The colony structure and reproductive biology of the afrotropical Mashona mole-rat, Cryptomys darlingi

Cryptomys darlingi occurs in the mesic Miombo woodland of north-eastem Zimbabwe. It occurs in colonies of up to nine individuals, in which reproduction is limited to one of the largest males and the largest female in the colony.
Reproduction and details of colony size and number of breeding animals in a colony are described for five complete field-captured colonies.
In captivity, mating is not confined to a particular season, and up to three litters of pups are orn per annum. The reproductive female initiates the pre-copulatory behaviour. The gestation lengti is 56–61 days ( n = 2 ). The new-born pups are altricial and litter size is small = 1.7 ± 0.5 ( n = 6). In this case, the pups first left the nest 10 days after birth, began to eat solids when 14 days old, and were fully weaned at five weeks. They began to spar with each other when 36–40 days old, but did not disperse and were incorporated into the colony. This suggests that the Mashona mole-rat colonies are composed of a founding pair and at least three successive litters of pups.     

Geographic differences in Blainville's beaked whale (Mesoplodon densirostris) echolocation clicks

Aim

Understanding cetacean species' distributions and population structure over space and time is necessary for effective conservation and management. Geographic differences in acoustic signals may provide a line of evidence for population-level discrimination in some cetacean species. We use acoustic recordings collected over broad spatial and temporal scales to investigate whether global variability in echolocation click peak frequency could elucidate population structure in Blainville's beaked whale (Mesoplodon densirostris), a cryptic species well-studied acoustically.

Location

North Pacific, Western North Atlantic and Gulf of Mexico.

Time period

2004–2021.

Major taxa studied

Blainville's beaked whale.

Methods

Passive acoustic data were collected at 76 sites and 150 cumulative years of data were analysed to extract beaked whale echolocation clicks. Using an automated detector and subsequent weighted network clustering on spectral content and interclick interval of clicks, we determined the properties of a primary cluster of clicks with similar characteristics per site. These were compared within regions and across ocean basins and evaluated for suitability as population-level indicators.

Results

Spectral averages obtained from primary clusters of echolocation clicks identified at each site were similar in overall shape but varied in peak frequency by up to 8 kHz. We identified a latitudinal cline, with higher peak frequencies occurring in lower latitudes.

Main conclusions

It may be possible to acoustically delineate populations of Blainville's beaked whales. The documented negative correlation between signal peak frequency and latitude could relate to body size. Body size has been shown to influence signal frequency, with lower frequencies produced by larger animals, which are subsequently more common in higher latitudes for some species, although data are lacking to adequately investigate this for beaked whales. Prey size and depth may shape frequency content of echolocation signals, and larger prey items may occur in higher latitudes, resulting in lower signal frequencies of their predators.     

Production of Verrucarol

Verrucarol was obtained from a simple procedure that involved the hydrolysis of a crude extract of a culture of Myrothecium verrucaria ATCC 24571.     

Differentiation of lactic streptococcal phages into phage species by DNA-DNA homology.

Twenty-five lactic streptococcal bacteriophages were differentiated by DNA homology into four species. Complete correlation was found between DNA homology groups and morphological characteristics of the phages except that two phage types, which differed in only the presence or absence of a collar, were one species by DNA homology. These findings were supported by serological data and differences in DNA molecular weights of the proposed species. The complete lack of homology between these phage species indicates that they are unlikely to have a recent common phage ancestor and that one morphological type of phage has not been derived by mutation from a phage of another morphological type.     

Serological studies of a host range mutant of a lactic streptococcal bacteriophage.

A host range mutant was isolated from a bacteriophage that attacked Streptococcus cremoris 114. The mutant was able to adsorb and grow on S. cremoris 266, where the parent phage could not. The mutant phage was unable to adsorb to the original bacterial host, S. cremoris 114. The change in host range was accompanied by an alteration in the neutralization antigen as shown by a change in neutralization rate by an anti-phage serum. Serum-blocking experiments confirmed the difference in neutralization antigen between parent and mutant phages. The two phages nevertheless had similar complement fixation antigens, confirming that one was a mutant derived from the other. A distinction between complement fixation and neutralization antigens, similar to that found for the coliphages and staphylococcal phages, has therefore been demonstrated for two lactic streptococcal phages.     

Purification and properties of phosphatidylglycerophosphate synthetase from mammalian liver mitochondria

The enzyme which catalyzes the synthesis of phosphatidylgly cerophosphate from an-glycerol-3-phosphated and cytidine diphosphate diacylglycerol was released from rat or pig liver mitochondrial membranes by extraction with Triton X-100 or Nonidet P-40. The detergent-extracted enzyme, like the activity of intact mitochondria, did not require added cations or lipids. The Triton extracts were fractionated by column chromatography on Bio-Gel A-1.5. The fractions obtained from the columns exhibited little activity in the standard assay system unless divalent cations were included. Additional stimulation (about twofold) was observed in the presence of added phospholipids. The cation requirement of the purified enzyme was relatively nonspecific with Mg2+, Ba2+, or Ca2+ providing maximal activity in the 10mM range. Either Mn2+ or Co2+ were stimulatory at somewhat lower concentrations but higher concentrations were inhibitory. Other cations such as Cd2+, Zn2+,Hg2+, or Cu2+ were ineffective as cofactors, and in the presence of Mg2+ inhibited the reaction at concentrations greater than 0.5 mM. The phospholipik stimulation was obtained specifically with phosphatidylethanolamines from natural or synthetic sources. Other diacylglycerophosphatides or lysophosphatides including lysophosphatidylethanolamine were ineffective.