condition in the Cordylidae. All cordylid species are sexually dimorphic as far as generation gland number is concerned, with females having consistently less glands than males. Gland number in females is strongly affected by climate, being lower in cooler compared with warmer environments. In males, there is no clear geographical pattern, although in some clades males of high‐altitude species have more generation glands than males of species occurring at lower altitudes. At least four of the five ground‐dwelling species in the family display unique generation gland characteristics, compared with rock‐dwelling species, reflecting the continued importance of generation glands in terrestrial environments. © 2009 The Linnean Society of London, Zoological Journal of the Linnean Society, 2010, 158 , 312–324.     

Seasonal activity and energetics of two species of varanid lizards in tropical Australia

The field metabolic rates (FMR) and rates of water flux were measured in two species of varanid lizards over five periods of the year in tropical Australia. The energetics of these species were further investigated by directly measuring activity (locomotion) and body temperatures of free-ranging animals by radiotelemetry, and by measuring standard metabolic rate (over a range of body temperatures) and activity metabolism in the laboratory. Seasonal differences in the activity and energetics were found in these goannas despite similar, high daytime temperatures throughout the year in tropical Australia. Periods of inactivity were associated with the dry times of the year, but the onset of this period of inactivity differed with respect to habitat even within the same species. Varanus gouldii, which inhabit woodlands only, were inactive during the dry and late dry seasons. V. panoptes that live in the woodland had a similar seasonal pattern of activity, but V. panoptes living near the floodplain of the South Alligator River had their highest levels of activity during the dry season when they walked long distances to forage at the receding edge of the floodplain. However, during the late dry season, after the floodplain had dried completely, they too became inactive. For V. gouldii, the rates of energy expenditure were 196 kJ kg^–1 day^–1 for active animals and 66 kJ kg^–1 day^–1 for inactive animals. The rates of water influx for these groups were respectively 50.7 and 19.5 ml kg^–1 day^–1. For V. panoptes, the rates of energy expenditure were 143 kJ kg^–1 day^–1 for active animals and 56 kJ kg^–1 day^–1 for inactive animals. The rates of water influx for these two groups were respectively 41.4 and 21.0 ml kg^–1 day^–1. We divided the daily energy expenditure into the proportion of energy that lizards used when in burrows, out of burrows but inactive, and in locomotion for the two species during the different seasons. The time spent in locomotion by V. panoptes during the dry season is extremely high for a reptile (mean of 3.5 h/day spent walking), and these results provide an ecological correlate to the high aerobic capacity found in laboratory measurements of some species of varanids.     

The post-natal development of holocrine epidermal specializations in gekkonid lizards.

The abdominal escutcheon, and certain aspects of pre-anal organ morphology, have been studied in Sphaerodactylus spp. and Gekko vittatus respectively. These epidermal modifications are male characteristics. The sphaerodactyline escutcheon becomes larger by the peripheral addition of specialized scales with increasing size of the individuals: this relationship is much more clearcut in S. cinereus than in the notatus species group (sensu Shreves, '68), and the possible reasons for this are discussed. The number of pre-anal organs varies between populations of G. vittatus, but within populations remains constant throughout life. Individual organs increase steadily in size throughout life. These data are discussed with reference to current interpretations of gekkonid gland evolution, and of factors controlling epidermal cell proliferation and differentiation.     

Immunoelectron microscopic localization of epidermal growth factor in the eccrine and apocrine sweat glands.

We studied the localization of the epidermal growth factor (EGF) in eccrine and apocrine sweat glands with light microscopic and electron microscopic immunohistochemistry. Anti-human EGF (anti-hEGF) polyclonal antiserum and anti-hEGF monoclonal antibody (MAb) were used for the study. Light microscopic immunohistochemistry with monoclonal and polyclonal antibodies showed that hEGF-like immunoreactivity was strongly positive in the myoepithelial cells and weakly positive in the secretory cells of eccrine sweat glands. In apocrine sweat glands, it was strongly positive in the secretory cells as well as in the myoepithelial cells. Immunoelectron microscopy with polyclonal antibody showed that hEGF-like immunoreactivity was present in secretory granules of apocrine secretory cells. These granules had mitochondrion-like internal structure. No reactivity was observed on the eccrine secretory cells by immunoelectron microscopy. Neither dark cell granules nor mitochondria in eccrine secretory cells were labeled with anti-hEGF antibody. In both eccrine and apocrine sweat glands, hEGF-like immunoreactivity was diffusely present in the cytoplasm of myoepithelial cells. However, nuclei and mitochondria of myoepithelial cells were devoid of immunoreactivity for hEGF. Our observations indicate that apocrine sweat glands may secrete more hEGF in the sweat than eccrine sweat glands.     

Induction of epidermal growth factor by tri-iodo-L-thyronine in the submandibular glands of mice with testicular feminization

The content of epidermal growth factor (EGF) as a high molecular weight complex (HMW-EGF) in the submandibular glands of mice was measured simply by a single radial immunodiffusion method. In female mice, the amount of HMW-EGF was increased 10-fold by tri-iodo-L-thyronine (T3) and 60-fold by 5 alpha-dihydrotestosterone (5 alpha-DHT). In mice with testicular feminization (Tfm), which are genetically deficient in androgen receptor, T3 but not 5 alpha-DHT increased the HMW-EGF from a non-detectable level to 5.4 +/- 0.94 micrograms/mg protein. It was concluded that EGF is also synthesized under the control of thyroid hormone in vivo, and that androgen was not involved in this induction of EGF by thyroid hormone.     

Light- and electron microscopic observations on parathyroid glands in different age groups of rats

The parathyroid hormone (PTH) acts on bones, intestines, and kidneys to maintain the calcium homeostasis which, in turn, is a main factor in controling the parathyroid (PT) gland activity. In all mammals studied, the chief cells of PT glands changed their size, shape, and cytoplasmic structure due to different functional states which vary the serum calcium levels. The chief cells of the rat PT glands were classified as dark and light. The dark cells may constitute an active form, characterized mainly by the abundant free ribosomes, conspicuous rough endoplasmic reticulum, and GOLGI complexes, greater number of secretory granules (SG) and increased tortuosity of the plasma membranes as compared to the light ones which were considered as a less active type of cells. Due to different calcium requirements in newborn and young rats for the ossification of growing skeleton and in adult and senile rats with consolidate mature bones, the PT glands studied with electron microscope showed various cytological features. The parenchyma of newborn and young PT glands was composed by dark chief cells. The light chief cells were more frequent in adult and senile animals as a less active type of cell. Mature SG were only occasionally observed in dark cells of newborn, young and adult PT glands. They may constitute a reserve supply of PTH but probably not the main way of secretion, according to their little number. Another pool of PTH probably answers the needs for the small basal variations in the steady-state secretion and may be represented by the vesicles observed in the chief cells cytoplasm.     

Competition and character displacement in two species of scincid lizards

The role of competition in habitat occupation and character displacement is investigated in two species of alpine lizards (Niveoscincus microlepidotus and N. greeni), using both controlled competition experiments and field‐based ecological work. Competition experiments demonstrate that interspecific aggression occurs between these closely related species, with the larger and more aggressive N. greeni being socially dominant. When these species occur in sympatry, N. microlepidotus was found to shift its habitat occupation to the heathlands, which provide less thermal opportunities. In addition, a reduction in body size occurred in both adult and neonatal N. microlepidotus at sympatric field sites. Differences in body size between N. microlepidotus and N. greeni in sympatry were significantly greater than in allopatry, indicating that character displacement is occurring. Results, combined with previous molecular and biogeographical data, suggest that there is a trend towards a reduction in body size and a restriction in habitat occupation in N. microlepidotus in the north‐east periphery of its distribution, which is shaped by competition with N. greeni.     

Taxonomic observations on some species of the genusParietaria

Taxonomy and distribution ofParietaria serbica.Pan?,P. lusitanica L.,P. micrantha Lebed. andP. mauritanica Dur. is briefly discussed.P. serbica is an endemic species of SE. Europe and is related toP. judaica Strand in L.P. lusitanica is divided into two subspecies.P. micrantha is treated as a variety ofP. lustitanica subsp.chersonensis (Lang) Chratek.P. mauritanica is reported as a new species for Sicily.     

Microtubules in some unicellular glands of two leeches

Summary What appear to be two types of unicellular glands are found in the integument of the leech, Helobdella stagnalis. Type I cells are characterized by a peripheral, subplasmalemmal sack of rough endoplasmic reticulum and accumulations of secretory product in the form of small membrane bound droplets. Type II cells are characterized by large numbers of closely opposed sacks of rough endoplasmic reticulum and secretory product in the form of large, evidently amorphous accumulations of secretory product.Both cell types attenuate into long, slender processes through which the secretory product passes to the surface of the leech. Each process is characterized by a subplasmalemmal sack of ER which runs the entire length of the process and is continuous, at the proximal end of the process, with sacks of rough ER. Associated with the inner member of the ER membrane pair are microtubules with a diameter of approximately 240 Å.A similar arrangement of a subplasmalemmal ER sack associated with microtubules also is found in secretory processes of the leech, Macrobdella decora.The possible source and functions of these microtubules are discussed.This investigation was supported by Public Health Service grant number GM 723-04 of the National Institutes of Health.The author is greatly indebted to Dr. David B. Slautterback for his advice and encouragement during the course of this investigation.